|Iris versicolor on the bank of a river|
Today's post is a sort of remedy to that previous post.
Let us begin with a basic understanding of floral anatomy. All flowers develop along the same fundamental plan, with assorted modifications. The more a flower deviates from the basic or foundational plan, the more 'derived' it is considered to be. Generally, more derived traits indicate greater evolutionary change over time relative the ancestral condition or trait.
sepals, which usually serve primarily as a layer to protect the developing flower in the bud stage, and sometimes also serving as structural support for petals. The next ring in contains the petals, which are of course the primary visual attractant structure. Assorted derivations of the basic petal plan can also help manipulate the orientation of a pollinator approaching a flower, thereby increasing precision of pollen transfer, or to restrict access of pollinators to various parts of the flower, thereby reducing resource loss to robbers or ineffective pollinators. In some families of flowers (notably, Lilaceae, the lily family, and Asparagaceae, the asparagus family), sepals serve similar attractive and structural functions to petals and are not immediately distinguishable from them visually. In these cases, we refer to both sepals and petals as tepals. Below, a photo of Lilium philadelphicum (wood lily) shows a great example of tepals. Notice the lack of any visible sepal, and also if you look closely where the tepals attach to the stem you can see that there are three attached lower and three attached higher; those attached lowers are derived from sepals and those attached higher are the 'original' petals.
|Lilium philadelphicum, example of tepals|
So, back to I. versicolor. Now that we have a reasonable understanding of floral anatomy, something seems odd about this flower.
|Iris versicolor, top view|
The flowers of I. versicolor are highly derived; irises are of sufficient anatomical interest that there are actually special names for all the structures for these irises, but they are all analogous to the layers described above. I'll take you guys through these layers again from top to bottom and point them out with photos.
The petals are actually the three things sticking up in the middle, referred to as "standards" (somebody was way too enthusiastic about the quasi-military and flag-based metaphors in naming the parts of an iris).
|Iris versicolor - style crest, falls, signal|
|Iris versicolor - stigma, style crest, falls, signal|
This particular species of iris, I. versicolor, is native to eastern North America (range map here). It is an obligate wetland species , found exclusively where there is sufficient water (lakesides, marshes, ponds, streams, etc). It is the provincial flower of Quebec.