Leucobryum albidum Lindberg 1863

Leucobryum albidum characteristically occurs in small, low cushions, usually no more than 10 cm in diameter, and frequently bears sporophytes. Of the 1035 collections examined, 632 (61 percent) had sporophytes. Leucobryum albidum is sometimes difficult to separate from small plants of L. glaucum. Some authors have used the number of leucocysts, as seen in transverse section, on both sides of the chlorocyst layer on thicker, lateral regions of costa to separate these species. However, this character varies widely on plants from the same colony and even on different sides of the same leaf. There is also no consistent pattern for these species across the geographical range, and correlation with other characters such as stem height and length of limb to length of sheath is inconclusive. The most satisfactory criteria for recognizing L. albidum are its generally compact, short cushions and leaves 2-4 mm with reflexed limb usually shorter than the sheath. E. Patterson et al. (1998) in a study of Leucobryum from a limited area near Durham, North Carolina, using nuclear ribosomal DNA extracts from plants of various sizes, demonstrated that two haplotyes were present, and that L. albidum (small plants) is genetically discontinuous with L. glaucum (large plants). Leucobryum incurvifolium Müller Hal. [= Terrestria incurvifolia ( Müller Hal.) W. L. Peterson] was reported from Florida (W. L. Peterson and A. J. Sharp 1980). However, the two collections cited from Florida appear to be nothing more than a variation of L. albidum. They do not have the distinct cucullate, hyaline-apiculate leaf tips characteristic of L. incurvifolium (Peterson 1994).

Plants in low, compact cushions or turfs. Stems less than 1 cm tall (rarely to 4.5 cm). Leaves 2-4(-6) mm, limb subtubulose, erect to wide-spreading, straight, apex apiculate, entire, speading from oblong-obovate sheath, shorter than (rarely equal to) the length of the sheath; costa in transverse section near base showing lateral, thicker regions composed mostly of 2(-3) layers of enlarged leucocysts on both sides of the central layer of chlorocysts, and a central, thinner region composed of 1 layer of smaller leucocysts on both sides of the chlorocyst layer; lamina narrow, 8-11 cells wide. Specialized asexual reproduction by small leaf-like gemmae on minute, forked branches at stem tip or on pseudopodium-like branches and by caducous leaves with rhizoids at leaf apex. Seta 8-12 mm, brown to reddish. Capsule strongly inclined and curved when dry and empty, sometimes slightly strumose, 1.2-1.8 mm, red to reddish brown; operculum 1-1.3 mm; peristome teeth dark red. Spores minutely papillose, 11-16 µm.

Dicranum albidum P. Beauvois, Prodr. Aethéogam., 52. 1805

Leucobryum albidum (Brid.) Lindb. Oefv. Sv. Vet.-Akad
Forh. 20: 403. 1863;
1
Dicranum albidum Brid. Muse. Recent. 2 1 : 167. 1798. Dicranum glaucum pumilum Michx. Fl. Bor. Am. 2: 297. 1803. Dicranum glaucum albidum Brid. Bryol. Univ. 1: 409. 1826. Leucocobryum vulgare minus Hampe, Linnaea 13: 42. 1839. Leucobryum sediforme C. Mull. Syn. 1: 75. 1848.
Leucobryum minus Hampe; Sull. in A. Gray, Man. ed. 2. 624. 1856. Leucobryum pumilum EG. Britton, Bull. Torrey Club 19: 190. 1892; Leucobryum incurvifolium C. Mull. Bull. Herb. Boiss. 5: 174. 1897. — Leucobryum glaucum albidum Card. Rev. Bryol. 38: 80. 1911.
Pseudautoicous: male plants 1-3 mm. high, on tomentum enclosed by old perichaetial leaves of sterile archegonia; flowers with 2 or 3 antheridia about 0.25 mm. high, without paraphyses, surrounded by 4 or 5 lanceolate-pointed leaves from a somewhat broader, concave base: fertile plants in compact cushions, with branching stems up to 3 cm. high, bearing crowded leaves erect-appressed or widely spreading at the tips: stem-leaves 2-4.5 mm. long, from an ovate base narrowed to a subtubulose point usually scarcely as long as or often much shorter than the base; costa in cross-¥ection"near the base showing 2 layers of cells above and PART 2, 1913] LEUCOBRYACEAE 165
2 layers below the chlorocysts in the thicker parts and 1 layer on either side near the middle of the costa; perichaetial buds mostly appearing terminal and solitary, the inner perichaetial leaves longer and projecting well above the stem-leaves: seta red, erect, 12-18 mm. long: capsule about 1.5 mm. long, nodding, scarcely or not strumose or rarely distinctly strumose, when dry curved and furrowed, without stoma ta; annulus wanting ; lid rostrate, about as long as the capsule; peristome-teeth divided about one half down: spores rough, up to 16 m in diameter.
/ Type locality: Virginia. ^
t Distribution ^New Jersey to Ohio, and southward to Florida and Louisiana/ Cubs*: Andros
Bahamas; Mexico/Guatemala. -■—— — ^^___-^

Leucobryum albidum (common name Pincushion Moss) is a species of moss with a wide distribution in the northern and southern hemispheres. This plant first appeared in scientific literature as Dicranum albidum in 1805 published by the French naturalist Palisot de Beauvois.

Leucobryum albidum là một loài Rêu trong họ Dicranaceae. Loài này được (Brid. ex P. Beauv.) Lindb. mô tả khoa học đầu tiên năm 1863.