Poaceae

Botanizing the Scour Trail at Johnson’s Shut-Ins State Park

/ Ted C. MacRae / Leave a comment

It’s been too long since I’ve been able to go out with the WGNSS Botany Group on their weekly Monday outing—a consequence of travel and renovations on top of the frenetic-as-usual insect-collecting season. The result is that my attendance on the Botany Group outings is semi-regular during fall/winter but spotty at best during spring/summer. That may seem exactly the opposite of what would be optimum for studying plants, but as a naturalist to the core I have no trouble finding things of interest no matter the season. Especially when the destination is a place as fascinatingly diverse as Johnson’s Shut-Ins State Park—best known previously for its rhyolite “shut-ins” but now mostly for the gashing scour zone that was ripped across it in Dec 2005 when a catastrophic failure of the reservoir atop nearby Proffit Mountain released one billion gallons of water that tore through the landscape in a matter of 12 minutes. The geology exposed by the scour and the living experiment of biological succession that began afterwards are both fascinating, making the Scour Trail one of the Missouri Ozarks’ most interesting day hikes.

17-year-old “scour zone” below Proffit Mountain Reservoir.

Our chief target for the day was Hamamelis virginiana (common or American witch-hazel), which blooms in November and December and is restricted in Missouri to a few counties in the St. Francois Mountains and the extreme southwestern corner of the state. Interestingly, there is a second species of witch hazel—H. vernalis (Ozark witch hazel), more common in Missouri but much more restricted globally—that occurs here, but as it blooms later in winter (January/February) we did not expect to see it on this trip. We found the former reliably, though not abundantly, and among the last plants we found in bloom were some with the freshest (and best-illuminated by the low-angled sun) flowers. At one point while we were still within the dry-mesic upland deciduous forest uphill from the scour zone, we saw a nice colony of the patch-forming Diarrhena obovata (beak grass). This is an attractive grass that does well in shade and should be utilized more as an ornamental.

Hamamelis virginiana (common or American witch-hazel).
Hamamelis virginiana (common or American witch-hazel).
Diarrhena obovata (beak grass) in dry-mesic upland deciduous forest.

The overlook provided a stunning overview of the scour zone from an elevated vantage—the since rebuilt Proffit Mountain Reservoir rising ominously above it as an almost deliberate reminder of its potential power—before the descent down into the scour zone. It’s an almost alien landscape with an irregular, unweathered floor of exposed bedrock strewn with rocks ranging from pebbles to boulders. Sycamore and willow are the early leaders in the now 17-year-old race to recolonize the barren swath of land, but lack of toeholds for roots to grow is a bigger problem for this future forest than lack of sunlight by taller neighbors. At one point, we spotted a large bush heavily laden with dense clusters of berries atop a pile of rocks. While the more astute botanists in the group recognized it for what it was, I was dumbfounded as to its identity until it was revealed to me to be none other than Toxicodendron radicans (poison ivy)—the largest, densest, most heavily berry-laden “bush” form of the species I have ever seen. So impressive it was that seven botanists gave it much more than just a trifling look.

“Bush” form of Toxicodendron radicans (eastern poison ivy).
Dense clusters of berries on “bush” form of Toxicodendron radicans (eastern poison ivy).

About halfway down the scour zone we encountered the “great unconformity”—previously hidden by topsoil and forest but now exposed. Here, knobs of 1.3 billion-year-old granite are surrounded by 540 million-year-old dolomite deposited atop the granite in the shallow Cambrian seas that once covered all but the tallest of these by then already ancient knobs—mere nubs of the towering mountains they once were but worn down nearly to sea level by nearly a billion years of relentless rain and wind. The exposures of pink granite, their large embedded crystals glistening sharply in the sunlight, contrasted starkly with the dark gray dolomite surround them, representing an incomprehensible gap of nearly 800 million years in the record of Earth’s history preserved in the rocks. The entire history of multicellular life on Earth could be swallowed by such a gap!

Unconformity with 1.3 billion-year-old Precambrian granite (pink rock) surrounded by 540 million-year-old Cambrian dolomite (gray rock) in scour zone below Profitt Mountain

As an entomologist, I cannot ever stop being on the lookout for insects, no matter what the season. Even though temps were well on the chilly side, I still managed to discern a couple of small wolf spiders, and somehow I managed to see a small ant cadaver on a twig that had succumbed to an insect-pathogenic fungus in the Ophiocordyceps unilateralis complex. Even the botanists around me started taking advantage of the opportunity for insect education. Len and Michael noticed a gall on a small Quercus muhlenbergii (chinquapin oak) which turned out to be the work of Disholcaspis quercusglobulus (round bullet gall wasp), and John noticed a colony of Prociphilus tessellatus (woolly alder aphid) on Alnus glutinosa (European alder). Closer inspection revealed an adult Harmonia axyridis (Asian lady beetle) preying upon the aphids.

Small wolf spider (family Lycosidae) on moss-covered rock in dry-mesic upland deciduous forest.
Pardosa sp. (thin-legged wolf spider) on exposed granite in 17-year old scour zone through dry-mesic upland deciduous forest.
Ophiocordyceps unilateralis complex insect-pathogenic fungus infecting ant (family Formicidae) in dry-mesic, deciduous, upland forest.
Disholcaspis quercusglobulus (round bullet gall wasp) on Quercus muhlenbergii (chinquapin oak) in dry deciduous upland forest.
Harmonia axyridis (Asian lady beetle) preying upon Prociphilus tessellatus (woolly alder aphid) on Alnus glutinosa (European alder)

It was as enjoyable an outing as I’d hoped (how can four hours in the woods be anything BUT enjoyable), and I hope not to let so much time pass before the next time I’m able to join the group!

