Plagiochasma rupestre (J. R. Forst. & G. Forst.) Steph.

Plagiochasma rupestre (Forst.) Stephani, Bull. Herb. Boissier 6: 783. 1898.
Aytonia rupestris Forst, Char, Gen. PL 148. 1776.
? Rupinia lichenoides L. f. Suppl. 69. 1781.
Rupinia rupestris Sw. Meth. Muse. 39. 1781.
RebouUa maderensis Raddi, Giorn. Sci. Lett. Arti— . My 1821.— Mem. Soc. Ital. Modena 20: 3.
1829. Sedgwickia kemispkaerica Bisch. Nova Acta Acad. Leop. -Carol. 17: 1079. 1835. Not S. hemi-
sphaerica Bowdich, 1825. Plagiochasma Aitonia Lindenb. & Nees; Nees, Natiug. Eur. l^eberm, 4: 41. 1838. Anirocephalus italicus Sassi, Atti Riun. Sci. Ital. 1: 160. . 1840.
Jungermannia (Fegatella) ausiralis Tayl.; Hook. f. & Tayl. Lond. Jour. Bot. 3: 572. 1844. Jungermannia (Fegatella) limbata Tayl.; Hook. f. & Tayl. Lond. Jour. Bot. 4: 95. 1845. Plagiochasma australe Nees; G. L. N. Syn. Hep. 515. 1846. Plagiochasma limhatum Nees; G. L. N. Syn. Hep. 516. 1846. Plagiochasma elongatum Lindenb. & Gottsche; G. L. N. Syn. Hep. 519. 1846. Plagiochasma mexicanum Lindenb. & Gottsche: G. L. N. Syn. Hep. 519. 1846. Plagiochasma italicum De-Not. Mem. Accad. Torino II. 18: 476. 1859. Aytonia italica Lindb. Not. Sallsk, Faun. Fl. Fenn. 9: 291. 1868. Otiona rupestris Dumort. Hep. Eur. 148. 1874. Otiona italica Vumort. Hep. Eur. 149. 1874. Rupinia italica Trevisan, Rend. 1st. Lomb. II. 7: 785. 1874. Rupinia mexicana Trevisan, Mem. 1st. Lomb. 13: 437. 1877. Rupinia elongata Trevisan, Mem. 1st. Lomb. 13: 437. 1877. Rupinia limbata Trevisan, Mem. 1st. Lomb. 13: 437. 1877. Rupinia australis Trevisan, Mem. 1st. Lomb. 13: 437. 1877. Aytonia lanigera Spruce, Trans. Bot. Soc. Edinb. 15; 568. 1885. Aytonia australis Stephani, Hedwigia 28: 129. 1889. Aytonia elongata Underw. Bot. Gaz. 20; 66. 1895. Aytonia mexicana Underw. Bot. Gaz. 20; 66. 1895. Plagiochasma lanigerum Stephani, Bull. Herb. Boiss. 6: 788. 1898. Aytonia Evansii Haynes, Bull. Torrey Club 34: 57. 1907.
Thallus pale-green and glaucous, pigmented with purple below and along a narrow border above, mostly 1-2 cm. long and 5-7 mm. wide, with a broad rounded keel and plane or slightly canaliculate on the upper surface; branching sometimes dichotomous, sometimes ventral, often with apical innovations; epidermal cells mostly 18-30 m in diameter, with small trigones and a waxy cuticle; pores not elevated and very inconspicuous, surrounded usually by a single circle of 4-6 cells, the radial walls often somewhat thickened; green tissue fairly compact; ventral scales deep-purple with one or two, rarely three ovate-lanceolate to lanceolate appendages, acute to acuminate, entire, and slightly or not at all constricted at the base, Paroicous or autoicous; male receptacle sometimes borne on the same branch as the female, sometimes on a more or less elongate male branch ; female receptacles borne singly or in a median longitudinal series, the stalk usually only 3 mm. long or less, the disc mostly 2-3 mm. wide, concave, with (usually) 2 or 3 apiculate lobes,the paleae abundant, narrowly subulate with elongate filiform points, entire ; spores yellowish-brown, 70-90 ju in diameter, minutely rugulose with regular though often incomplete networks on the faces, the meshes mostly 15-20 ju wide; ■elaters about 10 m wide, with 2-4 spirals, sometimes more or less coalescent.
Type locality: Madeira.
Distribution: New Mexico and Arizona, south into Mexico; Jamaica; also in South America, Europe, the Atlantic Islands, Africa, Asia, and Australasia.