Flora of North America species comparison

Froelichia floridana ranges from broad-leaved stout herbs surpassing 1 meter in height to much-branched plants forming bushes to 2 meters in diameter and single-stemmed, erect herbs 1 dm in height. Much of the variation in the species has been difficult to ascribe to either geographic or ecologic differences and reflects inherent genetic variability and wide environmentally induced plasticity. Although specialists and taxonomists have implied the existence of well-delineated morphologic taxa with a strong geographic correspondence, this is not always true, and, in fact, one encounters typical specimens of any given variety sporadically throughout the range of the species.

Some variability in Froelichia floridana is clearly attributable to geography, principally in terms of general morphologic trends. There is a cline toward long, narrow, almost linear leaves as one moves east along the Gulf Coast and into Florida. This would culminate in the little-known var. pallescens Moquin-Tandon, a linear-leaved form (leaf length more than eight times width) from peninsular Florida. Additional variation ascribable to geography is observed in plants traditionally included in F. drummondii, these being large, stout plants with broader leaves, more obtuse leaf apices, and more densely fulvous pubescence on the abaxial surfaces of leaves. Plants of this form are generally restricted south of the Brazos River and continue to the southern extent of the range in Kenedy County, Texas. Further work examining this variation using micromorphology or molecular markers may elucidate a reliable means to identify intraspecific taxa within F. floridana.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Froelichia drummondii has generally included robust plants with typically obtuse leaf apices, here assigned to F. floridana, from southern Oklahoma through central and southern Texas, and perennial plants treated here as F. interrupta var. cordata. Due to this broader species circumscription, most specimens in American herbaria are not correctly assigned. My field and herbarium studies have indicated that an interpretation of this taxon as restricted to the plains of south Texas probably most closely follows the original circumscription by Moquin-Tandon, and thus it is provisionally recognized here at the species level.

Froelichia drummondii is intermediate between F. interrupta and F. floridana, and it is intermediate in the transition from perennial to annual species in the genus. Designation as a variety of F. floridana, as has been done by recent authors, could be supported, but the shorter and darker filament lobes unique to the perennial taxa, a tendency toward shorter flowers, and the restricted range strongly support its recognition as a separate species. Further taxonomic work may verify the distinctiveness and relationship of this taxon to the remainder of the genus, particularly to F. floridana.

(Discussion copyrighted by Flora of North America; reprinted with permission.)