©️ Ted C. MacRae 2022

A sand prairie autumn

/ Ted C. MacRae / 12 Comments

Splitbeard bluestem seed headsAsk any astronomer when autumn begins, and they will likely tell you it begins at the autumnal equinox – when shortening days and lengthening nights become equal as the sun crosses over the celestial equator. According to them, fall began this year on September 22 – at 11:44:18 A.M. EDT, to be precise. I agree that autumn begins at a precise moment, but it is not at the equinox. Rather, it is that unpredictable moment when a sudden crispness in the air is felt, when the sky somehow seems bluer and shadows seem sharper, and hints of yellow – ever so subtle – start to appear in the landscape. Butterfly pea blossomIn Missouri, with its middle latitudes, this usually happens a few weeks before the equinox, as August is waning into September. It is a moment that goes unnoticed by many, especially those whose lives and livelihoods have lost all connection with the natural world. To plants and animals, however, it is a clear signal – a signal to begin making preparations for the long cold months of winter that lie ahead. Plants that have not yet flowered begin to do so in earnest, while those that have shift energy reserves into developing seeds. Animals take advantage of their final opportunities to feed before enduring the scarcities of winter, digging in to sleep through them, or abandoning altogether and migrating to warmer climes. Insects begin hastily provisioning nests for their broods or laying eggs – tiny capsules of life that survive the harsh winter before hatching in spring and beginning the cycle anew.

Sand prairie in early September.Sand prairie in early October. Note abundance of splitbeard bluestem seed heads.Across much of Missouri, in the Ozark Highlands and in riparian ribbons dissecting the northern Plains, autumn brings an increasingly intense display of reds, purples, oranges, and yellows, as the leaves of deciduous hardwoods begin breaking down their chlorophyll to unmask underlying anthocyanins and other pigments. Small southern jointweedIn Missouri’s remnant prairies, seas of verdant green morph to muted shades of amber, tawny, and beige. This subtle transformation is even more spectacular in the critically imperiled sand prairies of the Southeast Lowlands, where stands of splitbeard bluestem (Andropogon ternaries – above) turn a rich russet color while fluffy, white seed heads (1st paragraph, 1st photo) appear along the length of each stem, evoking images of shooting fireworks. Small southern jointweed (Polygonella americana – right) finds a home at the northern extent of its distribution in these prairie remnants and in similar habitats in nearby Crowley’s Ridge, blooming in profusion once the cooler nights arrive. Butterfly pea (Clitoria mariana – 1st paragraph, 2nd photo) blooms add a gorgeous splash of soft purple in contrast to the muted colors of the plants around them.

Kent Fothergill, Ted MacRae, and Rich ThomaAfter first becoming acquainted with Missouri’s sand prairies this past summer, I knew a fall trip (or two) would be in order. The extensive deep, dry sand barrens were ideal habitat for sand-loving insects, including certain spring/fall species of tiger beetles that would not be active during the summer months. The cooler nights and crisp air of early fall make insect collecting extraordinarily pleasurable, so it took little effort to convince friends and colleagues Kent and Rich to join me on another excursion to these extraordinary remnant habitats, along with my (then 8 yr-old) daughter Madison (who would likely characterize this as “tallgrass” prairie). Madison MacRae, age 9 (almost)I was, as ever, on the lookout for tiger beetles; however, temperatures were cool, skies were overcast, and the fall season was just beginning, greatly limiting tiger beetle activity during this first fall visit. We did see one Cicindela formosa (big sand tiger beetle), which cooperated fully for a nice series of photographs. We also found single specimens of the annoyingly ubiquitous C. punctulata (punctured tiger beetle) and a curiously out-of-place C. duodecimguttata (12-spotted tiger beetle), which must have flown some distance from the nearest dark, muddy streambank that it surely prefers. Of greatest interest, we found two specimens of C. scutellaris (festive tiger beetle), which in this part of Missouri is represented by a population presenting a curious mix of influences from two different subspecies (more on this in a later post…). Despite the scarcity of tiger beetles, other insects were present in great diversity, some of which I share with you here.

Ululodes macleayanusThis bizarre creature, sitting on the stem of plains snakecotton (Froelichia floridana), is actually a neuropteran insect called an owlfly (family Ascalaphidae). Looking like a cross between a dragonfly and a butterfly due to its overly large eyes and many-veined wings but with long, clubbed antennae, this individual is demonstrating the cryptic resting posture they often assume with the abdomen projecting from the perch and resembling a twig. The divided eyes identify this individual as belonging to the genus Ululodes, and Dr. John D. Oswald (Texas A&M University) has kindly identified the species as U. macleayanus. As is true of many groups of insects, their taxonomy is far from completely understood. Larvae of these basal holometabolans are predaceous, lying on the ground with their large trap-jaws held wide open and often camouflaging themselves with sand and debris while waiting for prey. The slightest contact with the jaws springs them shut, and within a few minutes the prey is paralyzed and can be sucked dry at the larva’s leisure.

Ant lion, possibly in the genus Myrmeleon.Another family of neuropteran insects closely related to owlflies are antlions (family Myrmeleontidae, sometimes misspelled “Myrmeleonidae”). This individual (resting lower down on the very same F. floridana stem) may be in the genus Myrmeleon, but my wanting expertise doesn’t allow a more conclusive identification [edit 4/12/09 – John D. Oswald has identified the species as Myrmeleon immaculatus]. Strictly speaking, the term “antlion” applies to the larval form of the members of this family, all of whom create pits in sandy soils to trap ants and other small insects, thus, it’s occurrence in the sand prairie is not surprising. Larvae lie in wait beneath the sand at the bottom of the pit, flipping sand on the hapless prey to prevent it from escaping until they can impale it with their large, sickle-shaped jaws, inject digestive enzymes that ‘pre-digest’ the prey’s tissues, and suck out the liquifying contents. Finding larvae is not easy – even when pits are located and dug up, the larvae lie motionless and are often covered with a layer of sand that makes them almost impossible to detect. I’ve tried digging up pits several times and have failed as yet to find one. Larvae are also sometimes referred to as “doodlebugs” in reference to the winding, spiralling trails that the larvae leave in the sand while searching for a good trap location – these trails look like someone has doodled in the sand.

