Bryol. Univ. 1: 471. 1826,.
Plants 3 mm, gregarious or in loose, low tufts, forming low rosettes, appearing stemless, light to olive green. Leaves 3 mm, erect-patent, flexuose when dry, from lanceolate base gradually contracted into a long, fine, straight, concolorous, distinctly canaliculate subula; margins serrate in the distal part of the leaves; alar cells scarcely differentiated; basal laminal cells hyaline, thin-walled, rectangular; distal laminal cells thick-walled, rectangular, ca. 4: 1; costa filling 1/2–2/3 of leaf width, excurrent, in transverse-section with large, empty, adaxial hyalocysts and abaxial groups of stereids, abaxially smooth. Specialized asexual reproduction by colorless, multicellular, long-cylindric rhizoidal tubers, 300–700 µm long, deciduous leaves and small brood leaves produced at stem tips. Sporophytes not present in North America.
Habitat: Bare soil, also base of trees and old pine stumps in wet acid meadows and swamp forests
Elevation: 0-50 m
Fla., La., Miss., s South America (Argentina), s South America (Brazil), s South America (Chile), w Europe, Asia (China), c, s Africa, Atlantic Islands (Azores), Atlantic Islands (s Iceland), Atlantic Islands (Madiera), Pacific Islands (New Caledonia), Pacific Islands (New Zealand), Australia
The description above refers to North American plants of Campylopus pyriformis—specimens from other parts of its range have a somewhat different appearance. This species was first recorded for North America (T. Arts and J.-P. Frahm 1990) based on collections made by W. D. Reese. The occurrence in North America at only three localities in Louisiana and Mississippi, and an additional unpublished record from Florida, can perhaps be explained by introduction facilitated by the presence of rhizoidal tubers. It may therefore be doubted whether this species is native in North America. However, the small form found in the United States resembles a form occurring in Brazil in similar habitats, from which area it may have been introduced by birds. Similar disjunctions between Brazil and southeast North America are also found in C. surinamensis, C. carolinae and C. angustiretis, which all conspicuously grow together on bare, acid, white sand. Campylopus pyriformis was also found mixed with C. surinamensis, but can be distinguished by the more elongate, narrowly lanceolate leaves with a channelled apex, a long-excurrent nerve and a lamina ending at mid leaf and colorless rhizoidal tubers instead of the reddish or reddish brown ones as in C. surinamensis.
"um" is not declared as a valid unit of measurement for this property.