pollination

2019 WGNSS Nature Photo Contest

/ Ted C. MacRae / 4 Comments

Last night the Webster Groves Nature Study Society (WGNSS) held their 2019 Nature Photo Contest, and I was fortunate to have a 1st place winner in the ‘Plants and Fungi’ category! This photograph of grassleaved lady’s tresses orchid (Spiranthes vernalis) flowers was taken at Taberville Prairie Natural Area in St. Clair Co., Missouri. Like other species of lady’s tresses orchids, their tubular flowers are arranged in a spiral along the inflorescence and cross-pollinated primarily by long-tongued bees (e.g. bumblebees, Bombus spp., and megachilid bees) (van der Cingel 2001).

Spiranthes vernalis (spring lady's tresses)

Grassleaved lady’s tresses orchid (Spiranthes vernalis), Taberville Prairie Natural Area, St. Clair Co., Missouri.

Spiranthes is one of the more complex genera of North American orchids, with seven species known to occur in Missouri (Summers 1985), and like almost all orchids, their pollination biology is fascinating! The flowers are “protandrous”, i.e., they are functionally male when they first open and become functionally female as they age. Since they open sequentially from the base of the inflorescence as it grows, this results in female flowers on the lower portion of the inflorescence and male flowers on the upper portion.  Thus, bee pollinators tend to act as pollen donors when visiting lower flowers and pollen recipients when visiting upper flowers.  Male pollinia are attached to the bee’s proboscis as it tries to access the nectar secreted into the base of the floral tube and then come in contact with the female stigma in the next flower that the bee visits.  Bees generally start at the bottom of an inflorescence when visiting a plant and then spiral up to the top before flying to the next plant.  Such “acropetal movement” is likely a result of the tendency for nectar rewards to be greater in the lower flowers, and it ultimately promotes cross-fertilization between neighboring plants.

This was the 4th edition of the contest, which has been held every other year since the inaugural edition in 2013. I’ve earned 2nd and 3rd place honors in the plants category each time before; however, this was my first win in that category. In addition to plants, I also had entries in the ‘Invertebrates’ (restricted to photos taken in Missouri or one of its contiguous states) and ‘Travel’ (open to photos taken anywhere in the world) categories, with one photo each making it to the final round of judging. You’ve seen them both before—Neotibicen superbus (below left—photographed at Mincy Conservation Area, Taney Co., Missouri) and Agrilus walsinghami (below right—photographed at Davis Creek Park, Washoe Co., Nevada). In the end, however, they both got beat out by the competition, so I only had the one winning photograph this time. Nevertheless, it was a 1st place winner, so I am very satisfied.

Neotibicen superbus

The WGNSS Nature Photo Contest has quickly become one of the organization’s marquee events, with the number of entries, caliber of competition, and attendance all exceeding the previous three editions. My thanks to the judges who volunteered their time, the attendees who supported the event, and especially to Bill Duncan, Chair of WGNSS’s Nature Photography Group (and an expert nature photographer in his own right), who worked hard to make this event the success that it was (and took home some well-deserved wins of his own). I look forward to the next competition in 2021!

REFERENCES:

Summers, B.  1981.  Missouri Orchids.  Missouri Department of Conservation, Natural History Series No. 1, 92 pp.

van der Cingel, N. A.  2001.  An Atlas of Orchid Pollination: America, Africa, Asia and Australia. A. A. Balkema, Rotterdam, Netherlands, 296 pp.

© Ted C. MacRae 2019

Pedantic Sunday: Blister beetles don’t suck

/ Ted C. MacRae / 5 Comments
Nemognatha cribraria cribraria on flower head Chrysothamnus viscidiflorus | Millard Co., Utah

Nemognatha cribraria cribraria on flowers of Chrysothamnus viscidiflorus | Millard Co., Utah

The beetle featured in today’s photo is the blister beetle (family Meloidae), Nemognatha cribraria cribraria. The genus Nemognatha and its relatives in the subfamily Nemognathinae are distinctive due to the greatly elongated adult mouthparts that are modified for feeding on flowers. Specifically, parts of the maxillae, or second pair of mouthparts (behind the mandibles) are elongated to allow access to nectar in flowers with deep corollas, while the fairly standard-issue chewing mandibles are used for feeding on pollen. As pointed out by Enns (1956) in his revision of the North American members of the genus, the length of the maxillae seems to be related to the particular kind of flower preferred for feeding by the various nemognathine species, with species exhibiting longer maxillae adapted to feeding on flowers with deeper corollas. In the photo above, the elongated maxillae can be seen tucked underneath the adult and appear to be nearly half the length of the body—other species in the genus have the maxillae as long as the body, or in the case of a Mexican species (N. chrysomeloides) even longer than the body (Enns 1956).

