PALUSTRIELLA Ochyra, J. Hattori Bot. Lab. 67: 223. 1989 * [diminutive of Latin palustris, swampy, marshy]
Plants medium-sized to robust, often stiff, green, yellow-green or brownish yellow. Stem pinnately or irregularly branched (outside North America sometimes densely branched and feather-like), with or without weak central strand and without a hyalodermis; paraphyllia present, linear to lanceolate-linear, spread on stem or often in ± transverse bands; rhizoids or rhizoid initials only on stem or at abaxial leaf costa insertion, at least partly warty-papillose, strongly branched (often forming tomentum); axillary hairs with 2--6 distal hyaline cells. Stem leaves falcate or straight, ovate or triangular-ovate, gradually narrowed to long or more rarely short acumen, plicate or strongly so, concave; marginal lamina cells 1-stratose, margin plane or sometimes reflexed at leaf base, distinctly denticulate usually only proximally (in North America); costa strong, ending in leaf apex, in weak modifications sometimes weaker and shorter; median lamina cells linear or in basal part occasionally rectangular, at least some more basal cells (beyond alar cells) usually prorate abaxially; differentiated alar cells numerous, shortly to longly rectangular, hyaline or early yellow, thin-walled or slightly incrassate, inflated, usually forming a well differentiated transversely triangular or narrowly transversely triangular group that reaches from leaf margin to costa or almost so, ± decurrent. Sexual condition dioicous. Inner perichaetial leaves gradually narrowed to acuminate apex, plicate; margin denticulate above [sometimes with scattered cilia]; lamina cells smooth. Capsule cylindric, curved and horizontal; peristome perfect; exostome margin dentate above. Spores 10.5--23 \um.
Species 3 (1 in the flora): widely distributed in the
Holarctic region, North America, Eurasia, n
Palustriella species occur in more or less strongly calcareous wetland habitats that are at least periodically influenced by springs or otherwise moving water. Palustriella species are easily recognizable by their usually strongly plicate leaves and the presence of linear to lanceolate-linear paraphyllia. They differ from Cratoneuron filicinum in having a much weaker (sometimes lacking) central strand in the stem, in having plicate rather than smooth leaves with prorate or papillose instead of smooth cells in their basal lamina, in the linear to lanceolate-linear rather than lanceolate paraphyllia, in the warty-papillose instead of smooth rhizoids, their well developed axillary hairs, and in having the exostome border much less widened at the transition zone.
1. Palustriella falcata (Bridel) Hedenäs, Bryophytorum Bibliotheca 44: 136. 1992
Hypnum falcatum Bridel, Musc. Rec. 2(3): 63. 1801; Cratoneuron falcatum (Bridel) G. Roth; C. commutatum var. falcatum (Bridel) Mönkemeyer; C. commutatum var. sulcatum (Lindberg) Mönkemeyer; C. williamsii Grout; C. falcatum var. williamsii (Grout) Flowers.
Plants mostly rather coarse, green, yellow-green or yellow-brown. Stem sparsely pinnately or irregularly branched; paraphyllia few or numerous. Stem leaves strongly falcate to ± straight, from ovate or triangular-ovate base gradually narrowed to long or more rarely short acumen, plicate or strongly so; margins usually distinctly denticulate only proximally; mostly at least some more basal median lamina cells abaxially prorate, rarely single cells with papillae; alar cells inflated, hyaline when young, becoming yellow early, forming a transversely triangular group not expanded in its marginal part. Branch leaves smaller than stem leaves, differing only slightly in shape.
Calcium-rich habitats, springs, shores, irrigated rocks, calcareous habitats; low to high elevations; Greenland, Alta., B.C., Nfld., N.W.T., Ont., Que., Yukon, Alaska, Col., Idaho, Ind., Mich., Mont., Nev., N.Mex., N.Y., Oreg., S.Dak., Tenn., Utah, Vt., Wash., Wyo.; Eurasia, n Africa, Atlantic Islands.
Palustriella falcata is widespread in the northwest, seemingly somewhat less common
in the northeast, and is absent in the northern-central and high-Arctic
areas. It has been misunderstood in
Palustriella falcata is sometimes confused with other falcate-leafed wetland species, especially with Hamatocaulis vernicosus or Sanionia uncinata, which both have plicate stem leaves. However, P. falcata has paraphyllia, and all species of Drepanocladus, Hamatocaulis, Pseudocalliergon, Sanionia, Scorpidium, or Warnstorfia that could possibly be confused with this species lack paraphyllia.