25. DITRICHACEAE Limpricht

Rodney D. Seppelt

Plants minute or rather small to medium-sized, gregarious or loosely to densely tufted. Stems erect, simple or forked, with a central strand. Leaves mostly lanceolate, acuminate or subulate, straight or somewhat curved, rarely sheathing at base; in numerous rows (2 rows in ); costa single, well developed, subpercurrent to excurrent, in section with 1 row of guide cells and 2 stereid bands, adaxial band sometimes much reduced; lamina cells smooth (± roughened in subula in Distichium); basal cells elongate, narrower towards the margins, those of basal angles not differentiated or forming a marginal border; distal cells isodiametric or short- rectangular to elongate, walls firm. Specialized asexual reproduction occasional, as multicellular filamentous gemmae borne in axils or along stems, or as specialised tubers or filamentous propagules on rhizoids. Sexual condition dioicous, autoicous, paroicous, or synoicous; perigonia axillary or on short branches adjacent to perichaetia, or terminal on separate ; perichaetial leaves not markedly differentiated or with a longer, broader sheathing base and shorter subulate apex. Seta short to ± elongate, yellow to orange, reddish brown, brown, or reddish purple; capsules immersed to emergent and subglobose to long-exserted and ± cylindric, erect to inclined or pendulous, often ± curved or asymmetric; cleistocarpous, gymnostomous, or peristomate; annulus, when present, usually of 2–3 rows of larger cells, deciduous; peristome, when present, single, of 16 teeth, variously split into two terete filaments or perforate to near the base; operculum conic to short-rostrate. Calyptra cucullate, rarely mitrate. Spores spheric to ovoid or ± reniform, finely to coarsely papillose, verrucose, or somewhat vermicular or reticulate. Genera 25, species ca. 140 (9 genera, 25 species in the flora): cosmopolitan, greatest occurrence in temperate regions. Species of Ditrichaceae usually colonize soil, rarely wood, and some species have a distinct preference for calcareous substrates. The family is poorly defined and separated from Dicranaceae primarily on peristome characteristics, with the teeth divided into terete rather than flat filaments, and the general absence of vertical pit-striations. In some species, however, oblique ornamentation is present, at least in the distal portion of the teeth. W. R. Buck and B. Goffinet (2000) included 25 genera, with one hybrid genus, Pleuriditrichum, in the family. The inclusion of at least some of the genera seems somewhat anomalous. Within the flora, , Distichium, , , and Trichodon are peristomate, while Cleistocarpidium,

443 444 DITRICHACEAE

Eccremidium, Pleuridium, and Pseudephemerum are cleistocarpic. Although in this treatment it is included in Ditrichaceae, Pseudephemerum was placed in Dicranaceae by Buck and Goffinet.

SELECTED REFERENCE Britton, E. G. 1913b. Ditrichaceae. In: N. L. Britton et al., eds. 1905+. North American Flora.... 47+ vols. New York. Vol. 15, pp. 55–67.

1. Leaves in two rows, base ± sheathing, abruptly narrowed to a ± roughened subula ...... 2. Distichium, p. 448 1. Leaves in more than two rows. 2. Leaves glaucous blue-green ...... 4. Saelania, p. 458 2. Leaves yellow-green to green or brownish green, never glaucous blue-green. 3. Leaves squarrose from a sheathing base, subulate, the subula tubulose and strongly prorulose abaxially ...... 5. Trichodon, p. 459 3. Leaves lanceolate to subulate, the base ± sheathing or not, not squarrose. 4. Stems generally elongate, 0.5–4 cm or sometimes longer; capsule, when present, peristomate. 5. Leaves lanceolate, ovate-lanceolate or triangular-ovate to obovate, margins recurved; seta reddish purple to yellowish orange, capsule erect to inclined, strongly sulcate when dry ...... 1. Ceratodon, p. 445 5. Leaves lanceolate to subulate, margins mostly plane, occasionally weakly recurved; seta pale yellow to yellow to orange to reddish brown, capsule erect to suberect, not sulcate when dry ...... 3. Ditrichum, p. 450 4. Stems generally very short, 0.2–0.8 cm; capsule, when present, immersed and cleistocarpic. 6. Leaves loosely erect, subulate-acuminate from a lanceolate base, margins sharply serrate distal to the shoulders, costa excurrent, filling subula; seta stout, arcuate; capsule laterally emergent, pendulous ...... 7. Eccremidium, p. 461 6. Leaves erect-spreading or appressed or reflexed-recurved, oblong to lanceolate or subulate, margins plane, serrulate towards apex, costa subpercurrent to excurrent; seta short, erect to curved, not arcuate; capsule erect to inclined, not pendulous. 7. Leaves reflexed-recurved, lanceolate from an ovate base, margins plane, entire, serrulate at the flat apex; laminal cells thin-walled, proximal cells larger, rectangular, distal cells rhombic; capsule ovoid ...... 9. Pseudephemerum, p. 467 7. Leaves erect-spreading or appressed, oblong to lanceolate with subulate to acuminate tips, margins plane, entire to serrate or abruptly toothed; lamina cells quadrate-rectangular proximally, becoming irregularly rhomboid to trapezoidal and elongated distally; capsule ovoid to elliptic. 8. Stem leaves 2–4 mm, loosely erect, subulate from an ovate- lanceolate to narrowly obovate base, entire, serrulate along subula; capsule immersed, ovoid, broadest at base, whitish, spore sac orange ...... 6. Cleistocarpidium, p. 460 8. Stems leaves 0.5–2 mm, erect-spreading or appressed, imbricate to spreading, oblong to lanceolate with subulate to acuminate tips, entire to serrate or abruptly toothed; capsule immersed, ovoid to elliptical, orange to brown ...... 8. Pleuridium, p. 463 Ceratodon · DITRICHACEAE 445 1. CERATODON Bridel, Bryol. Univ. 1: 480. 1826 · [Greek keratos, horn, and odon, tooth, alluding to peristome teeth forked like goat horns]

