Monographs Details: Plagiochasma muenchianum Steph.
Authority: Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)
Description:Species Description - Thallus 6-7.3 mm wide, yellowish green, sometimes partly tinged with purple, with purplish margins; apical adventitious branches infrequent. Epidermis smooth; epidermal cells (24-)28-35 × 21-24 µm, usually with large, sometimes nodulose trigones. Epidermal pores 8-15 per mm2, slightly raised above epidermis, 24 µm diam., bounded by 3(-4) concentric rings of 6-7(-8) cells, radial walls thickened. Ventral scales purplish, with border of 1-2 rows of light-red or hyaline, sinuose cells; appendage l(-2), widely triangular or ovate, apex acute, with 1-2 cells apically, light red or hyaline, widest basally, 15-22 cells wide, constricted and horizontally plicate, length/width ratio 1.4-1.6:1; margins with 1-2 rows of smaller cells, some with papillae, sometimes with 1-2 large, pluricellular teeth. Male receptacle dorsal, rounded to reniform, with 25 antheridia. Scales of male and female receptacles hyaline, or partly tinged with purple, acute, with row of 1-3 cells apically, margins with scattered teeth and papillae. Archegoniophores dorsal, stalk 1-2 mm long, with slightly thickened, dark purplish epidermal cells. Involucres 2-3, purplish. Spores 82-94 µm diam., brown, with complete areoles on both faces, ridges tuberculate. Elaters with 2(-3) helical bands. Gametophytic chromosome number unknown.

Discussion:Plagiochasma muenchianum is most closely related to P. wrightii and P. jamaicense. In P. wrightii, the thallus is narrower, the epidermis finely granulose, and the pores smaller. In P. jamaicense, the appendages of the scales are smaller and narrower, without teeth, and the thallus produces numerous apical adventitious branches.
Distribution:Mexico North America| Chiapas Mexico North America|