BFNA Title: Palustriella
Author: L. Hedenäs
Date: July 2000
Edit Level: R
Version: 3

Bryophyte Flora of North America, Provisional Publication

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AMBLYSTEGIACEAE-- Palustriella
Edit Level R

PALUSTRIELLA Ochyra, J. Hattori Bot. Lab. 67: 223. 1989 * [diminutive of Latin palustris, swampy, marshy]

Lars Hedenäs

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 Africa.

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.

SELECTED REFERENCES Bell, P. R. and E. Lodge. 1963. The reliability of Cratoneuron commutatum (Hedw.) Roth as an 'indicator moss'. J. Ecol. 51: 113--122. Hedenäs, L. and A. Kooijman. 2004. Habitat differentiation within Palustriella. Lindbergia 29: 40--50. Ochyra, R. 1989. Animadversions on the moss genus Cratoneuron (Sull.) Spruce. J. Hattori Bot. Lab. 67: 203--242.

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., 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 North America, and most specimens identified as P. commutata (Hedwig) Ochyra, as well as the few P. decipiens (Notaris) Ochyra records, belong to this species. When well developed, P. falcata differs from both P. commutata and P. decipiens in its larger size and the more sparse and often irregular branching pattern. The stem leaves are ovate or triangular-ovate and gradually narrowed to a long and mostly falcate acumen in P. falcata, broadly cordate-triangular and mostly suddenly narrowed to a short and recurved or elongate and falcate acumen in the two other species. In P. falcata the stem and branch leaves are generally similar in shape, whereas in P. commutata and P. decipiens they differ markedly. The alar cell group is mostly strongly expanded in its marginal part in P. commutata and P. decipiens, not so in P. falcata, and the areolation of the stem leaves is usually more regular in P. falcata than in the other two. A specimen in the herbarium of the Missouri Botanical Garden, with the locality "Salem" on the label, apparently from North Carolina, belongs to P. commutata. However, because the original label information does not indicate that the Salem where the specimen was collected is in North America, its true origin is doubtful.

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.