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Published In: Species Muscorum Frondosorum 171. 1801. (Sp. Musc. Frond.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 2/22/2011)
Acceptance : Accepted
Project data     (Last Modified On 2/22/2011)
Discussion:

The genus Pohlia usually has a well-developed, double peristome with non-appendiculate cilia. Its leaves are lanceolate to ovate-lanceolate, have long leaf cells, unbordered margins that are usually serrate to serrulate above, and strong, single costae that are generally subpercurrent to percurrent and only occasionally shortly excurrent. There are three distinct groups within Pohlia: subg. Pohlia, subg. Nyholmiella Shaw, and subg. Cacodon Lindb. (Shaw 1984a).

Subgenus Pohlia is mostly a Northern Hemispheric group. Plants in this subgenus generally lack axillary gemmae, their capsules have elongate to rectangular, straight-walled exothecial cells, superficial stomata, and compound, revoluble annuli. Their peristomes are generally well-developed with reddish orange to brownish exostome teeth that are bordered, strongly trabeculate, and coarsely papillose above, but finely papillose below. The endostome basal membranes in subg. Pohlia can be low or high, but the segments are generally broad, keeled, and variously perforate, and the cilia vary from long and nodose to short and rudimentary.

Subgenus Nyholmiella is mostly a Southern Hemispheric group. Plants in this subgenus often have axillary gemmae, capsules with rectangular to isodiametric, straight-walled or sinuose (often bulging) exothecial cells, superficial or sunken stomata, and compound annuli. Their peristomes are usually reduced with white to whitish yellow, narrow exostome teeth that are not bordered, weakly trabeculate, and densely, evenly papillose throughout. The endostome basal membranes in subg. Nyholmiella can be low or high, but the segments are linear, flat or weakly keeled, and not or weakly perforate, and the cilia are absent or rarely rudimentary.

Subgenus Cacodon includes those species which have in the past been treated in the segregate genus Mniobryum B.& S. ex Limpr. Plants in this subgenus frequently have axillary gemmae or rhizoidal tubers, capsules with short rectangular to isodiametric, strongly sinuose exothecial cells, superficial or immersed stomata, and poorly developed, non-revoluble annuli. Their peristomes are well-developed with reddish orange to brownish exostome teeth that are bordered, strongly trabeculate, and coarsely papillose above but finely papillose below. The endostome basal membranes in this subgenus can be low or high, but the segments are broad, keeled, and widely perforate, and the cilia are long and nodose.

Pohlia grades into Bryum in nearly every feature and there are some Bryum species (e.g., B. apiculatum) that occasionally are treated in Pohlia. As a result of this morphological intergradation Pohlia can only be distinguished from Bryum by a suite of characters that include long, narrow, unbordered leaves, long, narrow leaf cells, costae percurrent (or just barely excurrent), and nodose endostomial cilia (although P. nutans can have appendiculate cilia). Remarkably, Buck & Goffinet (2000) placed these very similar genera in different families (Bryum, Bryaceae; Pohlia, Mniaceae). As noted by Shaw (1994) when sporophytes are absent the genera Pseudopohlia, Mielichhoferia and Schizymenium cannot be distinguish from Pohlia without prior experience with the individual species.

Shaw (1982a) revised the genus Pohlia in North and Central America and the West Indies.


 

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Pohlia Hedw., Sp. Musc. Frond. 171. 1801. 

Plants small to robust, glossy or dull, in erect, loose tufts. Stems, simple or sparsely and irregularly branched; rhizoids reddish orange to brownish, papillose, sometimes with tubers. Leaves close or distantly spaced, erect to erect-spreading, lanceolate to ovate-lanceolate, weakly to strongly decurrent; apices acute or rounded at the apex; margins plane or narrowly recurved above, serrate to serrulate, rarely entire near apex, entire to serrulate below; costa single, percurrent to excurrent; cells smooth, thin- or thick-walled, upper cells long-hexagonal to linear, basal cells rhomboidal, alar cells rectangular to quadrate. Propagula occasionally in leaf axils. Dioicous or paroicous. Setae elongate, straight, 1 or more per perichaetium. Capsules inclined to erect; exothecial cells isodiametric to elongate with straight or sinuose walls; stomata superficial or immersed; opercula conic, acute to apiculate, rarely rostrate; annuli well-developed or rudimentary; peristome diplolepidous, exostome teeth 16, papillose, trabeculae strongly or weakly developed, endostome perfect or imperfect, basal membrane low or high, segments broad, keeled and widely perforate to narrow, flat and entire, cilia long and nodose (rarely appendiculate), rudimentary or absent. Spores papillose. Calyptrae cucullate, smooth.

 

 
 
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