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Published In: Bryologia Europaea 3: 93 (fasc. 25–28 Monogr. 1). 1845. (Bryol. Eur.) Name publication detail
 

Project Name Data (Last Modified On 2/17/2011)
Acceptance : Accepted
Project data     (Last Modified On 2/17/2011)
Discussion:

Schistidium is a genus of small, dark‑green plants nearly always found on bare rock. The genus typically has short, erect (sometimes hyaline‑pointed) leaves, short, broad, immersed capsules and well‑formed, haplolepidous peristome teeth. Schistidium and Grimmia have identical gametophytes and are sometimes treated as a single genus. Schistidium differs from Grimmia in having systylius capsules, greatly enlarged perichaetial leaves and poorly developed stomata. Systylius capsules have evolved several times in the mosses but their function is unknown. Bremer (1981) suggested the feature enhanced spore dispersal by carrying large numbers of spores along with the columella when the operculum was detached. Alternatively, the advantages of this structure may lie in the fact that the capsules remain only partially open for some time after dehiscence. This may be beneficial in reducing desiccation and in limiting spore dispersal to times of more optimal conditions for the establishment and germination of spores, i.e., during the period between wetting and drying when the peristome teeth undergo hygroscopic motion.

The presence of small, non‑plicate calyptrae separate Grimmia and Schistidium from the rest of the Grimmiaceae. The calyptra can be mitrate or cucullate, but the distinctions between these two types of calyptra in Schistidium are minor and in fact both types can be found within single species or even single collections.


 

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Schistidium Bruch & Schimp. in B.S.G., Bryol. Eur. 3: 93. 1845 nom. cons. 

Plants in dark-green or blackish green tufts or cushions, mostly rupestral. Stems erect, forked or fastigiate branched, central strand present or absent; rhizoids sparse. Leaves crowded, hygroscopic, imbricate, erect‑patent, ovate‑lanceolate, plane, keeled or concave; apices gradually acute to acuminate, with or without a hyaline point; margins plane or recurved; costa single, strong, percurrent to excurrent, smooth or papillose, convex at back, mostly homogenous in cross‑section; lamina unistratose below, uni‑ to multistratose above, cells incrassate with straight or sinuose walls; upper cells mostly small and rounded‑quadrate, smooth or rarely papillose, basal cells elongate, not strongly differentiated. Dioicous or autoicous. Perichaetial leaves elongate, distinctly larger than vegetative leaves with stronger, usually excurrent costae. Setae short, straight. Capsules symmetric, immersed, erect, oblong to cylindrical, smooth or ribbed when dry; stomata present or absent; columella attached to the operculum frequently falling with it; opercula conic, apiculate to shortly erect; peristome of 16 cuneiform teeth, rarely rudimentary, entire, perforate or cribrose. Calyptrae small, just covering the capsule, mitrate or cucullate, not plicate.

 

 
 
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