13a. var. miserrima (E. Fourn.) Reeder
E. arida Hitchc.
E. tephrosanthos Schult.
Spikelets mostly spreading from the inflorescence branches.
2n=60. July–October.
Introduced, uncommon and widely scattered (Colorado to California south to Texas, introduced farther east; Mexico, Central America, Caribbean Islands). Railroads and open, disturbed areas.
Steyermark (1963) considered this taxon (as E. arida)
to be introduced in Missouri, because of the lack of occurrences in natural
habitats. Its taxonomic status has been troubling to botanists for some time.
Koch (1974), in his detailed study of the E. pectinacea complex,
discovered that only the character of the angle of spikelet divergence from the
inflorescence branches consistently separated it from true E. pectinacea,
and that other characters involving spikelet size used by earlier authors did
not separate them well. However, he maintained the two as separate species (E.
pectinacea and E. tephrosanthos), based upon his inability to detect
hybrids between them. Reeder (1986) reexamined the situation, noting that the
spikelet divergence character can be difficult to observe in immature specimens
and that a small proportion of the materials he examined could not be keyed out
adequately using this character. He also suggested that hybrids in this group
would be very difficult to detect morphologically and treated the taxa as
varieties of a single species. Sutherland (1986) noted that plants referable to
E. tephrosanthos in the Great Plains region might be confused with E.
frankii but had consistently wider spikelets with slightly longer glumes
and lemmas. He treated such plants as part of his concept of E. pectinacea
without formal designation of varieties.