Terry T. McIntosh

Plants in loose to dense tufts, turfs, or mats, green to dark green, brownish green, light green, or yellow-green, often tinged reddish brown or purple. Stems (0.2–)1–3(–4) cm, often branched; rhizoids at base, papillose. Leaves erect-patent, contorted or somewhat crisped, rarely straight when dry, lanceolate, ovate-lanceolate, or triangular-lanceolate, or elliptical to ovate and somewhat concave, margins recurved to near apex, rarely plane, irregularly serrate or smooth distally; costa sub-percurrent to excurrent, sometimes as a long, smooth awn, 1 row of guide cells, two stereid bands, hydroid cells present between guide cells and abaxial stereids; medial laminal cells of somewhat uneven shape and size across leaf, more or less quadrate or short- rectangular, often irregularly angled or rarely rounded, non-pitted. Specialized asexual reproduction absent or as multicellular filamentous propagules with thin walls scattered along the stems or occasionally as rhizome nodules. Sexual condition dioicous; male and female plants about the same size; perigonial leaves ovate, concave, short-acuminate or rarely long-acuminate in well-developed plants; perichaetial leaves convolute-sheathing, abruptly subulate to gradually acuminate. Seta red, purplish, yellow, or yellow-orange, elongate, twisted when dry, erect. Capsule erect to inclined or horizontal, exserted, dark red to reddish or purplish brown, to pale brown, pale yellow or yellow-orange, oblong-ovoid to oblong-cylindric or cylindric, often somewhat asymmetric and deeply furrowed, smooth to strongly sulcate when dry, usually strumose; annulus of 2–3 rows of large, deciduous, revoluble cells; operculum conic to long- conic, straight; peristome single, teeth 16, split nearly to their base into 2 filiform segments free to united at their nodes basally, 5–18 articulations, basal membrane present, finely papillose to spinulose-papillose. Calyptra cucullate. Spores globose, smooth to finely papillose. Species 3 (2 in the flora): worldwide. Historically, Ceratodon has been a troubling genus. Taxonomic interpretations, especially with respect to C. purpureus in the broad sense, have varied widely, mainly because of the high degree of environmental and suspected genetic variation across its range. J. S. Burley and N. M. Pritchard (1990) provided the most thorough treatment of Ceratodon to date, reducing the number of species to four and subspecies of C. purpureus to three. One of their species, C. conicus, is treated here as a subspecies of C. purpureus, based on the apparent gradation and reduction of all of the characters that they used in their treatment. However, there remains a great need for a detailed study of this genus within North America.

SELECTED REFERENCES Burley, J. S. and N. M. Pritchard. 1990. Revision of the genus Ceratodon (Bryophyta). Harvard Pap. Bot. 2: 17–76. Snider, J. A. 1994. Ceratodon. In: A. J. Sharp, et al., eds. The flora of Mexico. Mem. New York Bot. Gard. 69: 103.

1. Vegetative leaves elliptic to ovate-lanceolate, concave, obtuse; distal laminal cells usually 12–16 mm, sometimes longer; leaf margins plane to weakly recurved and usually entire; most costa sub-percurrent; capsule ovate to ovate-cylindrical, about 1 mm; spores usually19–21 µm; restricted to Arctic regions ...... 1. Ceratodon heterophyllus 1. Vegetative leaves usually lanceolate to ovate-lanceolate, acute to short-acuminate; distal laminal cells usually 8–12 mm; leaf margins recurved and usually toothed distally; costa percurrent to long-excurrent; capsule ovate-cylindrical to cylindrical, usually longer, to 3 mm; spores usually 11–14 µm; widespread ...... 2. 446 DITRICHACEAE · Ceratodon

