Noses and Navels - Part 1: Noses

Orchids have noses and Roses have navels (which I will explain in another posting). At least those are a couple of thoughts I fall back on when attempting to explain flower and fruit structure to a group. Examine an archetypal orchid - such as Cattleya. There are only seven parts of the flower - three of the petal-like objects are the sepals. We know they are sepals because they are the group of three "floral leaves" that originate at the same point, below and outside the petals - even alternating with the petals in exact attachment. The sepals are the flower parts that made up the outside of the developing buds.

Once the flower opens (botanists call the opening process anthesis,) the inner surface of the three sepals have the look and texture of petals. Face to face with an open Cattleya, you see that the three sepals make a triangle, with one pointing up (once you determine what "up" is,) and the other two pointing to the corners of the triangle base.

Alternating with the narrow sepals are three petals, but only the upper two look like normal petals. These are called laterals; in Cattleya they are broader and more colorful than the sepals. The tips of the lateral petals make the two upper corners of an upside-down triangle. The apex of the triangle is at the bottom, made by the third petal, which is the showiest and most characteristic petal of the Cattleya. That petal, the labellum (or lip,) is the landing platform for visiting insects in naturally occuring Cattleyas; its beauty and complexity is all about attracting and positioning visiting insects and has nothing to do with amusing humans.

Though the lip is the most conspicuous single element in the Cattleya flower, the business end is the remaining seventh flower part - a white, plastic-seeming part that looks like a nose to me. I know it is not a nose; orchids can't have noses. It is the column - the sleek device that combines all of the reproductive structures, the male and female parts we expect to find in a flower. If you examine the column closely, it has a lot of elegant structure. It arches forward, pairing off with the lip in a predictable and precise form - the two structures working together to create the mechanism by which orchid flowers are pollinated.

At the tip of the column, there is a hatch, underneath which you will find the pollen masses. The hatch and pollen together are considered to constitute all you can easily distinguish as the flower's single anther. Immediately back/behind/below the anther, the column has a long sticky chamber - on its underside, facing the base of the lip. This is the stigmatic chamber - the surface is the stigma that must receive pollen for an orchid flower to be pollinated. In most other kinds of flowers, the stigma sits proudly on its own stalk (the style) - easily visible in the center. Many flowers have separate stigmas, each on their own style as part of their own separate pistil; others have a single stigma that may have obvious lobes corresponding to separate chambers in the ovary.

By comparison to most non-orchid flowers, the Cattleya is remarkably engineered - simplified and modern in form based on a history of multiple and complex parts. But the column is what orchids have that is all about pollination, thus leading to fertilization and sexual reproduction. So you might say that Orchids have a nose for sex.

As a side note, from childhood, I remember the big deal about orchids in corsages was often simply deciding how to wear them.... what is right side up and what is upside down. When in flower, the lip of the Cattleya is down, below the column, the natural position that relates to how the flower is visited by pollinators. Curiously, to achieve this position, an orchid has to grow in a way to reposition the lip - which in its early formation is positioned on top. We call this resupination - setting the lip in a supine, or laying down, position. In the Cattleyas it happens through a twisting in the stalk (which is yet another curiosity, because it is the ovary.) Which leads to a corny ending; through a twist of fate, orchids keep their noses up in the air.