Backyard gems

I’ve been fortunate to have the chance to travel far and wide in my searches for insects—from the Gypsum Hills of the Great Plains and Sky Islands of the desert southwest to the subtropical riparian woodlands of the Lower Rio Grande Valley, tropical thorn forests of southern Mexico and veld of southern Africa. No matter how far I travel, however, I’m always happy to return to the Missouri Ozarks. It is here where I cut my entomological teeth so many years ago, and though I’ve now scrabbled around these ancient hills for more than three decades it continues to satisfy my thirst for natural history. Though not nearly as expansive as the Great Plains, there are nevertheless innumerable nooks and crannies nestled in the Ozarks, and I find myself constantly torn between looking for new spots (it would take several lifetimes to find them all) and going back to old favorites. Living in the northeastern “foothills” in the outskirts of St. Louis provides an ideal vantage for exploration; however, sometimes I am truly amazed at the natural history gems that can be found within a stone’s throw from my house. Some examples I’ve featured previously include Shaw Nature Reserve, home to a hotspot of the one-spotted tiger beetle, Castlewood State Park, where I found a gorgeously reddish population of the eastern big sand tiger beetle, and Victoria Glades Natural Area, site of the very first new species (and perhaps also the most beautiful) that I ever collected.

Englemann Woods Natural Area | Franklin Co., Missouri

Today I found another such area—Englemann Woods Natural Area, and at only 5 miles from my doorstep it is the closest natural gem that I have yet encountered. One of the last old-growth forests in the state, its deep loess deposits on dolomite bedrock overlooking the Missouri River valley support rich, mesic forests on the moister north and east facing slopes and dry-mesic forests on the drier west-facing slopes dissected by rich, wet-mesic forests with their hundreds-of-years-old trees. A remarkable forest of white oak, ash, basswood and maple in an area dominated by monotonous second-growth oak/hickory forests.

Englemann Woods Natural Area

Steep north-facing slopes border the Missouri River valley.

It is not, however, the 200-year-old trees that will bring me back to this spot, but rather the understory on the north and east-facing slopes. Here occur some of the richest stands of eastern hornbean (Ostrya virginiana) that I have ever seen. This diminutive forest understory inhabitant is not particularly rare in Missouri, but as it prefers rather moist upland situations it is not commonly encountered in the dry-mesic forests that dominate much of the Ozarks. Stands of this tree, a member of the birch family (Betulaceae) are easy to spot in winter due to their habit of holding onto their dried canopy of tawny-brown leaves (see photo below).

Englemann Woods Natural Area

Rich stands of eastern hornbeam (Ostrya virginiana) dominate the north- and east-slope understory.

Why am I so interested in this plant? It is the primary host of the jewel beetle species Agrilus champlaini. Unlike most other members of the genus, this species breeds in living trees rather than dead wood, their larvae creating characteristic swellings (galls, if you will) on the twigs and stems as they spiral around under the bark feeding on the cambium tissues before entering the wood to pupate and emerge as adults in spring. This species is known in Missouri from just two specimens, both collected by me way back in the 1980s as they emerged from galls that I had collected during the winter at two locations much further away from St. Louis. The presence of this rich stand of hornbeam just 5 miles from my home gives me the opportunity to not only search the area more thoroughly to look for the presence of galls from which I might rear additional specimens, but also to look for adults on their hosts during spring and (possibly, hopefully) succeed in photographing them alive.

Englemann Woods Natural Area

Inside the “hornbeam forest.”

Another “draw” for me is the restoration work that has begun on some of the west-facing slopes in the areas. Pre-settlement Missouri was a far less wooded place than it is today, as evidenced by the richly descriptive writings penned by Henry Schoolcraft during his horseback journey through the Ozarks in the early 1800’s. At the interface between the great deciduous forests to the east and the expansive grasslands to the west, the forests of Missouri were historically a shifting mosaic of savanna and woodland mediated by fire. Relatively drier west-facing slopes were more prone to the occurrence of these fires, resulting in open woodlands with more diverse herbaceous and shrub layers. At the far extreme these habitats are most properly called “xeric dolomite/limestone prairie” but nearly universally referred to by Missourians as “glades”—islands of prairie in a sea of forest! I have sampled glades extensively in Missouri over the years, and they are perhaps my favorite of all Missouri habitats. However, it is not future glades or savannas that have me excited about Englemann Woods but rather the availability of freshly dead wood for jewel beetles and longhorned beetles resulting from the selective logging that has taken place as a first step towards restoration of such habitats on these west-slopes. The downed trees on these slopes and subsequent mortality of some still standing trees that is likely to result from the sudden exposure of their shade adapted trunks to full sun are likely to serve as a sink for these beetles for several years to come. I will want to use all the tools at my disposal for sampling them while I have this opportunity—beating, attraction to ultraviolet lights, and fermenting bait traps being the primary ones. It looks like I’d better stock up on molasses and cheap beer!

