1 June 2012

Botanical Look At Daisies

While grubbing about in the grass to take the meditative film of daisies I noticed some of them were past their best – a state I can sympathise with. The white petals were falling off and the yellow middle bit was turning red and changing shape. What’s going on? The biologists and horticulturalists amongst us might know (ssh now, don’t spoil the fun), but for the rest of us here’s my stab at an explanation.

Firstly that pretty round daisy flower is not a single flower but a collection of many. They are called composite flowers because they are made of a compound inflorescence of hundreds of tiny florets. The little yellow ones, called disc florets, don’t have any petals (but they do have corollas which are the yellow bits we see), but the florets on the outside, ray florets, do – the long white ones. Still with me? Maybe this will help:

Here’s a couple of images of the aged daisies on my lawn. It looks like something is happening to the disc florets.

daisy disc florets

If we borrow a picture from an obscure American university the structure of the disc florets becomes clearer.

So if I understand it right (and I don’t), then my style, anthers and corolla are decaying and the ovary has now turned into a seed. Which then disperses.

OK the scientists amongst us can now pipe up ...
  • Why has the upper portion of each disc floret turned red?
  • Why does the central area (the receptacle) dome upwards?
Admittedly these aren't the most pressing questions of the age, but when you're nose to floret you just can't help wondering.