CERATODON ° DISTICHIUM

1. Ceratodon heterophyllus Kindberg, Ottawa Ceratodon heterophyllus has also been treated as Naturalist 5: 179. 1892 C. purpureus forma heterophyllus (Kindberg) Britton, Ceratodon purpureus var. and R. R. Ireland (1980) considered it to be a variety of C. purpureus, but J. S. Burley and N. M. Pritchard (1990) 5 obtusifolius Limpricht; C. purpureus 5 var. rotundifolius Berggren provided ample evidence that it is a distinct species. The 5 5 broadly ovate leaves of C. heterophyllus grade into some Plants in dense tufts or mats, green alpine variations of C. purpureus. to dark green to brownish green. Stems 0.3–1 cm. Leaves loosely SELECTED REFERENCE Ireland, R. R. 1980. The taxonomic status of Ceratodon heterophyllus. Bryologist 83: 234–237. imbricate, somewhat contorted when dry, ovate to ovate- 2. Ceratodon purpureus (Hedwig) Bridel, Bryol. Univ. lanceolate, concave and often 1:480. 1826 somewhat cucullate, (0.35–)0.5–0.9(–1.5) mm, margins plane to weakly recurved, often only at mid-leaf, and Dicranum purpureum Hedwig, Sp. entire to, rarely, weakly toothed distally, apices obtuse; 5 Musc. Frond., 136, plate 36. 1801; 5 Ceratodon purpurascens (Hedwig) most costae ending before apex; medial laminal cells 5 5 (9–)12–16(–22) µm, thin-walled to somewhat thickened. 5 Jennings; C. purpureus var. 5 5 5 5 5 5 5 purpurascens (Hedwig) Bridel; C. 5 Seta (0.9–)1.5(–2.5) cm, red. Capsule ovate-cylindric to, 5 5 5 5 5 5 5 5 5 55 5 5 5 5 5 5 55 purpureus var. xanthopus Sullivant 5 5 5 occasionally, ovate, (0.9–)1–1.2(–1.5) mm, strongly 5 5 5 5 5 555 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 sulcate when dry; peristome segments free at their nodes, 5 5 5 5 Plants in open to dense tufts, turfs, 5 5 finely papillose, dark red with pale borders to, rarely, or mats, green, dark green, completely pale. Spores (18–)19–21(–22) µm. brownish green, light green or Capsules mature early summer–late fall. Sandy, yellow-green, usually darker proximally, often tinged usually moist soil, Arctic habitats; low elevations reddish brown or purple. Stems (0.2–)1–3(–4) cm. (0–200 m); Greenland; N.W.T., Yukon; Alaska; Eurasia. Leaves crowded, erect-patent to contorted or somewhat In Northwest Territories, Ceratodon heterophyllus is crisped, rarely straight when dry, lanceolate, ovate- found only on Prince Patrick Island. Ceratodon · DITRICHACEAE 447 lanceolate, or triangular-lanceolate, 0.35–2.8 mm, brown. Capsule usually inclined to horizontal, (0.8–)1.3– margins recurved to near apex or rarely plane, irregularly 1.8(–3) mm, usually arcuate, red to red-brown to purplish serrate to uneven or smooth distally, apices acute to short- to, occasionally, light brown, deeply sulcate when dry, acuminate or, rarely, obtuse; costa strong, sub-percurrent usually strumose, occasionally light brown. Peristome to excurrent, sometimes as a long, smooth awn, medial teeth usually bordered, usually with 8–16 articulations. laminal cells (6.5–)8–12(–14) µm, cell walls even, usually Capsules mature early summer–late fall. Various of medium thickness, often somewhat thicker and habitats, but most common on open soil, also rock ledges, rounded at the cell angles. Seta 1–3(–4) cm, various tree bases, roof tops, old wood, a common colonizer of shades of red, orange, or yellow. Capsule oblong to long- soil following fires; low to high elevations; Greenland; cylindric, (1–)2–2.5(–3) mm, smooth to strongly sulcate Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., when dry; free to united at their nodes, finely papillose Nunavut, Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, to spinulose-papillose, dark red and bordered to Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., completely pale and absent borders. Spores (10–)11– Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., 14(–17) µm. Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., Subspecies 4 (3 in the flora): nearly worldwide. N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., 1. Plants usually of various shades of green to red- brown; seta red to dark brown; capsule inclined W.Va., Wis., Wyo.; Mexico; Eurasia; Pacific Islands to horizontal, oblong to cylindric, strumose, deeply (Hawaii). sulcate when dry, usually red to red-brown to purplish, occasionally light brown ...... 2b. Ceratodon purpureus subsp. conicus (Hampe) ...... 2a. Ceratodon purpureus Dixon, Stud. Handb. Brit. , 68. 1896 subsp. purpureus Trichostomum conicum Hampe in 1. Plants pale green to yellow-green to yellowish Müller Hal., Syn. Musc. Frond. 1: brown; seta pale yellow to yellow-orange, rarely reddish; capsule slightly inclined to erect, narrowly 575. 1849; Ceratodon conicus cylindric to cylindric, not or weakly strumose, (Hampe) Lindberg 5 smooth to sulcate when dry, usually pale brown to 5 Plants in compact mats, usually 5 5 yellow (golden) -orange. 5 yellow-green. Stems (0.2–)0.3– 2. Stems usually less than 0.5 cm; distal leaves 0.6(–3) cm. Leaves straight to relatively compact, straight to slightly twisted slightly twisted when dry, usually when dry, usually forming a comal tuft, slightly forming a comal tuft, slightly spreading when wet, 0.6–1.2 mm, margins often entire; costa long-excurrent as a smooth spreading when wet, 0.6–1.2 mm, margins often entire; awn on many leaves, awns sometimes as long costae long-excurrent as a smooth awn on many leaves, as leaf blade ...... 2b. Ceratodon purpureus awns sometimes as long as leaf blade. Seta yellow to subsp. conicus yellow-orange. Capsule usually slightly inclined to erect, 2. Stems usually greater than 1 cm; distal leaves usually straight, (0.8–)1–1.8(–2.2) mm, pale brown to more open, usually crisped when dry, not yellow (golden) orange, smooth to sulcate when dry, forming a comal tuft, spreading when wet, 1.2– usually weakly strumose. Peristome teeth faintly bordered 1.8 mm, margins often toothed; costa to unbordered, usually with 5–9 articulations. percurrent to slightly excurrent ...... Capsules mature early summer–late fall. Common on ...... 2c. Ceratodon purpureus calcium-rich soils of arid habitats; moderate elevations subsp. stenocarpus (300–800 m); B.C.; Idaho, Minn., Oreg., Wash.; Eurasia; n Africa; Atlantic Islands (Canary Islands). 2a. Ceratodon purpureus (Hedwig) Bridel subsp. Subspecies conicus is apparently widespread in some purpureus arid regions of western North America. J. S. Burley and Dicranum purpurascens Hedwig N. M. Pritchard (1990) considered its status in North 5 Plants in open to dense tufts, turfs, America to be uncertain. However, fertile collections, 5 although uncommon, fit well within their concept. It 5 or mats, green, dark green, to 5 5 brownish green, rarely yellow- appears to be widespread in the semi-arid steppe regions 5 5 5 5 5 5 5 5 of central Washington and adjacent British Columbia. 5 5 5 green. Stems (0.3–)0.6–1.4(–4) cm. 5 5 5 5 5 5 55 5 5 5 5 5 5 5 55 5 5 5 In these arid habitats, it is often admixed with other low- 5 5 5 5 555 Leaves erect-patent to contorted or 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 growing species (e.g., Bryum spp. and Didymodon spp.) 5 5 somewhat crisped when dry, rarely 5 forming a comal tuft, patent to as part of the biological crust community. erect-patent to spreading when wet, 0.35–2.8 mm, distal margins usually toothed; costa percurrent to slightly excurrent. Seta usually red to dark 448 DITRICHACEAE · Ceratodon· Distichium

