Tropicos | Name - !!Atrichum P. Beauv.

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!!Atrichum P. Beauv.

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Project Name Data (Last Modified On 9/25/2009)

Acceptance : Accepted

Project Data (Last Modified On 8/6/2022)

Plant Category: Mosses

General Reference:

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

Notes (Last Modified On 8/6/2022)

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 in shaded sites, 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 Andes tropiales el género está representado por dos especies. 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.

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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.