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Published In: Linnaea 13: 42. 1839. (Linnaea) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 4/12/2011)
Acceptance : Accepted
Project data     (Last Modified On 4/12/2011)
Discussion:

Leucobryum is distinguished from Octoblepharum by its channeled leaves and quadrangular chlorocysts and from Leucophanes by its lack of costal stereids. Ochrobryum has a bizarre sporophyte and mitrate calyptrae, but has been chronically confused with Leucobryum in the absence of sporophytes. The combination of its small size, single layer of dorsal and ventral leucocysts, and upper chlorocysts subdivided to form chains of rounded to quadrate cells distinguish Ochrobryum from all species of Leucobryum except L. subobtusifolium. Vegetatively the two differ differ only in the presence of bud-like propagula in Ochrobryum.

Leaf size, shape, and stature are important taxonomic characters in Leucobryum, as are characters found in the reduced leaf lamina and the number of leucocyst layers at the base of the leaves. In determining the leucocyst-layer number it is necessary to make leaf cross sections at the extreme leaf base. The glaucous green to whitish color of the plants makes the use of a contrast enhancing stain (e.g., crystal-violet) helpful.

There are eight species of Leucobryum in Central America. One (L. antillarum) is widely distributed. The others form two distributional groups, a predominately northern (Belize, Guatemala, Honduras, and Nicaragua) group and a southern (Panama and Costa Rica) group.


 

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Leucobryum Hampe, Flora 20: 282. 1837.

Plants in compact or loose cushions or mats; stems simple or forked to irregularly branched, 1–20 cm high; central strand of small, thin-walled, frequently fugacious cells; rhizoids red-brown, on stems and from apex of leaves. Leaves appressed, imbricate, elliptic-ovate at base, erect-spreading, straight or flexuous, subtubulose, at times falcate-secund above, consisting mostly of a broad costa; apex acute or obtuse and cucullate; margins incurved above, entire, or weakly denticulate at the apex; cross section at base with a median row of small, green quadangular cells (chlorocysts) enclosed by 2–8 layers of enlarged, hyaline cells (leucocysts); leaf lamina present from leaf base to midleaf, consisting of a narrow (2–12 rows of cells) marginal band of hyaline, linear, long-rectangular, short-rectangular or quadrate, variably porose, firm- to lax-walled cells. Asexual reproduction by apical clusters of reduced, deciduous leaves. Pseudautoicous; male plants minute, growing on tufts of tomentum or leaves of female plants. Perichaetial leaves at times differentiated and shortly sheathing. Setae elongate; capsules cylindrical, curved or rarely erect, commonly strumose, ribbed or smooth when dry; stomata absent; annuli mostly nonrevoluble; peristome teeth divided 1/2 the distance to the base, vertically-striate, papillose or smooth on outer surface. Calyptrae cucullate, entire.

 

 

 
 
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