2c. Ceratodon purpureus subsp. stenocarpus (Bruch slightly inclined to erect, usually arcuate, (1–)1.7–2.3 & Schimper) Dixon, Bull. New Zealand Inst. 3: 50. (–3.7) mm, pale brown to yellow (golden) orange, smooth 1914 to sulcate when dry, weakly strumose to struma absent. Ceratodon stenocarpus Bruch & Peristome teeth usually bordered, usually with 8–16 Schimper, Bryol. Europ. 2: 146. articulations. 1846 Capsules mature early summer–late fall. Soil, tree bases, rock ledges, often on burned ground; low to high Plants usually in open turfs and elevations; Ariz., Calif., N.Mex., Tex.; Mexico; West mats, usually yellow-green. Stems Indies; Central America; n South America; Eurasia;

5 (0.3–)0.6–1.4(–4) cm. Leaves Africa. 5 5 5 erect-patent to contorted or J. S. Burley and N. M. Pritchard (1990) noted that somewhat crisped when dry, rarely subsp. stenocarpus is mainly tropical to sub-tropical, and forming a comal tuft, patent to frequently at higher elevations within these regions, but erect-patent to spreading when wet, 0.35–2.8 mm, distal also note its distribution in southwestern North America. margins usually toothed; costae percurrent to slightly excurrent. Seta pale yellow to yellow-orange. Capsule

2. DISTICHIUM Bruch & Schimper, Bryol. Europ. 2: 153. 1846 · [Greek distichos, in two rows, alluding to leaves]

Rodney D. Seppelt

Plants slender, elongate, in dense tomentose tufts, yellowish green to dark green. Stems 1–6 cm, simple or branched; rhizoids from base to middle of stem forming a conspicuous tomentum. Leaves distichous, linear subula spreading from erect, whitish ovate-lanceolate or oblong sheathing base, margins plane to slightly incurved, becoming denticulate in subula particularly 1 1 near the apex; costa excurrent, occupying most of subula, /4– /3 width of leaf at base, subula roughened abaxially; lamina cells of sheathing base linear to oblong-linear, linear-flexuose or rectangular, becoming rectangular distally and quadrate to short-rectangular in subula. Specialized asexual reproduction unknown. Sexual condition autoicous, paroicous or synoicous; perigonia axillary, or on short branches proximal to perichaetium; perichaetial leaves not differentiated. Seta yellow-brown to reddish, elongate, erect. Capsule erect and symmetric or inclined and asymmetric, exserted, brown, cylindric to ovoid-cylindric, ± wrinkled when dry and empty; annulus of 2–3 rows of large, pale cells, deciduous; operculum conic, straight; peristome single, teeth16, variously split to near the base into 2(–3) minutely papillose filaments, teeth sometimes arranged in 8 groups of 2 teeth. Calyptra cucullate. Spores globose to ovoid, finely papillose. Species 14 (3 in the flora): worldwide. var. curvatum Flowers was described as a probable hybrid between D. capillaceum and D. inclinatum, characterized by capsule cylindric and strongly curved, and spores 20–23 µm.

