Flora of North America species comparison

Endolepis covillei was treated within the synonymy of Atriplex phyllostegia (Torrey) S. Watson by H. M. Hall and F. E. Clements (1923).

H. C. Stutz et al. (1993) placed Atriplex covillei within Endolepis, based in large part on the presence of a perianth subtending the pistil within the fruiting bracteoles and on the lack of Kranz anatomy in the leaves. The pattern of venation is, nevertheless, very similar to that in species with Kranz anatomy. The presence of perianth scales in the pistillate flowers of A. covillei has been regarded as evidence of relationship with A. suckleyi. Despite placement of these taxa within Endolepis by Stutz et al. Atriplex covillei is possibly more closely allied to the morphologically similar and partially sympatric A. phyllostegia than it is to strongly dissimilar and the distantly disjunct A. suckleyi. Stutz and his associates placed great emphasis on the presence of reduced perianth segments subtending the pistil within the fruiting bracteoles of A. covillei. Calyces per se, otherwise known only in A. suckleyi and A. pleiantha, probably have arisen independently. Their presence does not necessarily indicate a close relationship. Stutz et al. pointed to other differences aside from the calyx of the pistillate flowers, and it is apparent that the two entities can stand as distinct species. To segregate A. covillei within a separate genus and to ally it with a species to which its relationships are obscure at best, stretches logic beyond reason.

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

Species 1.

The pattern of venation in this section is very similar to that of the closely comparable Atriplex phyllostegia, even though the veins lack the associated C4 arrangement of chlorenchyma cells surrounding the veins. The plants differ otherwise as noted in the descriptions. Placement of this species within the segregate genus Endolepis by various workers is based on two morphologic characteristics considered to be of fundamental importance, i.e., the lack of Kranz leaf anatomy and the presence of sepals subtending the ovary within the fruiting bracteoles. Sepals of staminate flowers lack the distinctive crests seen in A. [Endolepis] suckleyi, a feature on which the genus Endolepis was based. The placement of A. covillei within Endolepis, while convenient, does not take into account the overall similarity of this species to the evidently related A. phyllostegia. Neither does it take into account the potential for recurrence of sepals subtending the ovaries as possibly derived features.

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