Weissia controversa, photographed by Des Callaghan.

Belongs within: Pottiaceae.

Weissia is a cosmopolitan genus of mostly soil-growing mosses. Most species of Weissia have sharply inflexed distal leaf margins, with a tendency to show adaxially bulging cells in leaf section; however, distinctions between Weissia and related genera such as Trichostomum are not always straightforward (R. H. Zander).

Characters (from R. H. Zander): Plants in low cushions or turfs or loosely caespitose, green above, brown to tan or yellow below. Stems to 1 cm, hyalodermis weakly differentiated to distinct, seldom absent, sclerodermis weakly differentiated in 1-2 layers, central strand present; axillary hairs with proximal 1-2 cells somewhat thicker walled. Leaves incurved, commonly tubulose and often contorted or spiraled when dry, spreading when moist; long-ligulate, oblong or triangular to long-lanceolate, 1.5-2.5(-4) mm; adaxial surface broadly channeled across leaf; base scarcely differentiated to ovate or rectangular, occasionally half-sheathing; distal margins usually sharply incurved, occasionally merely erect, seldom plane, entire; apex sharply acute to subulate, occasionally broadly acute, obtuse, or weakly cucullate; costa shortly and sharply mucronate, adaxial outgrowths absent, adaxial cells quadrate to short-rectangular except occasionally elongate near apex, in 4-8 rows; transverse section ovate, occasionally circular or semicircular, adaxial epidermis present, adaxial stereid band present, guide cells 4-6(-8) in 1 layer, hydroid strand absent, abaxial stereid band present, crescent in sectional shape, abaxial epidermis present or occasionally absent; basal cells differentiated across leaf, rarely rising higher along margins in a V, rectangular, occasionally rhomboid, 2-5:1; distal medial cells subquadrate to hexagonal, 7-13 μm, papillae 2-fid, 2-6 per lumen, occasionally fused into a large multiplex papilla covering the lumen, occasionally spiculiform and branching. Specialized asexual reproduction rare, as rhizoidal gemmae. Sexual condition monoicous (usually autoicous), occasionally dioicous; perichaetia terminal, interior leaves occasionally sheathing seta, little different from cauline leaves or somewhat larger. Seta 0.1-1.3 cm. Capsule stegocarpic or cleistocarpic; theca elliptical to short-ovate or cylindric, 1-2.2 mm, annulus in ca. 2 rows of persistent, vesiculose cells or not differentiated; operculum when present conic to rostrate; peristome teeth 16 or rudimentary or absent, occasionally removed with operculum, oblong-truncate to long-triangular, often irregularly cleft, straight or twisted weakly counterclockwise, mouth occasionally closed by a remnant of the spore sac. Calyptra cucullate. Spores 14-28 μm. KOH laminal color reaction yellow.

<==Weissia Hedw. 1801 [incl. Hymenostomum Brown 1819] SK02
    |--W. alianuda Tan 1992 [incl. Pottia nuda Mitt. ex Muell. 1880 (n. n.), W. nuda Mitt. 1882 (preoc.)] SK02
    |--W. balansae (Müll.Hal.) Zander 1993 [=Phasconica balansae Müll.Hal. 1882] SK02
    |--W. brachycarpa (Nees & Hornsch.) Jur. 1882 (see below for synonymy) SK02
    |--‘Hymenostomum’ castaneum J87
    |--W. controversa Hedw. 1801 (see below for synonymy) SK02
    |--W. edentula Mitt. 1859 [incl. W. pimpanae Müll.Hal. ex Kindb. 1889 (n. n.)] SK02
    |--W. jamaicensis J87
    |--W. novae-valesiae (Broth. ex Roth) Stone 1980 [=Astomum novae-valesiae] SK02
    |--‘Hymenostomum’ olivaceum Müll.Hal. ex Geh. 1897 [incl. H. robustum] SK02
    |--W. patula (Knight) Fife 1995 (see below for synonymy) SK02
    |--W. perpusilla (Müll.Hal.) Stone 1980 [=Phascum perpusillum, Astomum perpusillum, Hymenostomum perpusillum] SK02
    |--W. platystegia (Dixon) Eddy 1990 [=Astomum platystegium Dixon 1942] SK02
    |--W. rutilans (Hedw.) Lindb. 1863 [incl. W. muelleri (n. n.)] SK02
    |--‘Hymenostomum’ sullivanii Müll.Hal. ex Geh. 1897 SK02
    |--‘Hymenostomum’ tortile (Schwägr.) Bruch & Schimp. 1846 [incl. Weissia condensa] SK02
    `--W. willisiana (Sainsbury) Catches. 1980 [=Pottia willisiana] SK02

Nomina nuda: Hymenostomum amoenum Geh. ex Watts & Whitel. 1902 SK02
             Hymenostomum angustatum Broth. ex Watts & Whitel. 1902 SK02
             Hymenostomum pertortile Müll.Hal. ex Paris 1900 SK02
             Hymenostomum subolivaceum Müll.Hal. ex Watts & Whitel. 1902 SK02
             Weissia angustifolia Müll.Hal. ex Bailey 1890 SK02
             Weissia viridula f. eperistomata Hendey & Prent. 1970 SK02
             Weissia flavipes var. longifolia Broth. ex Watts & Whitel. 1902 SK02
             Weissia glauca Broth. ex Burges 1932 SK02
             Weissia graciliseta Broth. ex Bailey 1891 SK02
             Weissia perlinearis Müll.Hal. ex Bailey 1891 SK02
             Weissia squarrosa Broth. ex Bailey 1890 [=Hyophila squarrosa Broth. ex Watts & Whitel. 1902] SK02
             Weissia tenera Broth. ex Bailey 1891 [=Hyophila tenera Broth. ex Watts & Whitel. 1902] SK02

Weissia brachycarpa (Nees & Hornsch.) Jur. 1882 [=Hymenostomum microstomum var. brachycarpum (Nees & Hornsch.) Huebener 1833, W. microstoma var. brachycarpa] SK02

Weissia controversa Hedw. 1801 [incl. Weissia flavipes, Hyophila inflexa, Weissia nudiflora var. major Hampe 1856 (n. n.), Webera nudiflora var. major (n. n.), Weissia niflora, Bryum nudiflorum, Webera nudiflora (nom. inv.), Weissia riparia, Dicranoweisia riparia, Weissia tortelloides Broth. ex Watts & Whitel. 1902, Weissia truncata Müll.Hal. ex Watts & Whitel. 1902 (n. n.), Weissia viridula (nom. illeg.), Weissia weymouthii (preoc.), Weissia whiteleggeana Müll.Hal. ex Watts & Whitel. 1902 (n. n.)] SK02

Weissia patula (Knight) Fife 1995 [incl. W. viridula var. gymnostoma, W. controversa var. gymnostoma (Dixon) Sainsbury 1955, Gymnostomum inflexum, Hymenostomum inflexum Hampe & Müll.Hal. 1880 (n. n.), Pottia inflexa, Weissia inflexa] SK02

*Type species of generic name indicated


[J87] Judd, W. S. 1987. Floristic study of Morne La Visite and Pic Macaya National Parks, Haiti. Bulletin of the Florida State Museum – Biological Sciences 32 (1): 1-136.

[SK02] Streimann, H., & N. Klazenga. 2002. Catalogue of Australian Mosses. Flora of Australia Supplementary Series 17. Australian Biological Resources Study: Canberra.

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