1. Capsule erect, cylindric, straight to slightly arcuate, spores 15–25 µm ...... 1. Distichium capillaceum 1. Capsule inclined, ovoid to oblong-ovoid, spores more than 25 µm. 2. Peristome with a yellowish to hyaline basal membrane uniting teeth into 8 separated groups each of 2 teeth ...... 2. Distichium hagenii 2. Peristome of 16, evenly spaced, irregularly divided or perforate teeth ...... 3. Distichium inclinatum Distichium · DITRICHACEAE 449

1. Distichium capillaceum (Hedwig) Bruch & Schimper, Capsules mature late summer–fall. Usually calcareous Bryol. Europ. 2: 156. 1846 soil, often in frost cushions; low to high elevations; Cynontodium capillaceum Hedwig, Greenland; N.W.T., Nunavut; Alaska; n and Arctic Europe; e Asia (China, Mongolia); Arctic Asia (Siberia). 5 Sp. Musc. Frond., 57. 1801

5 Distichium hagenii is a primarily high Arctic or high

5 Stems to ca. 6 cm, occasionally 5 5 elevation species, morphologically close to D. inclinatum longer. Sexual condition paro- 5 5 5 and sometimes considered as synonymous with that 5 5 5 5 5 5 5 5 icous. Seta to 2 cm, straight to 5 5 5 5 species. The primary difference is in the peristome. The 55 5 5 5 5 5 5 5 5 5 5 somewhat flexuose, smooth, red 5 5 16 peristome teeth of D. hagenii are grouped in eight 5 5 or reddish brown, occasionally pairs united by a pale yellowish basal membrane, each yellowish brown. Capsule brown, tooth irregularly split and perforate. A report of the 1–2 mm, erect, cylindric to ovoid- species from Newfoundland is referable to D. inclinatum cylindric, straight to weakly arcuate, becoming ± wrinkled (redetermined by G. R. Brassard according to H. A. Crum when dry; operculum to 0.5 mm; peristome teeth evenly and L. E. Anderson 1981). In the southern part of the spaced, lanceolate, divided nearly to the base into 2(–3) European range, it grows on sandy or loam soil close to filaments, smooth to papillose or sometimes ± striolate. the sea. Spores densely and finely papillose, 15-25 µm. Capsules mature summer–fall. Soil, rock, crevices, 3. Distichium inclinatum (Hedwig) Bruch & Schimper, ledges, banks, occasionally bark; Greenland; Alta, B.C., Bryol. Europ. 2: 157. 1846 Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Alaska, Ariz., Calif., Colo., Cynontodium inclinatum Hedwig, Idaho, Ind., Iowa, Maine, Mich., Mont., Nev., N.H., 5 Sp. Musc. Frond., 58. 1801 5

N.Mex., N.Y., N.Dak., Oreg., S.Dak., Utah, Vt., Wash., 5 Stems to ca. 3 cm, mostly shorter. 5 5 Wis., Wyo.; Mexico; Central America; South America; Sexual condition autoicous. Seta 5 5 5 5 5 5 5 Eurasia; n, c, e, se Asia; Africa; Pacific Islands; Australia; 5 to 2 cm, straight to somewhat 5 5 5 5 5 5 5 5 Arctic; Antarctic. 5 flexuose, smooth, red or reddish 5 5 Plants of Distichium capillaceum form dense, rather brown, occasionally yellowish silky tufts and the slender, spreading, distichous leaves brown. Capsule brown, 1–1.5 with shiny, whitish, oblong, sheathing bases are mm, inclined, ovoid, becoming characteristic. This is a taller species than D. inclinatum, ± wrinkled when dry; operculum to 0.3 mm; peristome with plants less crowded, capsules erect-symmetrical and evenly spaced, lanceolate, divided nearly to the base into cylindric, and spores smaller. In more northerly or alpine 2(–3) filaments, smooth to papillose or sometimes regions with more severe climatic conditions, the plants ± striolate. Spores densely and finely papillose, are often shorter, more compact, and have shorter leaves. occasionally roughened, 30–45(–48) µm. Capsules mature summer–fall. Calciphilic, sandy soils, 2. Distichium hagenii H. Philibert, Rev. Bryol. 23: 36, rocks, ledges; low to high elevations; Greenland; Alta., plate 1, figs. 2, 3. 1896 B.C., Man., N.B., Nfld. and Labr., N.W.T., Nunavut, Distichium inclinatum subsp. Ont., Que., Yukon; Alaska, Calif., Colo., Mich., Minn., Mont., Nev., N.Y., N.Dak., Utah, Wis., Wyo.; Mexico; 5 hagenii (H. Philibert) J. J. Amann; Europe; Eurasia; e, c, n Asia; Arctic. 5 D. inclinatum var. hagenii

5 5 (H. Philibert) Mönkemeyer Distichium inclinatum is similar to D. capillaceum and D. hagenii, differing from the former in the inclined, ovoid Stems to ca. 2 cm, occasionally capsule, shorter stems, more closely set leaves, and larger longer. Sexual condition paro- spores. It differs from the latter primarily by features of icous or synoicous. Seta to 2 cm, the peristome: the peristome teeth of D. hagenii have a straight to somewhat flexuose, basal membrane and the teeth are arranged in eight smooth, red or reddish brown, irregular but separated groups of two teeth each, rather occasionally yellowish brown. Capsule brown, 1–1.5 than being evenly spaced as in D. inclinatum and mm, inclined, ovoid to oblong-ovoid, becoming D. capillaceum. ± wrinkled when dry; operculum to 0.3 mm; peristome teeth 16, united below by a pale yellow or hyaline membrane, the teeth in 8 groups of 2, irregularly split and perforated, smooth or very finely papillose. Spores finely papillose to roughened, 30–45 µm. 450 DITRICHACEAE · Ditrichum 3. DITRICHUM Hampe, Flora 50: 181. 1867, name conserved · [Greek di-, two, and trichos, hair, alluding to peristome split longitudinally into two segments]

Rodney D. Seppelt Robert R. Ireland Jr.

