A New Species of Distichlis (Poaceae, Chloridoideae) from Baja California, Mexico

Abstract

Based upon a specimen first collected by S. N. Stephenson, a new grass species, Distichlis bajaensis H. L. Bell, is described. Stephenson hypothesized that this specimen was a hybrid between D. littoralis and D. spicata. Analyses of sequences of nuclear internal transcribed spacer (ITS) and chloroplast ndhF and trnL–trnF and an examination of gross morphology, blade and lemma micromorphology, and blade transectional anatomy demonstrate that this grass is a new species that may be sister to the remaining Distichlis. The blades of D. bajaensis are yellow-green; those of D. littoralis and D. spicata are blue-green. Distichlis bajaensis can be distinguished from D. littoralis by its exserted inflorescences with glumes present and from D. spicata by its short (0.8–1.5 cm) blades with a bend toward the adaxial side. At and distal to the bend, there are antrorse hairs along the medial vascular bundle. Distichlis bajaensis is known from a single large population growing along alkaline seeps in Arroyo Rosarito in Baja California, Mexico.