Plagiochasma wrightii Sull.

Plagiochasma wrightii Sull. in A. Gray, Man. ed. 2. 688. 1856
Aytonia Wrightii Underw. Bull. 111. Lab. Nat. Hist. 2: 43. 1884.
Thallus pale-green and glaucous above with a narrow purple border, plane or broadly
canaliculate, purple below, mostly 1.5-2 cm. long and 3-5 mm. wide, with a broad rounded
keel and undulate-crenate, more or less crispate margins; branching dichotomous or ventral,
sometimes with apical innovations; epidermal cells about 22 ju in diameter, with distinct
trigones and a thin waxy cuticle; pores slightly elevated, surrounded by about 6 radiating
series of cells with 2 or 3 cells in each series, the radial walls distinctly thickened; green tissue
rather loose; ventral scales purple, slightly imbricate, the appendages borne singly or in
pairs, ovate-lanceolate, obtuse to acute, entire, more or less constricted and plicate at the
base. Paroicous or autoicous; male receptacle borne behind a female receptacle or on a short
ventral branch; female receptacles borne singly or in a short median row, the stalk mostly
2-4 mm. long, the disc about 3 mm. wide, narrowly concave at the apex, with 2 or 3 apiculate
lobes, the paleae linear-lanceolate, acuminate, entire; spores brownish -yellow, 75-85 /* in
diameter, minutely rugulose, regularly reticulate, the meshes mostly 15-20 /* wide; elaters
7-9 fjL wide, with 2 or 3 spirals, often somewhat coalescent.
Type locality; Texas.
Distribution; Oklahoma, Texas, Arizona and Mexico.