Harold Robinson

Plants in loose to dense tufts, green to yellowish green distally, yellow-brown to brown proximally. Stems short or reaching 2 cm or more, simple or sometimes with a few branches; rhizoids at base, smoth. Leaves rigid to flexuose or sometimes somewhat falcate when dry, erect-spreading when wet, lanceolate to subulate from a more or less sheathing base; margins entire throughout or denticulate near the apex; costa percurrent or excurrent, occupying most 1 1 of subula, /6– /3 width of leaf base, 1 row of guide cells, 2 stereid bands, adaxial stereid band sometimes weak, rarely absent; medial lamina cells quadrate to short-rectangular, becoming longer and thinner-walled proximally toward margins, smooth or rarely papillose at both ends. Specialized asexual reproduction occasionally by rhizoidal tubers. Sexual condition monoicous or dioicous; perichaetial leaves usually with a longer and more or less sheathing base and shorter subulate than stem leaves. Seta pale yellow to dark reddish brown, elongate, erect or flexuose. Capsule mostly erect and symmetric, sometimes ± inclined and arcuate, exserted, ovoid to cylindric, smooth; annulus present, deciduous; operculum conic to short-rostrate; peristome single, teeth16, split into 2 filiform segments or sometimes irregularly perforate or split, with or without a short basal membrane, papillose to spiculose. Calyptra cucullate. Spores globose, very finely papillose, verrucose, or with somewhat vermicular ornamentation. Species ca. 90 (11 in the flora): worldwide, including maritime Antarctic region. Ditrichum occurs from near sea level up to montane regions, on a wide range of soils, but is found occasionally on rock; some species are calciphilic.

1. Plants densely tufted, stems ± tomentose proximally. 2. Stems 1–4 cm; leaves to 3 mm, from an ovate-sheathing base sharply contracted to the subula; costa abaxially strongly convex; lamina cells near costa with weakly nodulose longitudinal walls; plants commonly fruiting ...... 2. Ditrichum flexicaule 2. Stems to 7 cm or more; leaves from an elongate-ovate base tapering gradually to the long slender subula; costa abaxially weakly convex; basal laminal cells with weakly to strongly nodulose longitudinal walls; rarely found fruiting ...... 3. Ditrichum gracile 1. Plants loosely to densely tufted or gregarious; stems, if tomentose, only so at extreme base. 3. In cross section, distal leaf lamina partially 1-stratose with 2-stratose margins. 4. Leaves erect-appressed to erect-patent when moist. 5. Leaves oblong-lanceolate, widest proximally to middle, tapering to a blunt apex; lamina cells thin-walled, rectangular throughout, slightly shorter and narrower towards apex; seta to 2.5 cm, yellowish to orange-brown, erect; peristome teeth 200–220 µm, perforate, divided into 2 adhering filaments, finely papillose ...... 5. Ditrichum lineare 5. Leaves lanceolate to linear-lanceolate, gradually acuminate; lamina cells ± incrassate, subquadrate to short-rectangular distally, elongate-rectangular proximally; seta to 1.5 cm, reddish with age; peristome teeth 200–250 µm, the filaments finely and obliquely ridged and lightly papillose ...... 8. Ditrichum pusillum Ditrichum · DITRICHACEAE 451

4. Leaves erect-spreading when moist. 6. Stems fastigiately branched from base, dichotomous distally; leaves linear- lanceolate, margins subserrulate distally, apex coarsely toothed; seta to 2.5 cm, pale yellow; capsule straight and erect or slightly curved, orange- to dark red- brown at maturity, elliptical, narrowed at mouth, 2–3 mm, flattened when dry; peristome teeth 600–800 µm, spiculose-papillose; autoicous ...... 6. Ditrichum montanum 6. Stem branching distally from base; leaves lanceolate to linear-lanceolate, margins entire to serrulate distally, apex weakly toothed; seta shorter, 0.8–2 cm, red to orange-brown; capsule symmetric to slightly curved, 1–3 mm, not flattened when dry; peristome teeth 200–500 µm, papillose to spiculose; dioicous. 7. Stems to 2 cm, often branched; leaves 1.5–4.5 mm, apex entire or serrulate, margins broadly recurved from base to leaf middle; leaf cross section 2- stratose on margins and sometimes near costa; seta 1.5–2 cm, red; capsule usually symmetric, straight and erect, rarely curved, 1.5–3 mm long, dark brown to reddish; peristome teeth 200–500 µm, twisted when dry ...... 1. Ditrichum ambiguum 7. Stems to 0.5 cm, seldom branched; leaves 1–3 mm, apex serrulate, margins plane or narrowly recurved from above leaf base to leaf middle; leaf cross section 2-stratose only at or near margins; seta 0.8–1.2 cm, orange-yellow, brownish or reddish; capsule usually asymmetric, erect, curved, 1–2 mm, yellow or light brown; peristome teeth 200 µm, nearly straight . . 11. Ditrichum tortuloides [3. Shifted to left margin.—Ed.] 3. In cross section, distal leaf lamina 2-stratose from costa to margins. 8. Stem leaves 1.5–3 mm, from an ovate to oblong base gradually tapered to a channelled subula, erect-patent to subsecund; dioicous ...... 4. Ditrichum heteromallum 8. Stem leaves longer, 3–7 mm, long-subulate from an ovate to short-rectangular base, spreading, flexuose to subsecund; autoicous. 9. Leaves to 5 mm; seta to 2.5 cm, orange-yellow, becoming reddened at maturity; capsule ovoid-cylindric, ± asymmetric and slightly curved, pale brown, suberect, flattened when dry; peristome teeth to 1500 µm, densely spiculose-papillose; spores yellow-brown, 11–19 µm, vermicular papillose-verrucose ...... 9. Ditrichum rhynchostegium 9. Leaves 3–7 mm; seta 1–3 cm, yellow or becoming reddish brown at the base when mature; capsules subcylindric to cylindric, not flattened when dry; peristome teeth to 800 µm, finely papillose to spiculose-papillose; spores brown, 15–30 µm, coarsely roughened-papillose. 10. Leaves long-subulate from a short-ovoid sheathing base; seta to 2.5 cm, yellow, becoming reddened at the base with maturity; capsule suberect, subcylindric, 1–2.5 mm; peristome teeth pale brown to orange-brown, 300–800 µm, spiculose- papillose; spores 15–30 µm ...... 7. Ditrichum pallidum 10. Leaves narrow filiform-subulate from an ovate-lanceolate sheathing base; seta 1–3 cm, yellow; capsule cylindric, 1.5–3 mm; peristome teeth pale yellow-brown, to 300 µm, irregularly perforate, finely papillose; spores 20–30 µm . . . 10. Ditrichum schimperi

