Tropicos | Name - !!Atrichum P. Beauv.

Bolivia Bryophytes > Polytrichaceae > Atrichum

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!!Atrichum P. Beauv.

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Project Name Data (Last Modified On 4/30/2009)

Acceptance : Accepted

Project Data (Last Modified On 10/30/2017)

Plant Category: Moss

Notes (Last Modified On 10/30/2017)

general taxon notes:

Atrichum contains some 20 species of temperate regions, particularly the Northern Hemisphere; four species in the Neotropics. Premontane to mid montane regions, often associated with forest margins or open forest in the Tropical Andes; on soil, frequently found near or along streams. The genus is characterized by the crispate and contorted leaves when dry, not or weakly differentiated leaf base, narrow costa, 4-6 rows of lamellae, doubly toothed and bordered margins, and 32 peristome teeth. The only other genus likely to be confused with Atrichum is Steereobryon - the latter is readily differentiated by the finely pluripapillose and bluntly, single toothed margins.

Atrichum contiene unas 20 especies de regiones templadas, particularmente del hemisferio norte; cuatro especies han sido registradas en el Neotrópico. En Bolivia el género está representado sólo por una especie, Atrichum polycarpum (Müll. Hal.) Mitt. Este género se caracteriza por las hojas crispas y contortas cuando secas, base de la hoja débilmente diferenciado o no, costa angosta, 4-6 filas de lamelas, márgenes bordeados y doblemente dentados y 32 dientes del peristoma. El único género que puede ser confundido con Atrichum es Steereobryon; este último se diferencia fácilmente por los márgenes finamente y claramente pluripapilosos, con dientes simples.

Reference List (Last Modified On 10/30/2017)

Reference:

Nyholm, E. 1971. Studies in the genus Atrichum P. Beauv. A short survey of the genus and species. Lindbergia 1: 1–33.

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Plants medium sized to somewhat large, forming loose tufts, dark green to blackish-green or -brown. Stems erect, simple to few branched; central strand well-developed; radiculose, rhizoids reddish-brown or pale white. Leaves crispate, oblong-lanceolate, often weakly to strongly undulate, usually toothed on back of lamina and costa, apex acute to short acuminate, base weakly sheathing; margins plane, limbate, doubly-toothed; costae single, narrow, percurrent, in cross-section with stereid bands above and below guide cells; laminal cells oblong-short rectangular to subquadrate, thick-walled; basal cells rectangular, thick-walled; margins cells elongate; lamellae confined to costa, in few rows, 3-6 cells high, terminal cells rounded. Dioicous or autoicous. Perichaetia terminal; leaves differentiated. Setae 1-3(4), elongate, smooth. Capsules suberect to inclined, urn cylindrical, asymmetric, slightly to somewhat strongly curved; exothecial cells rectangular, thick-walled; opercula conic long-rostrate, oblique; peristome single, teeth 32. Calyptrae cucullate, roughened distally. Spores papillose.

Plantas medianas hasta algo grandes, formando manojos laxos, verde oscuras hasta verde-negruzcas o -pardas. Tallos erectos, simples hasta poco ramificados; cordón central bien desarrollada; radiculoso, rizoides pardo-rojizos o blancos pálidos. Hojas crispas, oblongo-lanceoladas, a menudo débilmente a marcadamente undulada, lámina y costa generalmente dentadas en el envés, ápices agudos hasta corto-acuminados, bases débilmente envainadoras; márgenes planos, limbados, doblemente dentados; costa simple, angosta, percurrente, en corte transversal con bandas de estereidas encima y debajo de las células guía; células de la lámina corto-oblongas rectangulares hasta subcuadradas, con paredes gruesas; células basales rectangulares, con paredes gruesas; células de los márgenes alargadas; lamelas confinadas a la costa, en pocas filas, 3-6 células de alto, células terminales redondeadas. Dioicas o autoicas. Periquecios terminales; hojas diferenciadas. Setas 1-3(4), alargadas, lisas. Cápsulas suberectas hasta inclinadas, urna cilíndrica, asimétricas, escasamente hasta algo marcadamente curvadas; células exoteciales rectangulares, con paredes gruesas; opérculos cónico largo-rostrados, oblicuos; peristoma simple, con 32 dientes. Caliptra cuculada, distalmente rugosa. Esporas papilosas.