Bembix americanaThis digger wasp, Bembix americana (ID confirmed by Matthias Buck), was common on the barren sand exposures, where they dig burrows into the loose sand. Formerly included in the family Sphecidae (containing the better-known “cicada killer”), members of this group are now placed in their own family (Crabronidae). Adult females provision their nest with flies, which they catch and sting to paralyze before dragging it down into the burrow. As is common with the social hymenoptera such as bees and paper wasps, these solitary wasps engage in active parental care by providing greater number of prey as the larva grows. As many as twenty flies might be needed for a single larva. I found the burrows of these wasps at first difficult to distinguish from those created by adults of the tiger beetles I so desired, but eventually learned to distinguish them by their rounder shape and coarser, “pile” rather than “fanned” diggings (see this post for more on this subject).

Stichopogon trifasciatusRobber flies (family Asilidae) are a favorite group of mine (or, at least, as favorite as a non-coleopteran group can be). This small species, Stichopogon trifasciatus (ID confirmed by Herschel Raney), was also common on the barren sandy surface. The specific epithet refers to the three bands of alternating light and dark bands on the abdomen. Many species in this family are broadly distributed but have fairly restrictive ecological requirements, resulting in rather localized occurrences within their distribution. Stichopogon trifasciatus occurs throughout North America and south into the Neotropics wherever barren, sandy or gravely areas near water can be found. Adults are deadly predators, swooping down on spiders, flies and other small insects and “stabbing” them with their stout beak.

Chelinidea vittigerPrickly pear cactus (Opuntia humifusa) grows abundantly in the sandy soil amongst the clumps of bluestem, and on the pads were these nymphs of Chelinidea vittiger (cactus bug, family Coreidae). This wide-ranging species occurs across the U.S. and southward to northern Mexico wherever prickly pear hosts can be found. This species can either be considered a beneficial or a pest, depending upon perspective. On the one hand, it serves as a minor component in a pest complex that prevents prickly pear from aggressively overtaking rangelands in North America; however, prickly pear is used by ranchers as emergency forage, and fruits and spineless pads are also sometimes harvested for produce. In Missouri, O. humifusa is a non-aggressive component of glades, prairies, and sand and gravel washes, making C. vittiger an interesting member of the states natural diversity.

Ammophila sp., possibly A. proceraThis wasp in the genus Ammophila (perhaps A. procera as suggested by Herschel Raney) was found clinging by its jaws to a bluestem stem in the cool morning, where it presumably spent the night. One of the true sphecid (or “thread-waist”) wasps, A. procera is a widespread and common species in eastern North America. One of the largest members of the genus, its distinctive, bold silver dashes on the thorax distinguish it from most other sympatric congeners. Similar to the habits of most other aculeate wasp groups, this species captures and paralyzes sawfly or lepidopteran caterpillars to serve as food for its developing brood. Females dig burrows and lay eggs on the paralyzed hosts with which the nests have been provisioned. Adults are also found commonly on flowers, presumably to feed on nectar and/or pollen.

Dusty hog-nosed snakeRich is a bit of herpatologist, so when he brought this hog-nosed snake to our attention we all had a good time pestering it to try to get it to turn upside down and play dead. I had never seen a hog-nosed snake before but knew of its habit of rolling over and opening its mouth with its tongue hanging out when disturbed, even flopping right back over when turned rightside up or staying limp when picked up. We succeeded in getting it to emit its foul musky smell, but much to our disappointment it never did play dead, instead using its shovel-shaped snout to dig into the sand. Dusty hog-nosed snake - head closeupWe had assumed this was the common and widespread eastern hog-nosed snake (Heterodon platirhinos); however, in our attempts to turn it over I noticed its black and orange checker patterned belly. I later learned this to be characteristic of the dusky hog-nosed snake (H. nasicus gloydi), only recently discovered in the sand prairies of southeast Missouri and regarded as critically imperiled in the state due to the near complete destruction of such habitats. Disjunct from the main population further west, its continued survival in Missouri depends upon the survival of these small sand prairie remnants in the Southeast Lowlands.

The Loess Hills in Missouri

/ Ted C. MacRae / 11 Comments

The term Mountains in Miniature is the most expressive one to describe these bluffs. They have all the irregularity in shape, and in valleys that mountains have, they have no rocks and rarely timber. – Thaddeus Culbertson, missionary, 1852


One of the things I enjoy most about the natural history of Missouri is its diversity. Lying in the middle of the North American continent, it is here where the eastern deciduous forest yields to the western grasslands. Coinciding with this transition between two great biomes is a complex intersection of landforms – the northern plains, recently scoured by glaciers; the southeastern lowlands, where the great Mississippi River embayment reaches its northern extent; the Ozark Highlands, whose craggy old rocks comprise the only major landform elevation between the Appalachian and Rocky Mountains; and the eastern realm of the vast Great Plains. This nexus of east and west, of north and south, of lowlands and highlands, has given rise to a rich diversity of natural communities – 85 in all according to Paul Nelson (2005, Terrestrial Natural Communities of Missouri). Despite the overwhelming changes wrought upon Missouri’s landscape during the past 200 years, passable examples of most of these communities still exist in many parts of the state and provide a glimpse of Missouri’s rich natural heritage.