1. Ditrichum ambiguum Best, Bull. Torrey Bot. Club 20: recurved from the base to near mid lamina, weakly to 117. 1893 strongly serrulate from mid lamina to apex, entire or Plants in loose to dense tufts, green serrulate at the somewhat blunt apex, 2-stratose distally to yellowish green, becoming and sometimes extending inward for several cells; costa 1 1 5 yellowish brown with age, dull. distinct, percurrent, occupying /6– /3 the width of the Stems 0.7–2 cm, with a few leaf base; lamina cells thick-walled, distal cells quadrate, 5 reddish rhizoids at the base. irregularly sub-quadrate to short-rectangular, 8–24 × 4– 5 5 Leaves erect-spreading, somewhat 8 µm, becoming broader and longer near the base. 5 crisped when dry, 1.5–4.5 mm, Specialized asexual reproduction unknown. Sexual lanceolate to linear-lanceolate, condition dioicous. Seta red, 1–2 cm, erect. Capsule channelled, lamina with a few erect, usually straight and symmetric or sometimes slightly scattered 2-stratose cells midway between margins and curved, dark brown or reddish, cylindric, 1.5–3(–3.2) costa in median to distal part of leaf; margins broadly mm, occasionally slightly enlarged at base; operculum 452 DITRICHACEAE · Ditrichum

DITRICHUM

rostrate, 0.4–0.8 mm; peristome red, 200–500(–800) µm, with a swollen base in D. tortuloides. The geographic twisted when dry, teeth divided to near base into two ranges of the two taxa are quite disparate. The species equal filaments, strongly papillose to spiculose. Spores has been reported outside North America by B. H. Allen round, 6–13 µm, appearing smooth to minutely papillose. (1994), from Guatemala and Panama. Capsules mature spring and summer (Apr–Jul). Moist, sandy or sometimes clay banks, soil on upturned stumps, 2. Ditrichum flexicaule (Schwägrichen) Hampe, Flora crevices of sandstone cliffs, often in clearings along roads; 50: 182. 1867 low to moderate elevations (100–500 m); B.C. (including Cynodontium flexicaule Queen Charlotte Island); Alaska, Calif., Oreg., Wash.; 5 Schwägrichen, Sp. Musc. Frond.

Central America (Guatemala, Panama). 5 Suppl. 1(1): 113, plate 29. 1811 5 5 Ditrichum ambiguum, a western species, is very close 5 Plants usually in dense tufts, green 5 5 to an eastern species, D. tortuloides, but differs in the 5 5 5 5 5 5 5 5 5 to brownish green, dull. Stems following morphological characters: stems often 5 5 5 5 5 1–4 cm, usually tomentose prox- branched and taller, 7–20 mm compared to the shorter, 5 2–5 mm, usually simple stems of D. tortuloides; leaf imally, sometimes only slightly so, margins broadly recurved, entire or serrulate at a ± matted together. Leaves stiff to somewhat blunt apex, compared to the narrowly flexuose, rarely ± falcate, to ca. 3 recurved, serrate to strongly serrate margins from mid- mm, from an ovate to elongate-ovate, sheathing base leaf to an acute apex in D. tortuloides; leaf laminae with contracted rather suddenly to the subula, lamina 1- 2-stratose margins and occasional 2-stratose regions stratose; margins entire or very weakly denticulate at the between the margins and the costa in the middle to distal apex, often 2-stratose distally on the margins; costa 1 1 half of the leaf, compared to the 2-stratose regions only occupying /4– /3 width of the leaf base, ± convex on the margins in D. tortuloides; capsules dark brown to abaxially, in section with weakly defined adaxial and reddish, 1.5–3.2 × 0.2–0.5 mm, straight and symmetric abaxial stereid bands; cells of the subula short-rectangular to rarely slightly arcuate with an occasionally slightly to elongate-rhomboid, becoming more elongate in the swollen base, compared to the yellow or light brown, 1– base, cells adjacent to the costa with only weakly nodulose 2.5 × 0.2–0.3 mm, curved and asymmetric capsules often longitudinal walls, narrower towards the margins. Ditrichum · DITRICHACEAE 453

