Field of Science

Friday Fabulous Flower - Kohleria

Gesneriaceae is best known for African violets, but many other members are showier and even easier to grow, of course, my F1 grows better African violets, so the Phactor is not the best authority on their cultivation. This neotropical species, probably Kohleria eriantha, grows as a very vigorous, almost constantly flowering, sub-shrub in our glasshouse. The reason people like this genus is obvious; the flowers are fairly large, bright in color, fuzzy, and the corolla has very bold nectar guides. Nectar guides like this usually absorb UV light and the areas between reflect it, so in those wavelengths, they are very bold. This tells you they are not adapted for human eyes. Numerous hybrids exist, but in general they are avoided in our use as real species are prefered for teaching botany. If you wish to learn how flowers work these are a nice example of how a "bisexual" (bisporangiate really) flower uses movement of floral parts and sequential functionality to promote outcrossing. When this flower first opens the two pair of stamens are positioned at the top and front of the corolla tube thus ready to daub pollen on the back of any visitor, which based on the floral size and features, will be a bee. The style is above and below the anthers, out of the way, and the bilobed stigma remains closed. After a day of dispersing pollen the spent anthers fold back, and the style takes their place with an open stigma, thus changing the flower to pollen accepting. It's a good exercise to assign this to students for them to figure out how this flower works.

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