Friday Fabulous Flower - tropical springiness

It's been awhile since there's been a FFF posted. Tropical plants do something sort of strange each year.  A lot of them flower in late February or March in the glasshouse, yet most of them are thought to be day-neutral for flowering.  This means that they don't need long nights to stimulate flowering, yet that's just how they act. Of course the glasshouse is also warming up a little and getting a lot sunnier.  At any rate here's a member of the Bignoniaceae, a family of largely tropical trees, shrubs, and lianas, a family with fairly large, pretty colorful flowers. The trees and shrubs also tend flower in a big-bang of blooms making for some pretty spectacular displays. This shrub is called the Cape Honeysuckle (terrible name that points to the wrong family), Tecomaria capensis, a fairly common ornamental, in fact probably in the category of UTF, ubiquitous tropical flora. But it's just so cheerful, so bright, such a welcome relief from the bitter cold and bleakness outside. You should be able to guess that such flowers are adapted for bird pollination based on the color, the lack of odor (scratch & sniff), and the exserted stamens and stigma.  Enjoy!

Unique bird pollination adaptation - poofty anthers

Here's a link to a newly published study describing and documenting a very unique bird pollination adaptation. The anthers have a "spongy" bulb of tissue and they are attractive to birds.  When a bird grasps the "bulb" to pluck it from the flower, the tissue collapses and blows a puff of pollen onto the face/head of the bird, thus placing the pollen in a location to be transferred to another flower's stigma. This is a totally unique anther adaptation. The common ornamental called the "wishbone" flower (Torenia) has levers on its anthers that when pushed squeeze out pollen like toothpaste from a tube, but that's still quite different.  In the bird pollination paper the flowers are part of the Melastome family, a group of plants that tend to have large, gaudy stamens (for example), but TPP has never seen anything like this.  Cool. 

Friday Fabulous Flower - a screwpine

Although most tropical plants are day neutral, and although most of the plants in our glasshouse are tropical, an great deal of flowering occurs now as the days begin to get longer again.  Here's and interesting, and in our glasshouse, unreliable flowerer, a member of the screwpine family (Pandanaceae), Freycinetia multiflora.  As can be seen the stem and foliage give this scrambling shrubby vine a bamboo-y sort of appearance, and it can climb by means of adventitious roots to the tropical forest canopy.  This one actually isn't in flower yet, but the flowers are tiny and borne on three club-shaped inflorescences hiding (for now) underneath the inner whorl of orange-sherbet colored bracts, which are the attractive part. The smaller image shows one of the inflorescences emerging; these are dioecious plants, and this one bears staminate flowers.  According to the literature, pollination is basically vertebrate, nectar/pollen feeding bats and birds, although possums may also effect pollination. On the whole is has a rather unusual look to it, but then again, all screwpines have a strange sort of look to them.

Friday Fabulous Flower - Cardinal Flower

This Friday's fabulous flower is Lobelia cardinalis, cardinal flower, although other than its scarlet color, it doesn't resemble a bird at all. The plant is usually about a meter tall, and in the late summer a stand of cardinal flower can make a pretty spectacular display rising above their favorite roadside ditch betraying their preference for wettish places. Like many bright red flowers these are displayed turned slightly upward, without any noticeable scent, and a goodly amount of nectar. Floral biologists anywhere recognize this suite of traits as indicating bird pollination. Distributed widely across eastern North America, the sole pollinator is the ruby-throated hummingbird. It may be that when the cardinal flower finishes flowering at the northern end of its range, that's the signel for hummingbirds to begin their migration southward. Lobelia's in general have flowers with a strong bilateral symmetry, and cardinal flower is no exception, with three corolla lobes out front showing the way to the tube of nectar. Two small corolla lobes curve to the side, sort of staying out of the way. The stamens are fused into a tube at the top through which the style and stigma grow and eventually emerge. Before the stigma opens a ring of bristly hairs encircling the style just below the stigma look a bit like a small bottle brush. When a hummingbird makes contact with the staminal tube and pushes it back just a little, this causes the stationary and bristly style to push pollen up and out of the tube, and action that has been called a "pollen pump", but to me it's a test tube and brush. Try it; you can actuate the mechanism yourself. These flowers are in the pollen dispersing phase. After the flower finishes its pollen dispersal, the stigma opens, the bristles fold back to trap any self pollen remaining, and the flower is ready to accept pollen from the next hummingbird to visit.

Attractive display for dispersers of tropical plant

It's been awhile since blogging about the tropics. Those of us who study flowers are used to seeing diverse displays to attract pollinators. This is also true for fruit displays attracting seed dispersers. Now of course both of these are floral displays, but at different times in the flower's functional life, and most people just aren't used to thinking of fruits as flowers at the time of seed dispersal.

What is truly unusual is to have the same display being used for attracting both pollen and seed dispersers because they are almost always at different times and for different organisms. This a member of the Gesner (African violet) family from Costa Rica, Columnea purpurata, and the leaves are arranged to make a flat array along a stem forming a canopy over its flowers and fruits. So this is photographed from below as this branch extends out over your head (it grows as an epiphytic shrub). Both the flowers' persistent calyx and the subtending bract are bright orange and hairy, and the entire cluster of flowers, at both dispersal stages, produces a single display. At the right hand end of the cluster you can just see a yellow corolla tube and at the left hand end an orange berry is visible (arrows). The reason one display works for both dispersal stages is that birds are the dispersers of both pollen (hummingbirds) and seed (diverse frugivores), and such a large, bright display is needed in the shady understory.

Relief from winter doldrums: 2. Visit the greenhouse

Lincolnland is still in the grips of cold and snow, although it does look pretty right now. Usually the midwest is just sort of snowlessly bleak. But for the second in my series on seeking relief from the winter doldrums, let's visit the greenhouse and see what's going on that isn't monochromatic.

This is a pretty spectacular flower, Thunbergia mysorensis. As the specific epithet suggests, this vine is native to southern India. A pair of reddish bracteoles encloses the base of each flower providing a constant display as the flowers open sequentially bottom to top. Morphologically; the inflorescence is pendent so the bottom is at the top and each flower twists 180 degrees to attain the correct orientation. The flowers produce copious nectar, often enough to drip over the bottom lip of the corolla, and are bird pollinated. The stigma and stamens occupy the top of the corolla tube where depending upon the stage of flowering (pollen accepting or pollen dispersing) one or the other makes contact with the visiting bird's head. Enjoy.