Botany Of The Cosmos

Day 330: What is "a flower?" Maybe it's not as easy to define as it sounds. Let's take a Cosmos blossom and break it down. Cosmos belong to the family of composites (Asteraceae), a word which might give you a clue that there's more going on here than meets the eye. In the most basic terms, there are two types of "flower" in the makeup of a Cosmos bloom: ray flowers (the "petals") and disk flowers (the "center"). What we commonly refer to as a Cosmos "flower" is in fact a head bearing many small flowers. You can see this in the closeup example, upper right. If you examine the disk through a hand lens, the smaller flowers will become apparent. Depending on the plant species, disk flowers may be a mix of male and female as they are in Cosmos, or male and female flowers may be borne on different heads, in which case they are referred to a "staminate" or "pistillate" depending on the sex. The microscope views show both sexes of Cosmos disk flowers, the brown stamens of the males obvious in the center right image, females lower right. The "birds-and-bees" of botany is quite a complicated process!

Delphinium Glareosum, Rockslide Larkspur

Day 277: No rarity here, just a blue that'll knock your socks off! Rivalling Gentian and Monkshood for intensity of colour, Rockslide Larkspur (Delphinium glareosum) puts on a rather weedy but spectacular show, its flowers loosely arranged in an open inflorescence rising up to 30 inches above fan-shaped, mostly basal leaves. A cousin to "garden-variety" Delphiniums, this Larkspur's central "bee" provides our botany lesson for today.

As a generalization, flowers are comprised of four whorls: the calyx, the petals, the stamens (filament and anther) and the stigma/style/ovary. Not all flowers contain all these elements, and when one is lacking, they are referred to as "incomplete." In the case of Larkspur, its petals are white (the second whorl) and its sepals (segments of the calyx) are blue (the outer whorl). Its reproductive parts are concealed by the petals, a factor which limits the types of insect which can pollinate the plant. Only bugs of a specific size/shape or the deft tongue of a hummingbird can penetrate its "inner sanctum" to ensure future generations of this blue beauty.