Englemann Woods Natural Area

Restoration efforts on the west-facing slopes begins with selective logging.

Eastern red-cedar (Juniperus virginiana) is native to Missouri, but in our time it has become a major, invasive pest tree. The suppression of fire that came with settlement also freed this tree from a major constraining influence on its establishment in various habitats around the state, primarily dolomite/limestone glades. Nowadays most former glade habitats, unless actively managed to prevent it, have become choked with stands of this tree, resulting in shading out of the sun-loving plants that historically occurred much more commonly in the state. Untold dollars are spent each year by landscape managers on mechanical removal and controlled burns to remove red-cedar and prevent its reestablishment in these habitats. There is one habitat in Missouri, however, in which eastern red-cedar has reigned supreme for centuries or possibly millenia—dolomite/limestone bluff faces.

Juniperus virginiana

Craggly, old Eastern red-cedars (Juniperus virginiana) cling tenaciously to the towering dolomite bluffs.

With little more than a crack in the rock to serve as a toehold, red-cedars thrive where no other tree can, growing slowly, their gnarled trunks contorted and branches twisted by exposure to sun and wind and chronic lack of moisture. Some of the oldest trees in Missouri are red-cedars living on bluffs, with the oldest example reported coming from Missouri at an incredible 750–800 years old. There is something awe-inspiring about seeing a living organism that existed in my home state before there were roads and cars and guns. These ancient trees are now an easy drive from my house (though a rather strenuous 300-ft bushwhacking ascent to reach the bluff tops)—they seem ironically vulnerable now after having endured for so long against the forces of nature. For me, they will serve as a spiritual draw—a reason to return to this place again regardless of what success I might have at finding insects in the coming months.

Juniperus virginiana

This tree may pre-date Eurpoean settlement.

Aplectrum hyemale

Adam-and-Eve orchid (Aplectrum hyemale).

Copyright © Ted C. MacRae 2013

Trees of Lake Tahoe – The Deciduous Trees

Alder, Maple, and Nuttall’s Flowering Dogwood make beautiful bowers over swift, cool streams at an elevation of from 3000 to 5000 feet, mixed more or less with willows and cottonwood; and above these in lake basins the aspen forms fine ornamental groves, and lets its light shine gloriously in the autumn months.–John Muir, The Mountains of California (1894).

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This is the third installment of a “Trees of Lake Tahoe” series summarizing the trees of Tahoe Basin. The basin forests are, of course, dominated by a diverse assemblage of conifers – eleven species in all.  These were covered in parts 1 (Trees of Lake Tahoe – The Pines) and 2 (Trees of Lake Tahoe – The “Other” Conifers ) of this series.  Yet, despite this coniferous domination, the 14 species of deciduous trees¹ that occur in the Tahoe Basin is three more than the number of coniferous tree species.  These deciduous tree species will be covered in this third and final part, including the nine species I was able to locate on my recent visit to the area back in mid-March.  Because of the timing of that trip, the trees will be discussed from a decidedly wintertime perspective that makes species identifications a little more challenging compared to the coniferous species.

¹ Admittedly, I use the term “tree” in the broadest sense, since many of these species might better be described as “tree-like shrubs” or “shrubby trees,” often representing only the largest examples of genera whose members include a number of true shrubs.  Only a handful of these species routinely form large, unmistakably tree-like forms, the largest of which still pale in comparison to the coniferous giants that dominate the basin.

Family SALICACEAE

This family of dioecious plants (male and female flowers on separate plants) is represented in the Tahoe Basin by two genera.  Two species of Populus occur here, and both decidedly trees in form.  Most of the nine species of Salix that grow in the basin grow only as shrubs, while two of them sometimes form distinct trees.

