chelle said:So, what's still showing in this picture, Jay?
Are they florets above ovaries?
These are the disk florets (or disk flowers). The ovaries are part of the disk florets, not separate.
So you see, what most people think of as "the flower" can be very confusing when picked apart and separated into botanical parts. The flower that most people think of has one (or one set of) each part (corolla, petals, calyx, sepal, ovary(s), stamens, etc.). But natural variations are practically infinite. With some species like tithonia and zinnia (mainly those in the Asteraceae family), "the flower" as a regular person would understand is actually many individual flowers, botanically speaking. In this case, the many individual flowers are ray flowers and disk flowers.
A botanist isn't interested in how a flower looks; rather, the importance is what actually makes a flower look like it does. Dividing a flower (and all parts of a plant) into individual parts and analyzing where these parts arise in the evolutionary process is the key to discerning the relationships between different plant species or between other groupings of plants. This is why it is so critical for the botanist to differentiate a petal from a corolla, for instance. All these clues are used to support their taxonomic categorization of species. This is how they know, for instance, that a Pointsettia (
Euphorbia pulcherrima) is related to a Candelabra cactus (
Euphorbia lactea). Who else would've thunk it?
woofie said: So, would a zinnia be considered a disk flower? AND a ray flower? Or is it a ray flower that includes disk flowers?.
So if I have explained sufficiently, the answer should be obvious: a zinnia flower as a regular person would understand, is actually compose of many
separate flowers. Some of these flowers are ray flowers and some are disk flowers.
