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Published In: Linnaea 32(2): 154. 1863. (Linnaea) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 9/27/2009)
Acceptance : Accepted
Project Data     (Last Modified On 10/8/2017)
Plant Category: Mosses

Notes     (Last Modified On 10/8/2017)

Porotrichum, including Porothamnium, contains far fewer than the stated 80 or more species. The genus is pantropical in distribution; about 10-15 species in the Neotropics. Additional studies are required of taxa described from the central tropical Andes, particularly Bolivia and northwest Argentina. Porotrichum is commonly encountered from premontane to high montane forest, rare in moist lowland forest adjacent to the highlands in the tropical Andes. Species are commonly epiphytic, on branches and trunk of trees and treelets, less frequent on logs and rocks. The genus is characterized by the frondose habit, short to long stipes bearing scale-like leaves, mostly irregularly pinnate with complanate-foliate branches, mostly symmetric leaves, marginal serrations of 1-2 cells, slender costa 1/2-3/4 leaf length, and elongate rhomboidal to fusiform apical cells. Sporophytes are not infrequent, however the primary means of reproduction and dispersion is by the rather fragile flagellate branches that are nearly always present. Several of our species were previously placed in the genus Porothamnium.


Porotrichum, incluyendo Porothamnium, contiene menos de las 80 o más especies establecidas. El género tiene distribución pantropical; ca. 10-15 especies en el Neotrópico. Estudios adicionales son requeridos en los taxa descritos en los Andes tropicales centrales, especialmente en Bolivia y noroeste de Argentina. Este género se caracteriza por el hábito frondoso, estípites cortos hasta largos con hojas escuamiformes, por lo general irregularmente pinnados con ramas complanado-foliosas, hojas generalmente simétricas, bordes serrados formados por 1-2 células, costa delgada ocupando 1/2-3/4 de la longitud de la hoja y células apicales alargadas rómbicas hasta fusiformes. Los esporofitos no son poco frecuentes, sin embargo, el principal medio de reproducción y dispersión es a través de las ramas flageladas bastante frágiles que están casi siempre presentes


Status unknown or excluded:

Porothamnium gracile Broth., Rev. Bryol. 47: 16. 1920. Type: Ecuador. Prov. del Oriente, secusviam ad rivum Bomboiza, 850 m, Allioni.


Porothamnium valdiviae (Müll. Hal.) M. Fleisch., Nat. Pflanzenfam. (ed. 2) 11: 200. 1925. Hypnum valdiviae Müll. Hal.,Bot. Zeitung (Berlin) 13: 783. 1855. Type: Chile. Reported for Peru; considered doubtful.


Porotrichum bolivianum Müll. Hal. ex E. Britton, Bull. Torrey Bot. Club 23: 496. 1896. Thamnium scoposum subsp. bolivianum (Müll. Hal. ex E. Britton) Kindb., Hedwigia 41: 244. 1902. Type: Bolivia. Near Yungas, 4000 ft., 1885, Rusby 3174.


Porotrichum lorentzii Müll. Hal., Linnaea 42: 406. 1879. Porothamnium lorentzii (Müll. Hal.) M. Fleisch., Musci Buitenzorg 3: 927. 1908. Type: Argentina. Sierra de Tucumán, Siambon, fine Januarii 1874, Lorentz; Cuesta de Buyuyu, inter Orthostichellam, 15 Junio 1873, Lorentz; ad lapides infauce montosa prope Juntas, fine Decembris 1972, Lorentz; Rio seco prope Sn. Andrés, 16 Junio 1873, Lorentz.


? = Porothamnium neckeraeforme (Hampe) M. Fleisch. Nat. Pflanzenfam. (ed. 2) 11: 199. 1925. Hypnum neckeraeforme Hampe, Ann. Sci. Nat., Bot. 5, 5: 309. 1866.


Porotrichum macropoma Herzog, Biblioth. Bot. 87: 118. 45. 1916. Syntypes: Bolivia. Im Nebelwald über Comarapa, ca. 2600 m, Herzog 4312; im Bergwald des Rio Tocorani, ca. 2200 m, Herzog 4080/a.


Porotrichum microthecium Müll. Hal., Nuovo Giorn. Bot. Ital. n. s. 4: 148. 1897. Type: Bolivia. Sin. loc. & leg. Possible type data: Cochabamba, prope Choquecamata, Germain.


Porotrichum protensum Renauld & Cardot, Bull. Soc. Roy. Bot. Belgique 41(1): 84. 1905. Porothamnium protensum (Renauld & Cardot) Broth., Nat. Pflanzenfam. 1(3): 1230. 1909. Type: ? Reported for Ecuador.


Published nomen nudum:

Porothamnium subramosissimum Broth., Biblioth. Bot. 87: 119. 1916, nom. nud. Based on Herzog 4236 (JE!). Bolivia: 2200-2600 m.


