4. Crossidium squamiferum (Viviani) Juratzka, Laubm.-Fl. Oesterr.-Ung. 127. 1882.
Barbula squamifera Viviani, Ann. Bot. (Genoa) 1(2): 191. 1804; Tortula squamifera (Viviani) De Notaris
Plants 6-10 mm. Leaves deltoid-ovate, oblong-ovate or lanceolate, 0.6-2 mm, margins recurved to erect distally, usually undiffer-entiated, apex obtuse or rounded, serrulate, with abaxial papillae, piliferous; costa excurrent, with an inconspicuous abaxial epidermis, filaments of 4-10 cells, cells cylindric to subspheric, [thick-walled, terminal cell rectangular, subspheric or conic with 2-5 solid papillae; cells of leaf base 11-70 µm, medial and distal cells 9-33 µm, smooth, thick-walled. Sexual condition gonioautoicous. Seta 5-20 mm. Capsule urn short-cylindric to ovoid-cylindric, 1-2.7 mm; operculum 0.6-1.1 mm; peristome short, nearly straight, cribose at base to long and strongly twisted, 198-1160 µm. Spores spheric, 9-22 µm.
Varieties 2 (2 in the flora): North America, nw Mexico, Europe, Asia (India), n Africa, Atlantic Islands (Canary Islands).
Crossidium squamiferum is a distinctive species characterized by a whitish marginal area on the distal half of the leaves, thick-walled distal leaf cells, a long hyaline hair point, thick-walled filaments ending in a papillose terminal cell, and the gonioautoicous sexual condition. North American specimens without sporophytes from Arizona, California, Colorado, and Utah have been studied, but these cannot be satisfactorily referred to an infraspecific category. The type specimen of C. succulentum is also sterile.