Resurrection of the Genus Endolepis and Clarification of Atriplex phyllostegia (Chenopodiaceae)

Abstract

The genus Endolepis was first described by Torrey in 1860 with E. suckleyi (E. dioica [Nutt.] Standley) as the only species, noting that it differed from species of Atriplex by the presence of perianth parts in the female flowers. Later, Standley described two additional species: E. covillei and E. monilifera. H. M. Hall and Clements merged Endolepis with Atriplex because they thought that the presence of perianth parts in female flowers was variable in Atriplex phyllostegia. It is now clear that this observation was erroneous; A. phyllostegia never has perianth parts in its female flowers. The plants that they examined that had female flowers with perianth parts were specimens of Endolepis covillei; only those with female flowers devoid of perianth parts were specimens of Atriplex phyllostegia. These two taxa differ by several other major attributes including differences in leaf shape, leaf anatomy, fruiting-bract size and shape, fruiting-bract appendages, and flowering habit, and therefore justify taxonomic separation. Also, because the presence of perianth parts in bracteolate female flowers is a rare attribute in the tribe Atripliceae, consistently absent in Atriplex, but always present in Endolepis, the retention of the genus Endolepis, separate from Atriplex, is deemed warranted. We propose that the genus Endolepis comprise two species, E. dioica and E. covillei. The species named E. monilifera by Standley is based on a specimen of Atriplex serenana Nels.