The proboscis-like mouthparts of nemognathine blister beetles are often depicted in entomological texts as an amazing example of sucking mouthparts in Coleoptera, the vast majority of which possess strictly chewing mouthparts. Borrer et al. 1976, White 1983, Downie & Arnett 1996, and Pinto & Bologna 2002 all mention that the mouthparts are modified into an elongated proboscis for “sucking” nectar, and it has been suggested that nectar uptake occurs through a median food canal, formed by concavities on the inner surfaces when the two structures are locked together into a functional unit. However, Wilhemi & Krenn (2012) used scanning electron microscopy and micro computerized tomography to study the elongated mouthparts of three meloid genera: Nemognatha and Gnathium and Leptopalpus. They demonstrated that neither the elongated galeae of Nemognatha and Gnathium nor the elongated maxillary palpi of Leptopalpus formed a median food canal through which nectar is sucked. Furthermore, the filiform galeae of Nemognatha and Gnathium are densely covered with long bristles, suggesting that nectar uptake in these two genera is accomplished by capillary action along the bristles of the proboscis. In all three genera nectar transport is likely aided by musculature around the mouth.

REFERENCES:

Borrer, D. J., D. M. DeLong & C. A. Triplehorn. 1976. An Introduction to the Study of Insects, Fourth Edition. Holt, Rinehart and Winston, xii + 852 pp.

Downie, N. M. & R. H. Arnett, Jr. (Eds.). 1996. The Beetles of Northeastern North America. Volume II: Polyphaga: Series Bostrichiformia through Curculionoidea. The Sandhill Crane Press, Gainesville, Florida, x + 891–1721.

Enns, W. R. 1956. A revision of the genera Nemognatha, Zonitis, and Pseudozonitis (Coleoptera, Meloidae) in America north of Mexico, with a proposed new genus. The University of Kansas Science Bulletin 37, part 2(17):685–909 [Biodiversity Heritage Library].

Pinto, J. D. & M. A. Bologna. 2002. Chapter 111. Meloidae Gyllenhal 1810, pp. 522–529. In: R. H. Arnett, Jr., et al. (Eds.). American Beetles, Volume 2. CRC Press, Gainesville, xiv + 861 pp.

White, R. E. 1983. A Field Guide to the Beetles of North America. The Peterson Field Guide Series, Houghton Mifflin Co., Boston, xii + 368 pp.

Wilhelmi, A. P. & H. W. Krenn. 2012. Elongated mouthparts of nectar-feeding Meloidae (Coleoptera). Zoomorphology [abstract].

Copyright © Ted C. MacRae 2013

Friday Flower – Hedychium coccineum

/ Ted C. MacRae / 6 Comments

Distrito Joaquim Igidio is one of four “districts” surrounding Campinas, Brazil.  It is the most remote of the four, with farmsteads dating back more than a century interspersed amongst some of the most significant tracts of Atlantic forest still remaining in the area.  Many of the farmsteads have recently been converted to bars and restaurants featuring live music, making the area a popular weekend getaway for Campineros.  I joined my colleague and some of his friends on a visit to one of these—Bar do Cachoeira—over the weekend during my visit this past January.  After a sumputuous lunch of Brazilian cuisine (including tohesmo torresmo—my new favorite dish) and cerveja, I walked the grounds to look for insects to photograph.  Despite only having an hour or so to look around, the two species of treehoppers I found and photographed made it a successful little venture.  Coming back to rejoin my friends, I saw a few plants with these marvelously bizarre inflorescenses growing alongside a forested stream running through the grounds.  I could tell they were some type of monocot, but beyond that I had no idea.  Something inside me suspected, however, that this was likely not a native species—it just had that introduced, tropical ornamental look to it.  My suspicions were confirmed when I showed the photos to Dr. George Yatskievych, Curator at the Missouri Botanical Garden and Director of the Flora of Missouri Project.  George identified the plant as Hedychium in the Zingiberaceae (ginger family), likely one of the cultivars of Hedychium coccineum.  He added:

This species is native to tropical Asia, but is commonly cultivated in warm regions of the world. A number of cultivars and hybrids involving related species are sold, so it’s hard to be sure which one you photographed.  The most common cultivar seems to be cv. ‘Tara’ and that’s a possibility for your plant.

