Paraleucobryum

(Lindberg ex Limpricht) Loeske

Allg. Bot. Z. Syst. 13: 162. 1907,.

Etymology: Greek para-, near, and genus Leucobryum, alluding to resemblance
Basionym: Dicranum subg. Paraleucobrym Lindberg ex Limpricht in G. L. Rabenhorst et al., Krypt.-Fl. ed. 2, 4(1): 373. 1886
Treatment appears in FNA Volume 27. Treatment on page 425. Mentioned on page 359, 426, 427, 440.

Plants in loose to dense tufts, whitish green, grayish green or yellowish green, glossy. Stems 1–4 cm, erect, simple or branched, rhizoids on stems below apex among leaves. Leaves subulate to narrowly lanceolate, gradually acuminate, subtubulose distally, erect-spreading to falcate-secund, especially at stem tips, little changed when dry, smooth; apices acute, sometimes deciduous; margins plane or incurved, serrate to serrulate distally to below leaf middle; laminae unistratose; costa single, percurrent, covering 1/2–2/3 of leaf base and all of subula, smooth or striate on abaxial surface, absent stereids, composed of 3–4 layers of large cells, hyaline, nonchlorophyllose cells intermingled with green, chlorophyllose cells, striations or ridges appearing as rows of teeth at high magnifications on abaxial surface of costa (P. longifolium); leaf cells pitted proximally, smooth, walls of medium thickness, median cells quadrate to rectangular, elongate proximally, alar cells inflated, extending to costa, 1-stratose, brown or sometimes hyaline. Specialized asexual propagation absent. Sexual condition dioicous; perigonia and perichaetia terminal; perigonial leaves ovate, concave, short-acuminate; perichaetial leaves with a broad base, abruptly narrowed to a long awn, inner ones sheathing. Seta solitary or rarely 2 per perichaetium, smooth, elongate, erect, straight to flexuose, twisted when dry, yellowish-brown. Capsule erect to somewhat inclined, cylindric, straight, smooth, irregularly furrowed when dry, a few stomata at base, exothecial walls incrassate; annulus rudimentary; operculum rostrate, straight; peristome single, 16 lanceolate teeth, divided about halfway into 2 segments, papillose above, vertically to obliquely striate below, brown to reddish-brown. Spores 22–33 µm, spherical to ellipsoidal, minutely papillose. Calyptra cucullate, smooth, naked, covering most of capsule, fugacious.

Distribution

North America, Mexico, Europe, Asia

Discussion

Species 3 or 4 (2 in the flora).

Paraleucobryum is a rather peculiar member of the Dicranaceae because of its unique leaf structure. In the leaf cross section there is an adaxial and abaxial layer of hyalocysts and a median layer of chlorocysts. Sometimes a few chlorocysts are in the abaxial layer of cells in some species. Brothera and Atractylocarpus have a very similar leaf structure and are the reason that the three genera are often placed in the same subfamily, Paraleucobryoideae. Both B. H. Allen (1999) and P. Müller and J.-P. Frahm (1987) presented extensive discussion on the relationship of Paraleucobryum to other members of the Dicranaceae. They also discuss what may be heterospory or bimodal spores in P. longifolium.

Key

1 Costa with longitudinal striations, formed by rows of teeth evident at high magnifications, on abaxial surface (especially conspicuous in distal half); leaf margins serrulate near apex. Paraleucobryum longifolium
1 Costa smooth on abaxial surface; leaf margins entire or rarely with a few teeth at apex. Paraleucobryum enerve
... more about "Paraleucobryum"
persistent +  and deciduous +
deciduous +
Robert R. Ireland Jr. +
(Lindberg ex Limpricht) Loeske +
short to long +
Dicranum subg. Paraleucobrym +
microphyllous +
pseudomonoicous +, dioicous +, autoicous +  and sexual +
reproduction +  and asexual +
cucullate +
inclined +  and erect to somewhat +
cylindric +
hyaline +, brown +  and green +
specialized +
3 (?) +  and 4 (?) +
papillose +  and mammillose +
dioicous +, sexual +  and asexual +
inflated +
percurrent;excurrent +
North America +, Mexico +, Europe +  and Asia +
Greek para-, near, and genus Leucobryum, alluding to resemblance +
falcate-secund +
acuminate +, subulate +  and narrowly lanceolate +
serrate +  and serrulate +
nonpitted +  and pitted +
toothed +  and forked +
short-acuminate +, concave +  and ovate +
brown +  and reddish-brown +
16 +  and single +
undifferentiated +
Allg. Bot. Z. Syst. +
allen1999a +, barnes1958a +  and ireland1994b +
yellowish-brown +
straight +  and flexuose +
elongate +
spherical +  and ellipsoidal +
branched;simple +
1 cm10 mm <br />0.01 m <br /> (4 cm40 mm <br />0.04 m <br />) +
superficial +
Paraleucobryum +
Dicranaceae +
deciduous +
lanceolate +
yellowish green +, grayish green +  and whitish green +