Hi, I am using this wonderful guide to learn about asteraceae identification.
I am stuck at step 2b, specifically this part “Capitula with zygomorphic ray flowers”.
From my understanding zygomorphic means that the flower can be split symmetrically down the middle in one orientation, I can see for example how many orchids fit this description.
The guide uses Erigeron hyssopifolius as an example of a capitula with zygomorphic ray flowers, but to me this seems like the exact opposite, to me it looks like this can be divided in any direction(s) and it would still look the same.
On a sidenote: can the mods confirm that my botanical question posts are allowed in Nature Talk, I don’t see other people making similar posts frequently so I am worried that this is discouraged, I hope not because the forum has been so helpful.
Here the “ray flowers” are the white ones, all around the capitulum – surrounding a bunch of yellow flowers. Now if you look at one of these white things closely (you’ll need a hand lens)… it’s zygomorphic.
Adding to what @GeolTel wrote, the capitulum is a flower head or cluster of small flowers (or florets) that make up your white-and-yellow Erigeron “flower”. The capitulum is radially symmetrical, but the individual flowers are a mix: The ray florets are zygomorphic because each one consists of a flower tube plus a white ray or lamina extending out to one side. The yellow disk florets in the capitulum are actinomorphic or radially symmetrical because they don’t have a ray or lamina extending to one side. Some Asteraceae species have only ray flowers (genus Lactuca is one example, https://www.inaturalist.org/taxa/53107-Lactuca-serriola ), and some have only disk flowers (like Helenium thurberihttps://www.inaturalist.org/taxa/163592-Helenium-thurberi ), but many have both ray and disk flowers. Asteraceae is a fascinating but difficult family, with a wide variety of forms around the world.
I thought the description was meant for the ray florets as a whole, but now I see it.
I also didn’t know that the ray florets had reproductive organs of their own, I assumed that all the nectar bearing florets were disk florets and the ray florets were simply the petals, the more you know!
Our rain daisies produce 2 shapes of viable seed – both the obvious seeds which are disc shaped, but also the ‘little sticks’. I presume coming from ray florets and disc florets. If you have a packet of seed, don’t discard the twiggy bits.