Last month I talked about the critically imperiled sand prairie community in extreme southeast Missouri. This month, we travel 500 miles to the distant northwestern corner of the state to visit another critically imperiled community – the dry loess prairie. These communities are confined to thin slivers of bluff top along the Missouri River in Atchison and Holt Counties. The bluffs on which they lie are themselves part of a unique landform called the Loess Hills. Like the sand prairies of the southeastern lowlands, this angular landscape owes its birth to the glacial advances of the Pleistocene epoch (2.5 million to 10,000 years ago), when streams of meltwater – swollen and heavily laden with finely ground sediments (i.e., glacial “flour”) – filled river valleys throughout the Midwest during Pleistocene summers. Brutal cold during winter reduced these flows to a trickle, allowing the prevailing westerly winds to pick up the sediments, left high and dry, and drop them on leeward upland surfaces across Iowa and northern Missouri. The thickest deposits occurred along the abrupt eastern border of the Missouri River valley – at least 60 feet deep, and in places up to 200 feet. Loess (pronounced “luss”) is a homogeneous, fine-grained, quartz silt – undisturbed it is highly cohesive and able to stand in near vertical bluffs. It is also extremely prone to erosion, and as a result for 10,000 years now the forces of water have reshaped the Loess Hills into the landform we see today. Loess itself is not rare – thick deposits can be found in many parts of the world and over thousands of square miles across the Midwest. It is here, however, along the western edge of Iowa and northern Missouri – and nowhere else in North America – where loess deposits are deep enough and extensive enough to obliterate any influence by the underlying bedrock and dictate the form of the landscape.

It is this form that makes the Loess Hills so unique. The depth of the soil, its cohesiveness, its natural tendency to slump on steep slopes and sheer in vertical planes, and the action of water over the past several millenia have created a landscape of narrow undulating ridges flanked by steep slopes and numerous side spurs, intricate drainages with sharply cut gullies, and long, narrow terraces called “catsteps” cutting across the steep upper hillsides. It’s a sharp, angular, corrugated landscape, stretching 200 miles north and south in a narrow band of varying width from north of Souix City, Iowa, to its southern terminus in northwestern Missouri. Its western boundary is sharply delimited by the Missouri River valley, where lateral erosion (now halted by channelization of the river) and vertical sheering have created precipitous bluff faces. The eastern boundary is harder to delimit and is dependent upon the thickness of the loess. Deposits that fall below 60 feet in depth are unable to mask and reshape the rolling terrain of the eroded glacial till lying beneath. In general, this happens at distances of only 3 to 10 miles from the western edge of the landform.

Its southern terminus in Missouri, however, is the most arbitrary boundary. Discontinuous patches of deep loess terrain do occur as far south as Kansas City, but the dry hilltop prairies, common in the north, are gradually replaced by woodland in the south and disappear completely just north of St. Joseph. It is this interdigitation of two great biomes – the great deciduous forest to the east, and the expansive grasslands stretching far to the west – that give the Loess Hills such a fascinating natural history. This is due as much to the physical character of the Loess Hills themselves as to their ecotonal position at the center of the continent. Rapid drainage of rainwater off the steep slopes combines with direct sun and prevailing southwesterly summer winds to create very dry conditions on hilltops and south and west facing slopes, especially on the steeper slopes along the landform’s western edge. Such xeric conditions favor the growth of more drought-tolerant species derived from the western grasslands. North and east facing slopes and valley floors, protected from direct sun and drying winds, are able to retain more moisture, favoring the growth of woody plant species more common in the eastern forests. Seasonal moisture also shows a north-south gradient, with southern latitudes receiving higher annual rainfall totals that also favors the growth of woody plants, while the lower rainfall totals further north result in larger, more expansive grassland habitats. The steep slopes and rapid drainage create much more xeric conditions than those found further south in the flat to rolling terrain of the unglaciated Osage Plain, resulting in a more drought-tolerant mixed-grass prairie rather than the tallgrass prairie of western and southwestern Missouri. The distribution patterns of prairie versus woodland are dynamic and ever-changing, influenced by both natural and anthropogenic processes. Climatic conditions over much of the Loess Hills are capable of supporting either community type, both of which repeatedly expand and shrink as the balance tips in favor of one versus the other. In the past, the major influence was shifting periods of greater or lesser rainfall. During drier periods, grasslands expanded and woodlands shrank, finding refuge in only the moistest streamside habitats. Wetter periods allowed woody plants to migrate out of the valleys and up the slopes, especially those facing north and east. One particular very dry “hypsithermal” began about 9,000 years ago and lasted for several thousand years. Tallgrass prairies expanded as far east as present day Ohio, and todays tallgrass praires in the eastern Great Plains were invaded by even more drought-tolerant species from the shortgrass prairies further west. Eventually the hypsithermal abated, moisture levels increased, and the grasslands retreated in the face of the advanding forest. Not all of the drought-tolerant species were driven back, however, and scattered populations of these “hypsithermal relicts” still remain on locally dry sites far to the east of their normal range of distribution. Conspicuous examples of such in Missouri’s Loess Hills are soapweed yucca (Yucca glauca var. glauca) and the leafless-appearing skeletonweed (Lygodesmia juncea) (plant above, flower right). Both of these plants are normally found further west in the mixed grass prairies of the western Great Plains but are considered endangered in Missouri due to the great rarity of the dry loess prairies on which their survival depends. (Incidentally, note the crab spider legs extending from behind the petals of the skeletonweed flower). In total, more than a dozen plant species occurring in Missouri’s dry loess prairies are listed as species of conservation concern, along with one reptile (Great Plains skink) and one mammal (Plains pocket mouse).

