serotinal
Occurring in or pertaining to late summer.
The psoraleas, prairie clovers and blazing stars would probably occur to all us among the most the most abundant of the secondary species in the vernal, estival and serotinal aspects of the prairies respectively.
Where it comes from
From serotine + -al (suffix forming adjectives).
Adapted from the Wiktionary entry serotinal (CC BY-SA 4.0).