Known by a number of common names (red gingerlilly, orange gingerlily, scarlet gingerlily, orange bottlebrush ginger, etc.), H. coccineum hails from the eastern Himalyas, where it grows along forest edges and in mountain grasslands.  This herbaceous perennial can reach one to two metres in height and, in some places, has become somewhat invasive.  The existence of rhizomes and bulbs can make control particularly difficult.

An interesting feature of the plant is the long, exserted stamens and stigmas of the flowers.  This feature is suggestive of an interesting pollination mechanism that relies on pollen attachment to the wings rather than the main body of its moth and butterfly pollinators. Pollen transfer is effected as the lepidopterans move from flower to flower seeking nectar, brushing their wings against the floral parts in the process and thus pollinating the flowers (Zomlefer 1994).

REFERENCE:

Zomlefer, W. B. 1994. Guide to flowering plant families. University of North Carolina Press, Chapel Hill, 430 pp.

Copyright © Ted C. MacRae 2011

Friday Flower – Ceibo

/ Ted C. MacRae / 8 Comments

Erythrina crista-galli (''ceibo'') | Buenos Aires, Argentina

One of the major flowering spectacles in Argentina is Erythrina crista-galli, or “ceibo” (also spelled “seíbo”).  So great is this spectacle that both Argentina and Uruguay have declared it their national flower.  I’ve seen only hints of it myself, as all of my trips to Argentina have been either before the peak bloom period from November to February or just after.  These blossoms were seen during my most recent trip last month in Buenos Aires at La Reserva Ecológica Costanera Sur, where for most of the day I saw only the occasional, single, straggling blossom before finally encountering the delightful trio near the end of the day.  The elegant simplicity of this photo contrasts starkly with the riotous quality that photographs of this tree in full bloom have (it may be one of the most photographed flowers on the web!).

Native also to Uruguay, Paraguay and Brazil, E. crista-galli has also been planted widely in warmer regions of the world (where it is generally known as cockspur coral tree or cry-baby tree).  Not everyone, however, is so enamored with this tree. In New South Wales, Australia, E. crista-galli has become abundant along several watercourses and is regarded locally as a significant invasive weed (Smith 1996). As in its native South America, its seeds are dispersed by floodwaters and germinate progressively over a period of three years, forming thickets (called “seibales” in Argentina) that can displace native vegetation.

The flaming red color of the flowers would suggest hummingbirds are the primary pollinators, and species in the genus Erythrina are generally characterized as hummingbird/passerine pollinated (Galetto 2000).  However, the broad, undulating “explanade” formed by the lower lip apparently serves as a landing platform for bee pollinators (Haene and Aparicio 2007).  Galetto et al. (2000) note that E. crista-galli is placed basally within the genus and suggest that it may represent an intermediate step in the shift from insect pollination to the bird pollination more typical within the genus. 

REFERENCE:

Galetto, L., G. Bernardello, I. C. Isele, J. Vesprini, G. Speroni and A. Berduc.  2000.  Reproductive biology of Erythrina crista-galli (Fabaceae).  Annals of the Missouri Botanical Garden 87(2):127–145.

Haene, E. and G. Aparicio.  2007.  100 Trees of Argentina. Editorial Albatros, Buenos Aires, República Argentina, 128 pp. [una foto de las floras de E. crista-galli aparece en la portada de este libro, un regalo que me dio mi colega y buen amigo, Guillermo Videla – muchas grácias!]

Smith, J. M. B.  1996.  Notes on Coral-Trees (Erythrina) in Australia with particular reference to E. crista-galli L. in New South Wales.  Australian Geographical Studies 34(2):225–236.