Quaking aspen (Populus tremuloides)

…in winter, after every leaf has fallen, the white bark of the boles and branches seen in mass seems like a cloud of mist that has settled close down on the mountain, conforming to all its hollows and ridges like a mantle, yet roughened on the surface with innumerable ascending spires.–John Muir, Steep Trails (1918).

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Quaking aspen is one of the most unmistakable trees of the Tahoe Basin – regardless of the season.  Famous for its shimmering foliage during summer and blazing fall colors, it is equally distinctive during winter when its smooth, creamy, greenish-white trunks stand in stark, leafless contrast to the dark green coniferous foliage that cloaks the landscape.  Thick stands of this species are common in moist meadows and stream margins, with stands typically representing clonal colonies of genetically identical trees sprouting from a common root mat.  Although another species of Populus does occur in the basin (black cottonwood – see below), that species is not nearly as abundant as quaking aspen and lacks its distinctive smooth bark.

The second photo above shows some of the few, still-clinging leaves that I found, unremarkable in senescence but showing the flattened petioles that cause to summertime leaves to flutter and quiver incessantly with the summer breezes, alternately flashing their bright green upper surface and silvery underside.

Black cottonwood (Populus balsamifera ssp. trichocarpa)

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Black cottonwood is the largest American Populus and the tallest non-conifer in western North America.  Growing throughout the cool, moist Pacific Northwest, it is at its elevational limit in the Sierra Nevada along moist streams and lakeside habitats in the lower Tahoe Basin. The wonderfully knowledgeable Forest Service worker, who helped me greatly in my quest to locate all of the basin’s conifers, was skeptical about my chances of finding this species; however, while hiking the Rubicon Trail at Emerald Bay State Park I spotted the unmistakable, deeply furrowed, gray bark of this close relative of our own eastern cottonwood (Populus deltoides).  Examining the twigs revealed the large, pointed buds, sticky with resin, and a few clinging leaves whose wide, ovate shape confirmed the species’ identity.  It was the only black cottonwood I saw in the basin, although surely others exist throughout the basin at lakeside elevations.

Willows (Salix spp.)

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As a group, willows are easily distinguished from the other deciduous trees and shrubs that occur in the Tahoe Basin.  However, discriminating among the several species can be quite difficult, even for trained botanists.  Winter is not the best time to try to identify willows, as many species are distinguished by characters of the foliage and flowers.  In some cases, examination of both male and female flowers is required – frustrating since they are borne on separate plants!  Wintertime characters normally useful for other plants such as bark and twig color are rarely informative for different species of willow, and even growth habit as trees or shrubs can vary greatly within species depending on elevation and available moisture.  All of this is a long-winded way of saying I don’t know which or how many species of willow I observed in the Tahoe Basin.

p1020705_2p1020707_2According to Graf (1999), there are nine species of willow in the Tahoe Basin; however, only two of them are trees – the abundant shining willow (S. lucida spp. lasiandra), and the more drought-tolerant Scouler’s willow (S. scouleriana).  The remaining seven species are shrubs that rarely exceed 10-12 feet in height.  Indeed, one of them – arctic willow (Salix arctica) – grows no more than 4 inches tall, occurring in seepy slopes and along lake and stream margins in the subalpine zone at Carson Pass.  Most of the willows I observed were at lower elevation along the shore of Emerald Bay and in the wet meadows around South Lake Tahoe and Spooner Lake and were growing as large shrubs or small trees and exhibited either bright yellow or red bark on the year-old branches, turning to smooth gray on older branches.  I don’t know whether these represent one or more species, or if they even represent one of the two arborescent species, but I suspect the yellow-twigged species may represent Lemmon’s willow (S. lemmonii), one of the shub species and Tahoe’s most common willow.  Perhaps a stretch goal for next year’s trip could be to find and distinguish all nine Tahoe Basin willow species, but realistically I would settle for knowing for sure what species the plants in these photographs represent (although I definitely would like to find the diminutive arctic willow).

Family BETULACEAE

Like the Salicaceae, plants in this family have male and female flowers on separate structures called catkins, but the plants themselves are monoecious (both sexes on the same plant).  Two genera – Alnus and Betula – occur in the basin, each represented by one species.

