Confusing comb-burs

It's that time of year when the comb-burs (Pectocarya spp.) are popping. Four of the local species are darn near identical vegetatively; three of them are fairly common locally (northeastern Maricopa County) and one is rare. This observation shows the differences in the fruit of the three more common ones, and this one is of the local rarity, P. setosa.
Some description based on a guide I wrote some time ago:
P. heterocarpa: Tips of nutlets bent slightly forwards. Marginal teeth are not spreading; teeth are fewer to missing on one nutlet.
P. recurvata: Nutlets curved backwards. Marginal teeth on fruit regularly spaced, hooked. This is the most common species of the three locally.
P. platycarpa: Swollen margin. Teeth irregularly spaced, hooked, with fattened base; teeth smaller and more numerous at the tips of the nutlets.
And for a bonus here is its slightly larger cousin, Harpagonella arizonica. Fruit differ from the four-nutlet, x-shaped plan of the pectocaryas.

由使用者 stevejones 在 2021年03月04日 00:15 所貼文