As is typical, the insect fauna of the Loess Hills has been far less studied than its plants, but many of the species that have been documented in its prairies also show affinity to the Great Plains fauna. Both soapweed and skeletonweed have insect associates that rely exclusively on these hosts for reproduction, and as a result they are also highly restricted in Missouri. Evidence of one of these – a tiny cynipid wasp (Anistrophus pisum) that forms small spherical galls on the stems of skeletonweed – can be seen in the photo above. However, my purpose for visiting the Loess Hills this summer was to look for the rare and possibly endangered tiger beetle, Cicindela celeripes (see this post). Cicindela celeripes has not yet been recorded from Missouri but is known to occur in the Loess Hills of southwestern Iowa, and while I have not succeeded in finding it (yet!) I did observe several adults of this unusual May beetle species, Phyllophaga lanceolata. This May beetle occurs throughout the Great Plains in shortgrass prairie communities. Larvae feed in the soil on roots of grasses and other plants, while adults feed above ground on flowers and foliage. The heavy-bodied adults are unusual in the genus due to their conspicuous covering of scales (most species of Phyllophaga are glabrous or with sparsely scattered and indistinct setae) and by being active during the day. They are also relatively poorer fliers and are thus usually observed moving about on foot – as seen with this individual who was found on bare soil below a vertical cut. This snakeweed grasshopper (Hesperotettix viridis, ID by Eric R. Eaton) is another species more typically seen in the western United States, although populations have been found from across the continent. Preferred host plants include a variety of asteraceous shrubs, but as suggested by the common name snakeweeds (Xanthocephalum spp.) are highly preferred and account for its greater abundance in the west. Populations in northern and eastern portions of its range, which would include northern Missouri, are considered subspecies pratensis, while the more southern and western populations are considered the nominotypical subspecies. Interestingly (and unlike many grasshoppers), this species is considered beneficial by ranchers, since the plants on which it prefers to feed are either poisonous to livestock or offer little nutritional value while competing with more desirable forage plants for soil moisture. While exploring the upper slopes, I encountered sporadic plants of two of Missouri’s more interesting species of milkweed – whorled milkweed (Asclepias verticillata) and green milkweed (Asclepias viridiflora), raising my hopes that I might encounter one of the many Great Plains species of milkweed beetles (genus Tetraopes). However, the only species I observed was the common milkweed beetle, Tetraopes tetrophthalmus, which occurs broadly across eastern North America on the equally broadly distributed common milkweed (Asclepias syriaca).

It is a familiar refrain, but Missouri’s dry loess hill prairie communities are critically endangered. Historically, these communities were probably never as well developed as those further north, and only a few small remnants remain today due to significant woody encroachment following decades of fire suppression. Much of this encroachment has occurred in the past 50 years – Heinman (Woody Plant Invasion of the Loess Hill Bluff Prairies. M. A. Thesis, University of Nebraska at Omaha, 1982) used aerial photographs to show a 66 percent encroachment of shrubs and trees into the loess hill mixed-grass prairies between 1940 and 1981. Additional threats include overgrazing, erosion, invasion by exotic plant species and homesite development. Fewer than 50 acres of native dry loess hill prairie remain in Missouri – only half of which are now in conservation ownership. The majority of these can be found at Star School Hill Praire and Brickyard Hill Conservation Areas in Atchison County and at McCormack Conservation Area just to the south in Holt County. Controlled burning and selective cutting are being used at these sites to control woody plant invasions, but even these management techniques present challenges. Spring burns have been shown to promote the growth of big bluestem (Andropogon gerardii), which could allow it to encroach drier areas where mid-grasses such as little bluestem (Schizachyrium scoparium) and sideoats grama (Bouteloua curtipendula) typically dominate (Rushin 2005). Increases in tall grasses could shade out and eliminate some of the rarer low-growing forbs such as downy painted cup (Castilleja sessiliflora), locoweed (Oxytropis lambertii) and low milkvetch (Astragalus lotiflorus). Fall or winter burns may be more beneficial to forbs because the plants are allowed to complete flowering and seed set, but the steep slopes on which these communities occur make erosion a potential concern. Clearly, all factors must be considered when designing management plans for this rare and significant slice of Missouri’s natural heritage.


In addition to the links and references provided above, I highly recommend Fragile Giants: A Natural History of the Loess Hills, by Cornelia F. Mutel (1989). All of the above photographs were taken at Star School Hill Prairie Conservation Area on July 12, 2008. Additional photographs of Loess Hill habitats in extreme southwestern Iowa appeared in my earlier post, The hunt for Cicindela celeripes. The plants shown in photographs 5-7 are purple praire clover (Dalea purpurea), white prairie clover (D. candida), and lead plant (Amorpha canescens), respectively. Lastly, I would like to apologize for the length of this post – a consequence of my inability to temper my utter fascination with the natural world and desire to understand the depths its connectedness.

Glades of Jefferson County

/ Ted C. MacRae / 13 Comments

We stood a moment to contemplate the sublime and beautiful scene before us, which was such an assembly of rocks and water—of hill and valley—of verdant woods and naked peaks—of native fertility and barren magnificence… – Henry Rowe Schoolcraft, 1818-1819

In the Ozark Border south of St. Louis, a series of natural openings punctuate the dry, rocky forests of Jefferson County. Commonly called “glades” or “cedar glades,” these islands of prairie in a sea of forest are home to plants and animals more commonly associated with the Great Plains region further to the west. Extending in a narrow arc from central Jefferson County east and south into northern Ste. Genevieve County, these glades occur most commonly on south and southwest-facing slopes below forested ridges and are characterized by thin soils and exposed dolomite bedrock of Ordovician age. Glades are, in fact, a common natural feature throughout much of the Ozark Highlands, an extraordinary plateau where the great eastern deciduous forest begins to yield to the western grasslands. A much more extensive system of dolomite glades occurs in the White River Hills of southwest Missouri, where they often extend up steep slopes and over the tops of knobs to form what Schoolcraft called “naked peaks” and are now called “balds” (and spawning the “Baldknobbers” of Branson fame). Additional glade complexes occur throughout the Ozark Highlands on different rock substrates – igneous glades abound in the St. Francois Mountains, sandstone glades dot the Lamotte landscape in Ste. Genevieve County and the northern and western Ozarks, limestone glades can be found in the northern Ozarks near Danville and Lake of the Ozarks, and chert glades occur in extreme southwest Missouri. These different glade systems share a common feature – shallow soils where tree establishment is limited due to summer moisture stress. They differ vegetationally, however, due to differences in hydrology and soil chemistry as a result of their different substrates. Floristically, dolomite glades exhibit a high degree of diversity relative to other glade types.