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Plants medium sized to large, forming loose, rarely dense, tufts, glossy to dull green, yellowish-green or golden. Primary stems creeping, leaves scale-like or eroded, radiculose below. Secondary stems dendroid or frondose; stipe short to long, leaves clasping to squarrose; stems regularly to irregularly pinnately branched, flagelliform branches common. Secondary stem leaves erect to erect-spreading, oblong-ovate or -ligulate, apex mostly broadly acute to obtuse; margins plane to recurved, serrate in distal 3/4 or less, serration often irregular, course; costae single, 1/2-3/4 lamina length; median cells fusiform-rhomboidal to oblong-linear, smooth to papillose, papillae projecting at cell angles, variously porose throughout, or only at base; basal cells linear to rectangular; alar region undifferentiated or differentiated, cells short-rectangular or subquadrate. Branch leaves often differentiated, or progressively smaller. Dioicous. Perichaetia lateral; leaves oblong- or ovate-subulate. Setae elongate, smooth. Capsules erect to horizontal, urn cylindrical; stomata at urn base; opercula short to long rostrate; peristome double, exostome teeth 16, striate to striate-papillose below, distally papillose; endostome basal membrane high, segments 16, papillose, perforate, cilia well developed to rudimentary. Calyptrae cucullate, smooth and naked. Spores spherical, papillose.


Plantas medianas hasta grandes, formando manojos laxos, rara vez densos, verde brillantes hasta opacas, verde amarillentas o doradas. Tallos primarios reptantes, hojas escuamiformes o erosionadas, radiculosos abajo. Tallos secundarios dendroides o frondosos; estípite corto hasta largo, hojas amplectantes hasta escuarrosas; ramas de los tallos regularmente hasta irregularmente pinnadas, ramas flageladas comunes. Hojas de los tallos secundarios erectas hasta erecto-extendidas, oblongo-ovadas o -liguladas, ápices por lo general anchamente agudos hasta obtusos; márgenes planos hasta recurvados, serrados en 3/4 distales o menos, a menudo irregularmente serrado, correoso; costa simple, ocupando 1/2-3/4 de la longitud de la lámina; células mediales fusiforme-romboidales hasta oblongo-lineales, lisas hasta papilosas, papilas proyectándose en los ángulos de la célula, diversamente porosas por completo o sólo en la base; células basales lineales hasta rectangulares; región alar indiferenciada o diferenciada, células corto-rectangulares o subcuadradas. Hojas de las ramas a menudo diferenciadas, o progresivamente menores. Dioicas. Periquecios laterales; hojas oblongo- u ovado-subuladas. Setas alargadas, lisas. Cápsulas erectas hasta horizontales, urna cilíndrica; estomas en la base de la urna; opérculo corto- hasta largo-rostrado; peristoma doble, exostoma con 16 dientes, estriados hasta estriado-papilosos abajo, distalmente papilosos; membrana basal del endostoma alta, con 16 segmentos, papilosos, perforados, cilios bien desarrollados hasta rudimentarios. Caliptra cuculada, lisa y desnuda. Esporas esféricas, papilosas.


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1. Leaves at mid-stipe spreading to squarrose when dry; margins of stipe leaves recurved … 2.

1. Leaves at mid-stipe erect-appressed or erect-spreading with spreading subulae from an erect base; margins of stipe leaves plane … 5.

2. Stipe leaves mostly squarrose; branch leaves mostly orbicular … P. thielianum

2. Stipe leaves mostly spreading; branch leaves ovate-lanceolate to oblong-ligulate … 3.

3. Plants small, to 5 cm tall; branch leaves ovate-lanceolate, apex acute, costa mostly ending in a tooth … P. substriatum

3. Plants mostly more than 5 cm tall, to 10 cm tall; branch leaves ligulate to oblong, broadly acute to obtuse … 4.

4. Leaves mostly plicate when dry; margins of stem and branch leaves recurved … P. filiferum

4. Leaves mostly smooth when dry; margins of stem and branch leaves plane … P. expansum

5. Median cells of stem leaves oval (3-4: 1) … 6.

5. Median cells of stem leaves fusiform to linear (5-10: 1) … 7.

6. Leafy stems ± complanate; leaves weakly concave or not, base not auriculate … P. piniforme

6. Leafy stems ± terete; leaves deeply concave, base weakly auriculate …see Porotrichodendron lindigii

7. Stem leaves mostly ovate-ligulate to ligulate … 8.

7. Stem leaves mostly ovate-lanceolate to broadly ovate … 9.

8. Branch leaves mostly acute, serrate only at apex; upper median cells of stem leaves linear, slightly porose … P. mutabile

8. Branch leaves mostly broadly acute to obtuse, serrate in upper 1/2; upper median cells of stem leaves fusiform to long hexagonal, walls entire … P. korthalsianum

9. Branch leaves ovate-lanceolate, acute; margins serrate in upper 1/2 … P. longirostre

9. Branch leaves obovate, broadly acute to obtuse; margins serrate to leaf base … P. lancifrons



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