Mexican Coriander, Sweet Marigold

Mexican Coriander (Eryngium foetidum) which I was told to cut off the flowerstalks as soon as they appear. Why?

Once flowers appear the plant will put all of its energy into producing seed and the plant will stop producing fresh leaves. Since we want the leaves we try to foil its attempt to produce seeds instead.

Sweet Marigold (Tagetes lucida), are the flowers edible?

Yes, most definitely. The leaves, of course, have a strong anise scent and flavour, but the bright-coloured flowers are excellent as an edible flower for salads and many other dishes.