The term “glade” is derived from the Old English “glad,” meaning a shining place – perhaps the early settlers found their open landscapes a welcome respite after emerging from the confining vastness of the eastern deciduous forest. Whatever the meaning, the glades of Jefferson County hold a special place in my heart, for I “grew up,” entomologically speaking, in those glades. As a young entomologist, fresh out of school, I spent many a day scrambling through the glades and surrounding woodlands. It was here where my interest in beetles, especially woodboring beetles, was born and later grew into a passion. For eight years I visited these glades often – attracted by the extraordinary diversity of insects living within the glades and congregating around its edges. My earliest buprestid and cerambycid papers contain numerous records from “Victoria Glades” and “Valley View Glades” – the two best-preserved examples of the glades that once occurred extensively throughout the area (more on this later). My visits to these glades ended in 1990 when I moved to California, and although I moved back to the St. Louis area in 1995, the focus of my beetle research has more often taken me to places outside of Missouri. It had, in fact, been some 10 years since my last visit to these glades until last week, when I was able to once again spend some time in them.

Ozark glades differ from the true cedar glades of the southeastern U.S. in that they are not a climax habitat – they depend upon periodic fires to prevent succession to forest. Some recent authors have suggested the term “xeric dolomite/limestone prairie” be used to distinguish the fire-dependent glades of the Ozarks from the edaphic climax cedar glades of the southeast (Baskin & Baskin 2000, Baskin et al. 2007). Fires have been largely suppressed throughout Missouri since European settlement, leading to encroachment upon the glades by eastern red-cedar (Juniperus virginiana). Pure stands of red-cedar have developed on many former glades, crowding out the herbaceous plants that depend upon full sun and leading to soil formation that supports further encroachment by additional woody plant species such as post oak (Quercus stellata), blackjack oak (Q. marilandica), flowering dogwood (Cornus florida), and fragrant sumac (Rhus aromatica) from the surrounding woodlands. Fire has returned to many of the Ozark glades situated on lands owned or managed by state and federal agencies such as the Missouri Department of Conservation, Missouri Department of Natural Resources, and U.S. Forest Service, as well as private conservation-minded organizations such as The Nature Conservancy. These agencies have begun adopting cedar removal and fire management techniques to bring back the pre-settlement look and diversity of the Ozark Glades. This is particularly true at Victoria Glades and Valley View Glades, the two largest and most pristine examples of the Jefferson County dolomite glade complex. Fires have been used to kill small red-cedars in the glades, as well as rejuvenate their herbaceous plant communities. Larger red-cedar trees are not killed outright by fire and must be removed by chainsaws. This above distant view of the TNC parcel at Victoria Glades shows many such burned red-cedars. The glades themselves are not the only habitat to benefit from this aggressive management – when I was doing my fieldwork here in the 1980’s the surrounding woodlands were a closed post oak forest bordered by fragrant sumac and with little or no understory in the interior. The photo at right now shows an open savanna with a rich understory of not only sumac and other shrubs, but also many herbaceous plants as well such as black-eyed susan (Rudbeckia hirta) and American feverfew (Parthenium integrifolium). Such open woodland more closely resembles what Schoolcraft saw across much of the Ozarks during his journey almost two centuries ago.

Victoria and Valley View Glades are dominated by little bluestem (Schizachyrium scoparium), Indian grass (Sorghastrum nutans), big bluestem (Andropogon gerardii) and prairie dropseed (Sporobolus heterolepis). A smaller but highly charismatic non-grass flora is also found on the glades – species such as Missouri evening primrose (Oenethera macrocarpa) (left), pale purple coneflower (Echinacea simulata) (pictured above and below), and prairie dock (Silphium terebinthinaceum) not only add beautiful color but also support both vertebrate and invertebrate wildlife. The Fremont’s leather flower (Clematis fremontii) is a true endemic, occurring only in this part of Missouri and entirely dependent upon these glades for its survival. Less well studied is the vast insect fauna associated with the glades. It is here where I first discovered the occurrence of Acmaeodera neglecta in Missouri. This small jewel beetle is similar to the broadly occurring A. tubulus but at the time was known only from Texas and surrounding states. In collecting what I thought were adults of A. tubulus on various flowers in the glades, I noticed that some of them were less shining, more strongly punctate, and exhibited elytral patterning that was often coalesced into longitudinal “C-shaped” markings rather than the scattered small spots typical of A. tubulus. These proved to be A. neglecta, which I have since found on many glade habitats throughout the Ozark Highlands. Both species can be seen in this photo feeding on a flower of hairy wild petunia (Ruellia humilis) – the lower individual is A. neglecta, while the upper individual and two inside the flower are A. tubulus. Another interesting insect-plant association I discovered at these glades was the strikingly beautiful Dicerca pugionata – another species of jewel beetle – and its host plant ninebark (Physocarpus opulifolius). Only a single Missouri occurrence had been reported for D. pugionata, despite the common occurrence of its host plant along rocky streams and rivers throughout the Ozark Highlands. This plant also grows at Victoria and Valley View Glades along the intermittent streams that drain the glades and in the moist toeslopes along the lower edges of the glades where water that has percolated through the rocks and down the slopes is forced to the surface by an impermeable layer of bedrock. Unlike the tall, robust, lush plants that can be found in more optimal streamside habitats with good moisture availability, the ninebark plants of Victoria and Valley View Glades are small and scraggly, usually with some dieback that results from suboptimal growing conditions. I surmise these plants have reduced capabilities for fending off attacks by insects, including D. pugionata, and as a result a healthy population of the insect thrives at these glades. Some might be inclined to call this beetle a pest, threatening the health of one of the glade’s plants. In reality, the insect finds refuge in these glades – unable to effectively colonize the vast reserves of healthy plants that grow along streams throughout the rest of the Ozarks, it strikes a tenuous balance with plants that are themselves on the edge of survival.

