Viewing post #461633 by Leftwood

You are viewing a single post made by Leftwood in the thread called For the DB: botany question regarding disc flowers vs. ray flowers.
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Aug 5, 2013 9:22 PM CST
Name: Rick R.
Minneapolis,MN, USA z4b,Dfb/a
Garden Photography The WITWIT Badge Seed Starter Wild Plant Hunter Region: Minnesota Hybridizer
Garden Sages I was one of the first 300 contributors to the plant database! Plant Identifier Million Pollinator Garden Challenge
Yes, a good example of disk flowers (or disk florets).
But I wouldn't enter it as an example without showing the entire flower head (including ray flowers). This is already a difficult concept to grasp.

Ray flowers (or ray florets) are not botanically comparable to tepals, and so could never be substituted, one for another, even in different flowers.
---- "Tepal" is a term used to encompass both petals and sepals, when the flower does not have a strong differentiation between the calyx and the corolla.
---- The term "ray flower" designates a type of individual flower that would include all parts that might be present: sepals, petals, ovaries, stamens, etc. Tepals, if they were present, would only be part of the ray flower.

In the case of Tithonia, there are no tepals, because the colorful part that most people would call an individual petal is actually the corolla (not a single petal or sepal) of one ray flower. Thus, the photo above shows 13 ray flowers (and about 90 disk flowers).

Nature creates huge variations in parts of flowers (indeed all parts of a plant). For instance, depending on the plant, a sepal can look like a petal, a leaf, a bristle, a nub, a cone, or be absent entirely. Most plants in the world do not have ray flowers. So while there can be similarities within groups of plants, each will be different.
When the debate is lost, slander becomes the tool of the losers. - Socrates
Last edited by Leftwood Aug 5, 2013 9:24 PM Icon for preview

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