Tag Archives: botanical nomenclature

When is a Flower Flowers?

As you glance at the picture below how many flowers do you see?

tagetes1

Head shot of a marigold

I do not know exactly how many are visible, but the answer is a relatively large number. Each of the structures that you feel inclined to call a petal is actually a flower in this case. The entire structure is called a head (which consists of ray flowers that look like petals and in the middle you’ll find disk flowers that look like tubes). Welcome to the crazy world of Asteracaeae.

ray_floret1

An individual marigold ray flower.

 In the case of a mum the ray flowers and disk flowers are a bit easier to spot.

dendranthema1

Since this is a Dendranthema maybe it should be called a ma?

So the individual parts look like this (well, almost like this, the picture below was taken with a different Dendranthema cultivar).

diskandray_florets

Disk and ray flowers of a mum.

So as a bit of a review, how many flowers are featured in this picture?

dianthus_frostyfire

Dianthus 'Frosty Fire'

Ah, this is a trick question. Dianthus is in a different plant family, so it just one flower. The things that look like petals are actually petals. Of course you could argue that the answer is two based upon the glimpse of a second flower on the left margin.

Back to the Asteraceae.

aster1

An abundance of flowers.

By the way, if you ever refer to a head of flowers as an individual flower I won’t think less of you.

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