Despite the success in moving Victoria and Valley View Glades closer to their pre-settlement character, the integrity of these areas continues to be challenged. Poachers take anything of real or perceived value, and ATV enthusiasts view the open spaces as nothing more than tarmac. Pale purple coneflower occurs abundantly on these Jefferson County glades (but sparingly in other habitats – primarily rocky roadsides), where they provide a stunning floral display during June and sustain innumerable insect pollinators. Plants in the genus Echinacea also have perceived medicinal value, as herbalists believe their roots contain an effective blood purifier and antibiotic. There are no conclusive human clinical trials to date that fully substantiate this purported immune stimulating effect (McKeown 1999). Nevertheless, demand for herbal use has skyrocketed in recent decades, prompting widespread illegal harvesting of several coneflower species throughout their collective range across the Great Plains and Ozark Highlands. I witnessed massive removals of this plant from both Victoria and Valley View Glades during the 1980’s, but the pictures I took this year suggest that such illegal harvests have been suppressed and that the populations at both sites are recovering nicely.

The same cannot be said for the practice of rock flipping. This was a problem I witnessed back in the 1980’s, and I saw fresh evidence of its continued occurrence at both sites. The thin soils and sloping terrain leave successive layers of dolomite bedrock exposed, the edges of which shatter from repeated freeze-thaw cycles to create rows of loose, flat rocks along the bedrock strata. Lizards, snakes, tarantulas, and scorpions find refuge under these loose rocks, only to be ripped from their homes by flippers and transferred to a dark, cold terrarium to endure a slow, lingering death. As if poaching the glade’s fauna and watching them slowly die isn’t bad enough, the flippers add insult to injury by not even bothering to replace the rock in its original position after stealing its inhabitant, amounting to habitat destruction three times greater than the area of the rock itself. Firstly, the habitat under the rock is destroyed by sudden exposure of the diverse and formerly sheltered microfauna to deadly sunlight. Next, the habitat onto which the rock is flipped is also destroyed, as the plants growing there begin a slow, smothering death. Lastly, the upper surface of the rock, sometimes colonized by mosses and lichens that might have required decades or longer to grow, usually ends up against the ground – its white, sterile underside becoming the new upper surface. Rock flipper scars take years to heal, and nearly all of the flat, loose rocks seen in the more accessible areas of the glades exhibit scars of varying ages next to them. If a scar is fresh (first photo), I generally return to the rock to its original position – the former inhabitants cannot be brought back, but at least the original habitats are saved and can recover quickly. However, if a scar is too old (2nd photo) it is best to leave the rock in its new position – replacing it only prolongs the time required for recovery.

Even more damaging is ATV use. Herbaceous plants and thin soils are no match for the aggressive tread of ATV tires, and it doesn’t take too many passes over an area before the delicate plants are killed and loose soils ripped apart. I witnessed this become a big problem particularly on Victoria Glades during the 1980’s – actually finding myself once in a face-to-face confrontation with an ATV’er. Fortunately, he turned tail and ran, and it appears (for now) that such abuses have stopped, as I saw no evidence of more recent tracks during this visit. But the scars of those tracks laid down more than two decades ago still remain painfully visible. I expect several more decades will pass before they are healed completely.

My return to Victoria and Valley View Glades was a homecoming of sorts, and I was genuinely pleased to see the progress that has been made in managing these areas while revisiting the sites where my love affair with beetles was first kindled. Sadly, however, the larger glade complex of Jefferson County continues to deteriorate. Restoration acreage aside, red-cedar encroachment continues unabated on many of the remaining glade parcels – large and small – that dot the south and southwest facing slopes in this area. It has been conservatively estimated that as much as 70% of the original high quality glades in Missouri are now covered in red-cedar. Many of these are privately held – their owners either do not recognize their ecological significance or are loathe to set fire to them. An example can be seen in the picture here – this small parcel is part of the Victoria Glades complex but lies on private land in red-cedar choked contrast to the Nature Conservancy parcel immediately to the south. Small numbers of herbaceous plants persist here, but without intervention by fire or chainsaw their numbers will continue to dwindle and the glade will die. Aside from the loss of these glades, the continuing reduction of glade habitat complicates management options for preserved glades as well. Many glade associated invertebrates are “fire-sensitive” – i.e., they overwinter in the duff and leaf litter above the soil and are thus vulnerable to spring or fall fires. While these fires are profoundly useful for invigorating the herbaceous flora, they can lead to local extirpation of fire-sensitive invertebrate species within the burn area. Recolonization normally occurs quickly from unburned glades in proximity to the burned areas but can be hampered if source habitat exists as small, highly-fragmented remnants separated by extensive tracts of hostile environment. Grazing also continues to threaten existing remnants in the Jefferson County complex. Grazing rates are higher now than ever before, with greater negative impact due to the use of fencing that prevents grazers from moving to “greener pastures”. Over-grazing eliminates native vegetation through constant depletion of nutrient reserves and disturbance of the delicate soil structure, leading to invasion and establishment of undesirable plant species. Eventually, the glade becomes unproductive for pasture and is abandoned – coupled with fire suppression this leads to rapid woody encroachment. It is truly depressing to drive through Jefferson County and recognize these cedar-choked glades for what they were, able to do nothing but watch in dismay as yet another aspect of Missouri’s natural heritage gradually disappears. The continued loss of these remnant glades makes careful use of fire management on Victoria and Valley View Glades all the more critical – ensuring that a patchwork of unburned, lightly burned, and more heavily burned areas exists at a given time will be critical for preventing invertebrate extirpations within these managed areas.

I close by sharing with you a few more of the many photographs I took during this visit – stiff tickseed (Coreopsis palmata), three-toed box turtle (Terrapene carolina triunguis), climbing milkweed (Matelea decipiens – see the excellent post about this plant on Ozark Highlands of Missouri), downy phlox (Phlox pilosa), green milkweed (Asclepias viridiflora), and a “deerly” departed native browser.

