Bumblebee buzz-pollinating Wild Senna

 

Bee sure to turn your volume up!

A short video of bumblebees buzz-pollinating my Wild Senna (Senna hebecarpa) this morning. Buzz pollination, or sonification, is essential for the extraction of pollen in certain groups of plants, including some pea family members like the senna, blueberries, potatoes and tomatoes. In buzz pollinated plants, the pollen is held tightly in specially shaped anthers. Slits in the anther are not large enough for pollen-seeking insects to access and thus access the reward within. However, vibration at a certain frequency releases the pollen through those same pores. The bumblebee takes some of the nutrient-rich pollen to eat. Other harvested pollen is made into a rich paste to feed the larvae within their nests. Along the way, the uber-fuzzy insects deposit pollen on the reproductive parts of other senna plants. Worthington, Ohio.

Of Bees and Bugloss

The golden glow of a recent early morning sunrise illuminates the stark barrens of Oakes Quarry Preserve in northeastern Greene County, Ohio. This site is the northernmost holding of the conservation tour de force known as the Beaver Creek Wetlands Association.

I've had opportunity to make brief visits to the site three times this summer, all for different objectives. The quarry was originally opened in the 1920's, and covers about 190 acres. In making lemonade from limestone, Nature has populated the aged quarry with lots of interesting things, not the least of which are birds. While the habitat above may look non-diverse, its surprising how many birds occupy the site. Prairie Warbler, Green Heron, Spotted Sandpiper, Field Sparrow, Belted Kingfisher, Killdeer, Eastern Towhee, and of course the quarry's most famous residents, Lark Sparrows.

As I explored the quarry's open floor, the plant life naturally caught my eye. There are some tough natives colonizing the sun-drenched arids, such as these Black-eyed Susans, Rudbeckia hirta. But what was of most interest to me were some unusual "weeds".

The strange little Bracted Plantain, Plantago aristata, grows in profusion in the rocky barrens. This is a TOUGH little plant. A native of the western U.S. and adjacent Canada, it is indigenous as far east as Illinois. In modern times, abetted by large-scale disturbance, it has spread eastward throughout Ohio and beyond.

I don't see Bracted Plantain very often, but it is easy to overlook. Plants often stand only a few inches tall, and it often grows in xeric waste zones, such as gravelly road verges, that few of us frequent. Upon close inspection, the plant does have its charms, and I took the opportunity to add it to my photographic bucket list.

Far more conspicuous than the Bracted Plantain was this can't-miss weed, the Viper's Bugloss, Echium vulgare. This is another one that I seldom see, perhaps again because I do not frequent railroad ballast and other very dry highly unnatural sites favored by this species.

Viper's Bugloss is indigenous to Eurasia, and is sometimes also known by the colorful names of Blue Devil or Blueweed. The "viper" part of the typically used name comes from the shape of the bony nutlets (fruit), which are said to resemble a serpent's head.

The curious word "bugloss" comes from old Greek and means "ox-tongued". It probably alludes to the long pinkish stamens that are conspicuously exert from the flower corolla.

As I rarely see this weed, I took full opportunity to create images of the ultra-showy flowers on my last trip to Oakes Quarry. The onset of a brief summer rainstorm wetted the plants, creating an even showier look.

I've long been fascinated with "weeds". While the definition of weed is not hard and fast, it might be summed as "a weed is in the eye of the beholder". To me, the definition should be a bit more exacting than that. A weed is a plant originally not native to the area in which it now occurs (using European settlement as the benchmark for this part of the world).

Weeds can be placed in two broad categories: the innocuous curiosities, and the invasive scourges. Kudzu, bush honeysuckles, Purple Loosestrife, and Garlic Mustard clearly fit the latter category. But the vast majority of weeds are not particularly invasive, don't overrun native plant communities, and often only flourish in heavily altered habitats, such as this quarry. The Viper's Bugloss is a good example of an innocuous curiosity, at least insofar as I am aware.

It didn't take long to realize that, nonnative weed or not, the native bumblebees were smitten with the bugloss flowers. Here, a bumblebee sleeps off yesterday's nectar binge next to some flowers. Efficient pollinators in the extreme, bumblebees typically sleep on or next to the flowers that they hunt for nectar. Once the morning sun warms them enough, they shake awake and immediately plunge back into the nectar troughs.

NOTE: "Bumblebee" is often written as two separate words: "Bumble bee". However, given the widespread awareness of these insects and the frequent usage of the name in either aforementioned form, I think it is better to adopt the compound word "bumblebee." These valuable insects warrant their own compound name, and such treatment keeps with a growing trend towards commonsense adoption of compound words.