Mountain alder (Alnus incana ssp. tenuifolia)

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Like the willows, mountain alder is another deciduous plant that straddles the line between tree and shrub, and as is typical of most species in these two plant families (Salicaceae and Betulaceae) the species shows a high affinity for moist sites along stream and lake margins and on seepy north- and east-facing slopes.  The largest specimens I saw, as pictured above left, were found growing on the granite sand beaches along the Rubicon Trail on the western shore of Emerald Bay in Emerald Bay State Park.  Like alders anywhere, this species is immediately recognizeable in winter due to the persistent woody cones that represent the previous year’s female catkins.  Another larger species of alder, white alder (A. rhombifolia), occurs in the Sierra Nevada, but it is not clear to me whether this species actually occurs in the Tahoe Basin proper.  Graf (1999) does not include it in his rather comprehensive treatment of Tahoe Basin plants, but Peterson & Peterson (1975) and Quinn (2006) both list it from the basin (although rare). 

Water birch (Betula occidentalis)

I did not observe this species, which Graf (1999) records from Carson Pass.  The only birch occurring in the Sierra Nevada, it is more common outside the basin proper on the eastern slopes above the burning sagebrush plains.  Like alder, separate male and female catkins are borne on the same tree; however, the female catkins of birch are solitary rather than clustered and disintegrate when ripe rather than persisting as woody cones.

Family FAGACEAE

This family contains the über diverse genus Quercus – represented in California by 20 species.  However, of the five arborescent oaks that occur in the Sierra Nevada, only one has successfully penetrated the high elevations of the Tahoe Basin. A second species of Quercus also inhabits this montane region but grows exclusively as a low shrub, and another shrub in the related genus Chrysolepis also grows here – these two latter species will be treated more fully in a future post.

Canyon live oak (Quercus chrysolepis)

The trunk was all knots and buttresses, gray like granite, and about as angular and irregular as the boulders on which it was growing—a type of steadfast, unwedgeable strength.–John Muir, The Mountains of California (1894).

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This is one of North America’s most variable oaks, exhibiting extreme variability in leaves and fruit and developing as either a tree or a shrub, depending upon the site where it grows. Slow growing and solid, it does best in sheltered locations, where it can develop an impressive, spreading crown and live a hundred years or more. On exposed slopes, it takes on a shorter, shrubbier aspect (above left) or forms dense thickets (above right).  I saw most of this species at lower elevations within the basin – along the Vikingsholm Trail in Emerald Bay State park leading down to the west shore of Emerald Bay.

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The leaves of this evergreen species are bluish green with numerous golden glandular hairs when young and becoming dull gray and smooth with age. Although there are no other arborescent oaks at this elevation with which it can be confused, I did find growing alongside it the strictly montane and shrubby huckleberry oak (Q. vaccinifolia).  The somewhat smaller, mostly entire leaves were the only indication it was not merely a shrub form of canyon live oak, and further study revealed that the two species can be distinguished by the presence of multiradiate glandular hairs on both leaf surfaces of canyon live oak.  These two species are closely related (both are in the Protobalanus – or “golden oak” – section of the genus), and widespread hybridization has apparently been documented in this part of the Sierra Nevada where the two species’ distributions overlap (Nixon 2002).

Family ROSACEAE

This large family of dioecious plants with usually pentamerous radial flowers is represented in the Tahoe Basin by nearly three dozen mostly perennial shrubs.  Six of these species, representing the genera Amelanchier, Cercocarpus, Prunus and Sorbus, sometimes develop a tree form.

Cherry (Prunus sp.)

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Two species of Prunus – bitter cherry (P. emarginata) and western chokecherry (P. virginiana var. demissa) – occur in the Tahoe Basin, both growing as either shrubs or small trees.  I cannot say for sure which species is represented in these photographs (taken on the slopes above Emerald Bay at Emerald Bay State Park), as the two species are best distinguished by subtle differences in their flowers and foliage.  Bitter cherry is apparently common in the Tahoe Basin and has bark that is smooth and dark brown, while chokecherry is more of a foothill species that is uncommon on the western shore (where these photos were taken) and has more grayish brown and somewhat scaly bark.  I can go either way with bark color based on these photos, so I’ll forgo an ID for the time being and seek to follow up during my next visit.  A third species of Prunus, the strictly shrubby desert peach (P. andersonii), formerly occurred at low elevations around the south shore, but it is now considered to be extirpated from the basin.

