Purple Prairie-Clover (Petalostemon purpureus) This wild legume (member of the pea family) often grows in thick patches, with low, spreading stems. The small, thimble shaped florets, containing many tiny flowers arise at the end of the stems and reach up to 40 cm high. It blooms by mid-July. Plant breeders are working with purple prairie-clover and other species to try and produce a native equivalent to alfalfa.