A bumblebee is caught in action, dropping onto a bugloss flower. This particular image involved some luck, some skill, and some knowledge of bumblebee behavior. When a bumblebee arrives at a plant, it will generally begin systematically working its way around the plant's flowers. Thus, the observer can predict fairly well where its next floriferous destination will be, and be ready with the camera.

For this image, I had the camera prefocused - but handheld - on the bugloss flower. When the bumblebee came near, I tripped the shutter. A bit of luck, though, and most such shots would be throwaways. I used the remarkably high resolution Canon 5DS-R with the Canon 100mm L macro lens and twin lite flash units. Settings were f/11, 1/200 of a second (camera's sync speed), and ISO 100.

A bumblebee stuffs its head deep within the corolla of a bugloss flower. Gluttonous nectar-seekers, bumblebees rank high among our most valuable pollinators. While this crop of bumbles was smitten with the alien bugloss flowers, they are supremely important to the pollination of our native flora.

While I think the bumblebees in these photos may be Two-spotted Bumblebees, Bombus bimaculatus, I am by no means certain and would appreciate a definitive identification by someone who knows better. There are at least 18 species of bumblebees in the genus Bombus recorded from Ohio, and I find most of them maddeningly similar.

If you would like to learn more about bumblebees, and try to identify those that you see, there is a free publication, the Bumble Bees of the Eastern United States. It contains a wealth of information about these interesting and valuable insects, and can be had for free RIGHT HERE.

Those crazy gentians

A cluster of odd saclike flowers bristles from the summit of a robust Yellowish Gentian, Gentiana alba. A few weekends back, while plumbing the depths of Adams County in southernmost Ohio for rare flora, the inimitable Daniel Boone showed us this station of gentians. Yellowish Gentian is quite the rarity here - listed as an Ohio threatened species - and I'd seen it only a few times prior.

I'd concede that Yellowish Gentian is rather bland in coloration, but that's no reason to refer to it as the "Plain Gentian", as the USDA Plant Database does. Any deficiency of bright hues is more than compensated for by the outrageous floral structure. I mean, this is it - the flowers don't open. They are like little paper bags, and this strange morphology serves them well in weeding out unwanted pollinators, as we shall see.

Sometimes Yellowish Gentian flowers do open a bit, and I helped tease this one apart a bit so we could cast a look inside into the pollinary chamber. We can now clearly see the bowling pin-like carpels capped with their stigmas - the pollen receptacles. Off to the sides of the carpels and not really visible are the stamens and anthers, which contain the pollen.

If you are this flower, the whole idea is to get someone to bring you new pollen - pollen from another plant. Those lime-green stripes on the interior of the petals - petals are known as plaits in gentian-speak - help to lure in the pollen-delivering insect version of the UPS man.

This is another fall-blooming gentian, and it's looking good right now. Bottle Gentian, Gentiana andrewsii, is considerably brighter than the aforementioned species, and has a higher WOW factor. The blue stripes, or nectar guides, are much bolder on this species, but again, they are on the INTERIOR of the flower.

Bottle Gentian is a truly gorgeous species, and I can't imagine anyone not fawning over it for at least a few seconds if they were lucky enough to happen into some. The flowers in this photo are perfectly mature. Note how the flower's summit is tightly closed, and the blue nectar guides so clearly visible on the dissected flower can't really even be discerned, by our eyes at least.

But we don't have the eye-power of a bumblebee.

Bottle-type gentians have evolved an intimate relationship with large, fuzzy bumblebees of the genus Bombus, and these insects have vision that transcends ours in some respects. The bumbles undoubtedly see through the flower, a la Superman X-ray vision, and those showy-looking blue stripes jump out to them. And once a bumble has spotted those lovely azure strips, it must have them, at all costs!

The photo above and the next two were taken by my friend Ethan Kistler, and show the process of a bumblebee invading a Closed Gentian, Gentiana clausa. In the first shot, the bee desperately seeks a path of entry into the flower, and quickly realizes that it must push itself into the tiny gap at the flower's summit. These are brutish, powerful insects, and that's what it takes to penetrate the gentian's defenses.

A bit of prying and prodding, and it's in. This is an outstanding example of a botanical lure - an immobile piece of vegetation that is able to successfully pull in an animal, and make it complete the plant's reproductive cycle.

One just couldn't design a more effective pollinator system than has this gentian. The bumblebee is now completely inside the flower, and what we've got here is the equivalent of a fuzzy pipecleaner tightly shoved into a tube and being twisted about. Not only is the bee thoroughly dousing the stigmas with pollen it has brought over from the last gentian visited, thus cross-pollinating this plant, its fuzzy body is also getting totally dusted with fresh pollen to take to yet another gentian.

Just another of the scores of fascinating plant-insect relationships.