Mountain ash (Sorbus californica)

While hiking the Rubicon Trail in Emerald Bay State Park, I spotted a single, small tree with distinctive, large winter buds that reminded me immediately of the ornamental species mountain ash (Sorbus aucuparia) from my former days as a nursery inspector.  This thought seemed to be confirmed when I found a senesced but still attached leaf, pinnately compound with nine ovate, toothed leaflets.  However, my pocket copy of Native Trees of the Sierra Nevada (Peterson & Peterson 1975) included no species of Sorbus, and I concluded it must be something else.  This lone tree was located in deep shade within the white fir forest near the western shore of Emerald Bay, so I opted to find another tree in better lit conditions for taking photos – unfortunately, no other trees of this species were found.  Once I got back home, I was happy to find Sorbus californica listed in my just purchased copy of Graf (1999).  This species has attractive white flowers in small panicles during the summer that give rise to bright red berries during fall and is apparently common in mid- to higher-elevation riparian communities around the lake.

Serviceberry (Amelanchier spp.)
Curl-leaf mountain mahogany (Cercocarpus ledifolius)

I did not locate either of the two species of serviceberry that occur in the Tahoe Basin, the common serviceberry (Amelanchier utahensis) and the more localized glabrous serviceberry (A. alnifolia var. pumila).  Being highly familiar with our eastern species, A. arborea (just recently finished flowering), I suspect either of these species would be readily recognized, even in winter, by their smooth, silvery-gray bark and shrubby, small-tree form.  I also did not see curl-leaf mountain mahogany (Cercocarpus ledifolius), another species that barely qualifies as a small tree.  It is apparently more at home on the dry eastern flank of the Sierra Nevada but can be found within the basin proper sporadically in the southwest and along the southeastern lake shore and more commonly on dry slopes in the far north and south of the basin.  I have collected a number of woodboring beetles from mountain mahogany across the southwestern U.S. from the mountains of southern California to the Chisos Mountains of Texas.

Family ACERACEAE

The single North American genus, Acer, is represented in California by four species, three of which occur in the Sierra Nevada but only one occurring in the Tahoe Basin.  Plants in this family are closely related to the Hippocastanaceae, represented in the Sierra Nevada foothills by California buckeye (Aesculus californica).

Mountain maple (Acer glabrum var. torreyi)

As with mountain ash, I found a single small tree representing this species near the west shore of Emerald Bay while hiking the Rubicon Trail.  Despite lacking foliage, I recognized it immediately as a maple by its opposite, scaly buds.  Also like mountain ash, I assumed I would see more after finding the first one and thus didn’t photograph this particular tree growing in deep shade.  That’ll teach me.  This species sometimes grows as a multi-stemmed shrub in moist situations, and even when assuming tree form, as did the one I saw, it is at best a small tree with a maximum height of only around 15′.  With fall foliage in varying shades of pink to red, it must rather nicely compliment the blazing yellow cloak of the quaking aspen during September and October.  Tahoe Basin individuals are placed in var. torreyi due to their bright reddish twigs, while those on the eastern slope of the Sierra Nevada exhibit gray twigs and are placed in var. diffusum.

This concludes my “Trees of Lake Tahoe” series – at least until next year when I hope to locate some of the remaining species I did not find during this year’s visit.  However, I do have one more “flora of Lake Tahoe” post in preparation covering some of the many woody shrubs that occur within the basin.

REFERENCES:

Arno, S. F. 1973. Discovering Sierra Trees. Yosemite Association, Yosemite National Park, California, 89 pp.

Graf, M. 1999. Plants of the Tahoe Basin. Flowering Plants, Trees, and Ferns. A Photographic Guide. California Native Plant Society Press, Berkeley, 308 pp.

Muir, J. 1894. The Mountains of California. The Century Co., New York, xiii+381 pp.

Muir, J.  1918. Steep Trails. Houghton, Mifflin, Boston, ix+390 pp.

Nixon, K. C. 2002. The oak (Quercus) biodiversity of California and adjacent regions. USDA Forest Service General Technical Report PSW-GTR-184, 20 pp.

Peterson, P. V., and P. V. Peterson, Jr. 1975. Native Trees of the Sierra Nevada. University of California Press, Berkeley, 147 pp.

Quinn, C.  2006.  A Nature Guide to the Southwest Tahoe Basin: Including Desolation Wilderness and Fallen Leaf Lake: Trees, Shrubs, Ferns, Flowers, Birds, Amphibians, Reptiles, Mammals, and Fishes Inhabiting the Sierra Nevada Watershed Southwest of Lake Tahoe, California.  CraneDance Publications, Eugene, Oregon, 232 pp. 