Pickle Springs Natural Area

/ Ted C. MacRae / 3 Comments

Pickle Springs Natural Area lies in Ste. Genevieve County, about an hour south of St. Louis. Like Hawn State Park, the geology of this area and its effect on the flora have resulted in a unique collection of geologic features and plants found in few other places. The Lamotte sandstone outcrops that dot the landscape were formed nearly half a billion years ago when sand deposited in an extensive maze of braided river channels was cemented and buried under younger layers of limestone and dolomite formed from deposits on the floors of ancient seas that covered the interior of the continent. Later, the periods of uplift that created the St. Francois Mountains and resulting erosion of overlying strata once again exposed the sandstones at the surface. Millions of years of water, ice, rain, wind, and plants have further shaped the exposed sandstones, creating fanstastic shapes and formations and cool, deep canyons. The weathered sandstone created acid soils which support many unique plants. During the ice ages, northern plants and animals moved into the area ahead of the advancing glaciers. Mammoths roamed the landscape grazing on the northern vegetation supported by the area’s acid soils. Eventually the ice retreated, and so did the mammoths. But many of the plants remained – able to hang on in the cool, moist canyons long after the mammoths that once roamed these canyons disappeared. Because of this unique concentration of rare plants and geologic features, the area has been designated a Missouri Natural Area and a National Natural Landmark.

Yesterday I hiked the aptly-named ‘Trail Through Time’ with my family. This 2-mile trail is one of the most “feature-packed” trails in the state, with something to look at around almost every bend. Almost immediately the trail leads to the Slot, the result of a vertical fracture in the Lamotte sandstone that was loosened by leaching and then widened by erosion. The unique partridge berry (Mitchella repens) was seen on the moist, vertical walls of the rock, growing among strange holes, pockets, and ridges that formed as a result of the sand grains being variably cemented.


A short distance from The Slot lie Cauliflower Rocks – large moundlike formations (also called hoodoos or rock pillars) formed from jointed or fractured sandstone that undergoes deep solutional weathering followed by erosion and weather-mediated shaping. Hoodoos occur primarily in this type of rock due to its granular, variably cemented and cross-bedded matrix.


On the south side of Cauliflower Rocks lies a special type of buttress arch called Double Arch. It occurs at almost a right angle to the adjacent rock outrcrops, suggesting formation along a set of fractures running perpendicular to the main fracture trend of the area, but the precise details of its formation remain a mystery.


After leaving Cauliflower Rocks the trail descends steeply into a deep valley, at the bottom of which lies Pickle Creek just below its origin in a box canyon south of the Natural Area. Lush vegetation in this cool, moist valley contrasts with the stark rocks seen earlier.


The creek is fed by a series of seeps, allowing the valley to remain moist even during the dry summer months, and along with the acid soils support a unique plant community. Lush colonies of ferns (I believe this is Polypodium virginianum L.) covered the rocks adjacent to the creek…


…while this rattlesnake plantain orchid (Goodyera pubescens) was seen in a colony growing at the base of a black oak tree (Quercus velutina) just above the creek.


Mosses and lichens were also abundant in the valley. This little hair cap moss (Polytrichum sp.) with its distinctive fruiting structures was growing in a colony at the base of another black oak tree. The members of this genus prefer acidic environments.


Further ahead, along Bone Creek, several colonies of wooly aphids (family Aphididae) were seen on the branches of a small hop hornbeam tree (Ostrya virginiana).


The highlight of the hike had to be in Spirit Canyon at Owl’s Den Bluff. The horizontal layers of sandstone, each deposited on the steep downstream slopes of sandbars, are clearly visible in the towering bluff face. At the bottom lie bluff shelters – formed where lower sandstone layers collapse due to weathering or leaching, and where native Americans almost surely camped out. The sun never reaches parts of these shelters, providing ideal conditions for a variety of mosses and liverworts – many of which are known only from this area. Fallen boulders and collapsed portions of the bluff face provided photo opps for the daring…


…and good exploring for the nimble.


By now, the trail has passed the halfway point and is looping back to the west, where it ascends to Dome Rock Overlook. Along the way, a fascinating variety of lichens, including reindeer lichen, covers the forest floor where they are supported by the acid soils.


Dome Rock Overlook is a the largest hoodoo complex in the Natural Area. The thin soils and exposed conditions create a harsh, dry, windswept environment that only the hardiest of plants can withstand. Only a few small blackjack oaks (Quercus marilandica), shortleaf pines (Pinus echinata), and farkleberry (Vaccinium arboreum) survive here. Despite their small size, some of the trees growing here are at least 150 years old.


The trail descends from Dome Rock Overlook and passes underneath, providing spectacular views of the sheer rock face below the overlook. The trail completes its descent back into Pickle Creek Valley, where Pickle Spring can be seen. This small, permanent spring – an unusual feature in sandstone where seeps are more common – was an important source of water for early settlers.


Further along the trail lies one of the areas most unusual features – Rockpile Canyon – formed some 50 years ago (a fraction of a second in geologic time) when part of a sandstone bluff collapsed in a rumble, leaving behind a sheer bluff face and a jumbled pile of large boulders. A short spur in the trail leads to the head of a small box canyon, where some of the 20+ ice age relict plant species can be seen growing in the acid soils and cool, moist canyon walls.

Near the end of the loop lies Piney Glade, an area where the exposed sandstone bedrock once again creates a dry, harsh environment. Poverty grass and little bluestem grow in small, shallow pockets of soil scattered amongst stunted shortleaf pines and blackjack oaks – creating a small prairie surrounded by a sea of forest. All three forms of lichens can be found on the rocks and soils of the glade – the aptly named crustose lichens cling tightly to rock surfaces amongst foliose (leafy) and fruticose (branched) lichens.