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.)

At specific rank, the epithet suckleyi clearly has priority. Stutz et al. (1993) resurrected Endolepis Torrey and placed within it two completely disparate species, E. dioica and E. covillei Standley [Atriplex covillei (Standley) J. F. Macbride]. The interpretation of the genus by Stutz et al. stands on the presence of perianth segments subtending the ovary within the fruiting bracteoles, lack of Kranz leaf anatomy, and other more equivocal characteristics. The shared features hardly indicate near affinity, however. The two taxa are otherwise grossly dissimilar. Fundamentally, the genus Endolepis as resurrected by H. C. Stutz et al. stands on the basis of a single character: the presence of perianth segments. Kranz anatomy rises and falls, both within subg. Atriplex and subg. Obione. Thus, coincidence of the non-Kranz criterion is subject to interpretation. Perianth segments subtending the ovary within the enclosing bracteoles, per se, appear to be of independent origin. And, the peculiar nature of the staminate calyx in A. suckleyi (a major determining condition in establishment of the genus Endolepis by Torrey) is not present in A. covillei. Certainly the two species included within Endolepis appear to be as closely allied to other species of Atriplex as they are to each other.

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