Copyright © Ted C. MacRae 2009

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Sanctuary for the Betulaceae

Nestled on the eastern side of the St. Francois Mountains, where the craggy exposures of the Ozarks most ancient rocks begin to subside underneath the Cambrian sandstones laid down over them, lies Hawn State Park – considered by many to be the loveliest of Missouri’s state parks. I have written previously about Hawn – in fact, it was the subject of my very first post on this blog. I have long treasured Hawn for its excellent insect collecting, diversity of plants and habitats, and unbridled beauty. I have hiked the incomparable Pickle Creek and Whispering Pine Trails many times – far more than any other trail in the state, and each time I fall more deeply in love with what, to me, represents the essence of the Missouri Ozarks in their most pristine state.

Lamotte sandstone cutThe charm of Hawn results from a unique combination of geological features. The Lamotte sandstone outcrops that dominate Hawn’s landscape are the oldest sedimentary rocks in the state, formed from coarse sand deposits that were laid down over the Precambrian rhyolites and granites that form the core of the St. Francois Mountains. These sand deposits were themselves buried under limestone and dolomite layers formed at the bottom of vast seas that later covered much of the interior of the continent. Subsequent periods of uplift and erosion once again exposed these sandstones, whose unique ability to hold groundwater has resulted in the formation of spring-fed streams that have cut deep into their soft layers to create canyon-rimmed valleys with tall vertical cliffs. rhyolite shut-ins One of these streams is Pickle Creek, which is fed throughout the year by Pickle Spring and has in some places cut all the way down to the underlying igneous rock to form “shut-ins.” In contrast to the slow, sandy bottomed stretches where Pickle Creek is still cutting through sandstones, the water in these igneous shut-ins rushes through narrow openings in the highly resistant rock. The igneous and sandstone exposures found in Hawn are spectacularly beautiful and support a unique flora due to the acid soils they produce. One group of plants that have taken sanctuary in these moist, acid soils is the Betulaceae, or birch family. Missouri is home to five native species of Betulaceae¹, and while none of them are extraordinarily uncommon they are limited in their occurrence to natural communities with sufficient moisture and exhibit a clear preference for acidic soils. This confluence of conditions occurs perfectly along Pickle Creek, allowing all five native species to grow here side-by-side – a betulaceous “hot spot” that represents not only the full diversity of the family in Missouri, but also the total generic diversity of the family in North America. In fact, only one other genus (Ostryopsis, shrubs related to Corylus and restricted to China) is assigned to the family on a global basis (Furlow 2004).

¹ Dr. George Yatskievych, in his recently published Steyermark’s Flora of Missouri (2006), regarded the presence of Corylus cornuta in Missouri as unlikely despite earlier reports of such. Dr. Yatskievych also recorded a single escape of the European species Alnus glutinosa from Springfield, Missouri.

The Betulaceae are deciduous trees and shrubs that occur primarily in the boreal and cool temperate zones of the Northern Hemisphere, although outposts are also known from high elevations in the Neotropics and, as mentioned above, China. Fossils of this ancient lineage of flowering plants are traceable to the late Mesozoic (upper Cretaceous), and the family appears to form a clade with hamamelidaceous plants. As would be expected from a group with boreal affinities, most species exhibit adaptations for survival in cold climates, such as small stature, shrubby growth habits, and small leaves. Several of Missouri’s species have performed well and gained acceptance as ornamental trees and shrubs, while others are important as sources of hazelnuts (genus Corylus) or ecologically for their ability to fix nitrogen (genus Alnus). My interest in these plants has nothing to do with their economic importance, but rather in their role as host plants for several rarely encountered species of woodboring beetles. Often, insects in this group may be collected on foliage of their hosts during the summer, making host identification fairly easy due to the presence of leaves. This is not always possible, however, due to limited periods of adult activity or low population densities. Rearing these insects from their hosts provides additional opportunity to document their occurrence, and winter is often the best time to collect the dead branches in which they breed, since by that time they have nearly completed their development and will be ready to emerge as soon as temperatures rise during spring. Identifying woody plants without foliage can be a challenge, but the ability to distinguish host plants by non-foliage characters such as bark, growth habit, bud shape, etc. greatly facilitates studies of wood boring beetles through rearing. In the past I have relied heavily on Cliburn and Klomps’ (1980), A Key to Missouri Trees in Winter, which utilizes mostly details of the twigs and buds to discriminate among Missouri’s 160+ species of trees. However, after a certain level of familiarity is gained, one eventually learns to recognize winter trees and even downed logs or fallen branches simply by their “look”.