Copyright © Ted C. MacRae 2011

Trichodes bibalteatus in Oklahoma

/ Ted C. MacRae / 6 Comments

Among checkered beetles (family Cleridae), the genus Trichodes contains among the largest and most strikingly-colored species.  The 11 North American species of this predominantly Holarctic genus are primarily western in distribution, although two species (T. nuttalli and T. apivorus) do occur in the eastern U.S.  The individual in these photos was one of several I encountered feeding on the flowers of a yellow composite in the Gloss Mountains of northwestern Oklahoma during early July.  I take them to represent the species T. bibalteatus based on their close resemblance to the holotype of that species from the LeConte Collection in the Museum of Comparative Zoology at Harvard University.  While these photographs are admittedly far from perfect, they were about the best I could manage at the time considering the gusty post-storm winds that I encountered atop the mesa where these beetles were found (along with my continuing difficulty in achieving proper exposure with subjects on bright yellow flowers).

The striking colors of adult Trichodes and their frequent association with flowers for feeding and mating belies a more treacherous aspect of their life history.  While adults may serve as important pollinators of native plant species (Mawdsley 2004), they also lay their eggs on flowers.  The larvae that hatch from these eggs don’t eat the flower itself, but rather attach themselves to bees and wasps that visit the flower as they gather pollen for provisioning their own nests (Linsley & MacSwain 1943).  The larvae hitch a ride back to the hymenopteran’s nest, where they then prey on the developing brood and usurp pollen provisions for themselves.

Photo Details: Canon 50D w/ MP-E 65mm 1-5X macro lens (ISO 100, 1/250 sec, f/16), Canon MT-24EX flash (1/8 ratio) w/ Sto-Fen + GFPuffer diffusers. Typical post-processing (levels, minor cropping, unsharp mask).

REFERENCE:

Linsley, E. G. & J. W. MacSwain. 1943. Observations on the life history of Trichodes ornatus (Coleoptera, Cleridae), a larval predator in the nests of bees and wasps. Annals of the Entomological Society of America 36:589–601.

Mawdsley, J. R. 2004. Pollen transport by North American Trichodes Herbst (Coleoptera: Cleridae). Proceedings of the Entomological Society of Washington 106(1):199-201.

Copyright © Ted C. MacRae 2010

Friday Flower – Dwarf Spiderwort

/ Ted C. MacRae / 21 Comments

Living at the foothills of the Ozark Highlands, I sometimes forget how unique the biota of this ancient landscape truly is. More than 200 species of plants and animals are largely restricted to the region, with around 160 of these being true Ozark endemics found nowhere else on earth. The biodiversity of the region stems from the landform’s unusual geology, topography and hydrology, it’s ectotonal position within the North American continent, and its distinction as the only significantly elevated landform between the Appalachian and Rocky Mountains. Many Ozark endemics are found in the region’s abundant caves and sinkholes, formed by underground dissolution of its massive limestone/dolomite bedrocks. Others represent isolated populations of more typically northern plants and animals that found refuge here during the Pleistocene glacial advances. Still others evolved during periods of isolation when vast inland seas covered much of the continent’s interior.

Tradescantia longipes, known locally as dwarf spiderwort or wild crocus, is a particularly exquisite Ozark endemic found scattered in dry igneous woodlands of the Missouri’s St. Francois Mountains and Arkansas’ Ouachita Mountains. I first saw this species two years ago in May at Crane Lake in the heart of the St. Francois Mountains, and the plants shown here were seen this past April in the igneous woodlands of Sam Baker State Park at the southernmost extent of the St. Francois Mountains’ igneous exposures. The genus to which this plant belongs contains some much more widely distributed (though no less striking) members (e.g. T. ohioensis, which I featured in my first “Friday Flower” post). Tradescantia longipes flowers are similar to those of T. ohioensis, but the plant differs from most others in the genus by its short, squat habit of growth and strictly basal leaves.