Betula nigra - habit

Betula nigra - habit

Betula nigra - old bark

Betula nigra - old bark

Betula nigra - sapling

Betula nigra - sapling

Betula nigra (river birch) is the only member of this largely boreal genus found in the middle and southern latitudes of the U.S. and, thus, cannot be confused with any of Missouri’s other betulaceous species². It is the largest of the five and, along with the following species, is the most demanding in terms of keeping its “feet” wet. Trees are usually encountered right at the water’s edge, with tall, slender, often twisted or leaning trunks. Young trees and large branches on older trees exhibit gorgeous reddish brown bark peeling in thin, papery sheets, becoming thick and scaly on the main trunks of older trees. Small branches are dark, purplish brown in color with smooth bark and distinctly horizontal lenticels.  I have reared a small jewel beetle from fallen, dead branches of this tree collected at several locations in Missouri – this beetle turned out to be new to science, which I described and named Agrilus betulanigrae in reference to its (then) only known host (MacRae 2003).  I have also reared tremendous series of another jewel beetle, Anthaxia cyanella, which at the time was not known to utilize this host and was considered uncommon.  As it turns out, Betula nigra is its preferred host, and the rearing of large series from many locations resulted in improved knowledge about color forms and variability in this species (MacRae & Nelson 2003).

² The widely planted but dreadfully non-adapted Betula pendula (European white birch) and B. papyrifera (paper birch) can be recognized by their distinctly white bark. These species are limited to urban landscapes where they rarely achieve significant stature before declining and eventually succumbing to insect pests such as Agrilus anxius (bronze birch borer). River birch provides an equally attractive and much more durable choice!

Alnus serrulata - habit

Alnus serrulata - habit

Alnus serrulata - sapling

Alnus serrulata - sapling

Alnus serrulata - old cones

Alnus serrulata - old cones

Alnus serrulata (common alder, hazel alder, smooth alder, tag alder…) also demands to be next to (or even in) the water.  Unlike B. nigra, however, this species rarely reaches true tree status, instead usually forming shrubby thickets along the water’s edge.  Saplings can resemble those of B. nigra due to their smooth brownish bark, but the latter is usually more purplish, and the lenticels of A. serrulata are not distinctly horizontal as in B. nigra. The large purple-red buds also differ from the small brown buds of B. nigra, and during winter A. serrulata is adorned with numerous staminate catkins.  The persistent woody cones also cannot be mistaken for those of any other species of Betulaceae in Missouri. Associated with this plant is the longhorned beetle, Saperda obliqua, which reaches its southwesternmost distributional limit in Missouri on the basis of a single specimen collected some 25 years ago right here along Pickle Creek and given to me by lepidopterist George Balogh. Numerous attempts to find this species here since then have not (yet!) been successful.

Carpinus caroliniana - habit

Carpinus caroliniana - habit

Carpinus caroliniana (blue beech, hornbeam, musclewood) is one of my favorite betulaceous species. The beautifully fluted trunks and smooth, light gray bark are remniscent of the limbs of a sinewy, muscular person – every time I see this tree I cannot resist the temptation to grab and stroke the hard limbs (should I be admitting this?). This character begins to show even in very young trees, making its identification during winter quite easy. These trees also like to be near water, but they are not so demanding to be right at the water’s edge as are the previous two species. They usually form small trees, often in clumps with multiple trunks.  There are some notable insect associations that I’ve found with this plant.  One is a small jewel beetle, Agrilus ohioensis, which I reared from dead branches of this plant collected along Pickle Creek (Nelson & MacRae 1990), and which after more than 20 years still remain the only known Missouri specimens of this species.  Another is the longhorned beetle, Trachysida mutabilis, a single adult of which I reared from a dead (almost rotting) branch of this plant collected not too far from Pickle Creek in Iron Co.  This beetle also is the only representative of its species known from Missouri (MacRae & Rice 2007).