One feature shared by T. longipes with all other members of the genus is the dense fringe of hairs arising from the stamen filaments.  I discussed these in my first Friday Flower post, noting that each of the 70-100 hairs per filament is composed of a chain of about 20 large, single cells – easily seen with low magnification. While their sensitivity to radiation and chemical mutagens has been recognized for many years (the hairs turn pink when exposed to radiation), less seems to be known about their natural function for the plant.  It is interesting to note, however, that the flowers of Tradescantia and related genera rely heavily on insects for pollination (primarily bees and bee flies), yet they do not produce nectar.  Faden (1992) has speculated that the stamen hairs might combine with floral scents and the nearly pollenless anthers to deceptively attract insects, provide footholds, retain pollen fall, and influence the pollen-collecting behavior of the insects.

Photo Details: Canon 50D (ISO 100, 1/250 sec, f/14-18), Canon 100mm macro lens, Canon MT-24EX flash (1/4 ratio) w/ Sto-Fen diffusers. Post-processing: levels, unsharp mask, minimal cropping.

REFERENCE:

Faden, R. B.  1992. Floral attraction and floral hairs in the Commelinaceae.  Annals of the Missouri Botanical Garden 79(1):46–52.

Copyright © Ted C. MacRae

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Friday flower – Krameria lanceolata

/ Ted C. MacRae / 11 Comments
Photo details: Canon 100mm macro lens on Canon EOS 50D, ISO 100, 1/250 sec, f/9, MT-24EX flash 1/4 power w/ diffuser caps.

Photo details: Canon 100mm macro lens on Canon EOS 50D, ISO 100, 1/250 sec, f/9, MT-24EX flash 1/4 power w/ diffuser caps.

I encountered few insects this past June on the dry slopes of sand shinnery oak shrubland that just makes it into the northwestern corner of Oklahoma’s Four Canyon Preserve – insect population levels were still depressed from the wildfire that swept through the area in April of last year.  Plant life, however, was diverse and abundant, including this most unusual plant – Krameria lanceolata (many common names, including trailing krameria, trailing ratany [sometimes spelled “rhatany”], Texan ratany, prairie sandbur, sandspur, etc.).  A dicot in the monogeneric family Krameraceae, plants in this genus share several unusual traits, the most obvious being their distinctly orchid-like, zygomorphic flowers (i.e., capable of division into symmetrical halves by only one longitudinal plane passing through the axis).  The resemblance to orchids is strictly superficial – they are most closely related to plants in the family Zygophyllaceae.

Orchids, of course, are monocots with trimerous flowers that only appear to be five-petaled because of the three petal-like sepals and the third true petal being modified into a “lip” onto which pollinating bees land.  Krameria flowers also appear five-petaled with a lip, but in this case it is the five sepals that form the “petals,” while the five true petals are modified into a lip (three fused petals) and two lateral upright “flags” called elaiphores.  These eliaphores play a central role in Krameria‘s unusual pollination biology, whose flowers produce not nectar, but fatty oils as rewards for their visitors – female bees of the genus Centris (Anthophoridae) (Simpson and Neff 1977).  The bees collect the oils from the modified external surfaces of the eliaphores, pollinating the flower in the process, and mix the oils with pollen to feed their larvae.  Although the Krameria plants are wholly dependent upon Centris bees to effect their pollination, the relationship is not mutually exclusive – Centris bees utilize other oil-producing plants as well.

All species of Krameria examined to date are obligate semiparasites, forming haustoria on the roots of a broad range of host plants.  Of the 18 species currently known in the genus, five occur in the U.S., with K. lanceolata the most widespread (Kansas and Colorado south to Arizona, New Mexico, and Texas and east to Georgia and Florida) (Austin and Honeychurch 2004). It is distinguished from the other U.S. species by its herbaceous, prostrate form.

Update 8/10/09: Mike Arduser, my hymenopterist friend who visited Four Canyon Preserve with me, wrote the following in response to my query about collecting bees from these flowers:

Yes, collected several off Krameria at Four Canyons and at Packsaddle – all were the same species, and I’m trying to remember the name as I’m writing this (all notes and material are at home) –  it was Centris lanosa. They are best found by listening, as they have a distinctive buzz as they move from flower to flower at ground level (difficult to see there).

REFERENCES:

Austin, D. F. and P. N. Honychurch.  2004.  Florida ethnobotany. CRC Press, Boca Raton, Florida. 909 pp.

Simpson, B. B. and J. L. Neff. 1977. Krameria, free-fatty acids and oil-collecting bees. Nature 267: 150-151.

Copyright © Ted C. MacRae

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