Ostrya virginiana - habit

Ostrya virginiana - habit

Ostrya virginiana - trunk

Ostrya virginiana - trunk

Ostrya virginiana (hop hornbean, American hornbeam) has a form and growth habit very similar to C. caroliniana, but its leaves that persist through the winter make it instantly recognizable from afar.  In Missouri, this habit is most often seen with the oaks (Quercus spp.).  This species can be found even further away from the water than the previous species, and its small stature combines with the orangish, persistent leaves to form a distinctive understory layer during winter.  Also, in contrast to the smooth gray bark of Carpinus, this species exhibits scaly, light reddish brown to brownish gray bark.  I have succeeded in rearing one of the two known Missouri specimens of another jewel beetle, Agrilus champlaini, from O. virginiana collected along Pickle Creek (the other specimen was reared from wood collected at Graham Cave State Park, another site where sandstone bedrocks favor an O. virginiana understory).  Unlike most other jewel beetles, A. champlaini forms galls in small living branches of its host.  I have collected the distinctive swellings during winter on many occasions but managed to rear only these two individuals (plus one ichneumonid parasitoid).  I have also noted similar swellings on Carpinus but have not yet managed to definitely associated them with this beetle.

Corylus americana (hazelnut, American hazelnut) is the smallest of Missouri’s five betulaceous species, always forming shrubs, sometimes in thickets, and never assuming the form of a tree. Its staminate catkins present during winter immediately identify plants of this species as Betulaceae, but the small, globe-shaped buds are unlike the more pointed buds of Ostrya and the elongated, reddish buds of Alnus. This species is the least demanding in terms of being near water and can be found even in upland prairies and glades. I haven’t yet associated any woodboring beetles with this plant in Missouri, but there are several jewel beetles known from the eastern U.S. that utilize Corylus (Agrilus corylicola, A. fulgens, and A. pseudocoryli) and could occur in Missouri.

pine savanna - fire managementThe upland habitats at Hawn are of interest as well. Lamotte sandstones are the dominant bedrock, creating acid soils that support a canopy dominated by Missouri’s only native species of pine, Pinus echinata (shortleaf pine), several species of oak, and a diversity of acid-loving shrubs primarily in the family Ericaceae (including the stunningly beautiful Rhododendron prinophyllum, or wild azalea). Historically, so-called “pine savanna” was prevalent in this area, a natural community in which periodic fires maintained an open structure amongst the fire-adapted pines and allowed a diverse herbaceous layer beneath the open canopy. Much of Hawn has closed up after decades of fire suppression; trail through pine savannahowever, the Department of Natural Resources has implemented a rotational burn management regime to recreate pine savanna habitat within Hawn’s Whispering Pines Wild Area. Evidence of what appeared to be very recent burns could be seen at several places as I hiked along the Whispering Pines Trail, and while many visitors might have been alarmed at the apparent “damage” they were observing, my heart sang with the prospect of seeing mature pine savanna communities taking hold throughout my beloved Hawn. As I stood atop this ridge and looked back down from where I had come, I could almost see Henry Schoolcraft and Levi Pettibone in the distance on horseback, perhaps pausing to gaze at an elk.

REFERENCES:

Cliburn, J. and G. Klomps. 1980. A Key to Missouri Trees in Winter, 2nd edition. Missouri Department of Conservation, Jefferson City, 43 pp. (subsequently revised)

Furlow, J. J.  2004. Betulaceae in Flora of North America @ efloras.org. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=10101.

MacRae, T. C. 2003. Agrilus (s. str.) betulanigrae MacRae (Coleoptera: Buprestidae: Agrilini), a new species from North America, with comments on subgeneric placement and a key to the otiosus species-group in North America. Zootaxa 380:1–9.

MacRae, T. C., and G. H. Nelson. 2003. Distributional and biological notes on Buprestidae (Coleoptera) in North and Central America and the West Indies, with validation of one species. The Coleopterists Bulletin 57(1):57–70.

MacRae, T. C. and M. E. Rice. 2007. Distributional and biological observations on North American Cerambycidae (Coleoptera). The Coleopterists Bulletin 61(2):227–263.

Nelson, G. H. and T. C. MacRae. 1990. Additional notes on the biology and distribution of Buprestidae (Coleoptera) in North America, III. The Coleopterists Bulletin 44(3):349–354.

Yatskievych, G. 2006. Steyermark’s Flora of Missouri, Volume 2. The Missouri Botanical Garden Press, St. Louis, 1181 pp.

Copyright © Ted C. MacRae 2009

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