Specialized asexual reproduction unknown. Sexual from an elongate ovate sheathing base to a long subula, condition dioicous; male plants shorter than female lamina 1-stratose proximally, often 2-stratose distally in plants. Seta dark red-brown, to 2 cm, ± flexuose. Capsule the subula; margins spinulose-denticulate in distal part ± erect, dark brown, cylindric, to 1.5 mm; operculum of the subula or sometimes ± entire, often 2-stratose high- conic to conic-rostrate, 0.7–0.9 mm; peristome teeth distally; costa occupying 1/4–1/3 width of leaf base, weakly 2-fid nearly to the short basal membrane, densely abaxially convex, with poorly developed stereid bands spiculose-papillose, light brown proximally, pale distally, abaxially and adaxially; cells of the subula and distal 300–450 µm. Spores 9–12 µm, finely papillose. part of leaf base short, isodiametric to rhomboid to short Capsules seldom produced, mature summer (Jun–Jul). rectangular, those of the leaf base becoming elongate, Calciphilic, rock or soil over rock, especially bluffs, cliff rectangular, with ± nodulose longitudinal walls, shelves or crevices of cliffs, usually in dry and exposed particularly near the costa, cells of the basal margins places; low to high elevations; Greenland; Alta., B.C., narrower. Specialized asexual reproduction unknown. Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Sexual condition dioicous; sporophytes rare; male plants Ont., Que, Sask., Yukon; Alaska, Colo., Idaho, Mich., slightly smaller than rarer female plants. Seta dark Minn., Mont., Wash., Wyo.; Central America reddish brown, to 2.5 cm, ± flexuose. Capsule erect and (Guatemala); Europe; Asia; Pacific Islands (New Guinea, symmetric to slightly inclined, dark brown, ± cylindric, New Zealand). 1.5–2 mm; operculum high-conic to conic-rostrate, to Ditrichum flexicaule in the broad sense (including D. about 1 mm; peristome teeth about 400 µm, pale, 2-fid, gracile) is exceedingly variable in morphology, not only divided to near base, densely papillose, fragile. Spores in North America (A. J. Grout 1928–1940, vol. 1, part 12–15 µm, finely papillose. 1; H. A. Crum and L. E. Anderson 1981) but throughout Capsules rarely produced, mature summer (Jul). Soil, the world (R. D. Seppelt 1982; A. A. Frisvoll 1985). rocks; moderate to high elevations (to 4000 m); While many workers have treated the variation and the Greenland; B.C., Nfld. and Labr., N.W.T., Nunavut, Ont., described variant taxa as one highly polymorphic species Que.; Alaska, Colo., Minn., Mont., Wyo.; Mexico; (Crum and Anderson; M. F. V. Corley et al. 1981), others Central America (Guatemala, El Salvador); South (Frisvoll; E. Nyholm 1986+, fasc. 1; I. Novotny 1996) America (Colombia); Europe; Asia (Japan, Taiwan); have recognized two principal entities, D. flexicaule and Pacific Islands (New Guinea, New Zealand). D. crispatissimum (= D. crinale (Taylor) Kuntze). We B. H. Allen (1994) included Ditrichum crispatissimum have followed this latter interpretation. A comprehensive and D. giganteum as synonyms of D. gracile, an molecular analysis of the group would be highly desirable. interpretation we have followed here. As with D. Crum and Anderson related all variation in habit and flexicaule, a detailed molecular analysis of this and related microscopic details to environmental conditions, taxa may help considerably in ascertaining taxonomic particularly shade and moisture. Frisvoll differentiated affinities. two taxa largely on the basis of gametophytic features. Notwithstanding the considerable variability exhibited 4. Ditrichum heteromallum (Hedwig) E. Britton in N. L. by these taxa, we also consider them distinct. While often Britton et al., N. Amer. Fl. 15: 64. 1913 found infertile, D. flexicaule is more commonly found Weissia heteromalla Hedwig, Sp. with sporophytes than is D. gracile. Both are calciphiles. Musc. Frond., 71. 1801; 5 Didymodon homomallus Hedwig; 3. Ditrichum gracile (Mitten) Kuntze, Revis. Gen. Pl. 2: Ditrichum homomallum (Hedwig) 835. 1891 5 Hampe; D. zonatum (Bridel) 5 Leptotrichum gracile Mitten, 5 Kindberg; D. zonatum var.

5 Hooker’s J. Bot. Kew Gard. Misc. 3: scabrifolium Dixon 5 353. 1851; L. crispatissimum

5 Plants in loose to dense tufts, 5 Müller Hal.; Ditrichum yellowish green. Stems to 1 cm, 5 5

5 5 crispatissimum (Müller Hal.) Paris; 5 simple, seldom branched. Leaves 1.5–3 mm, erect- 5 5 5 D. giganteum R. S. Williams spreading, sometimes slightly secund, from an ovate to 5 Plants in tufts, yellowish brown to oblong base tapering gradually to a long channelled dark green, often shiny. Stems subula, lamina 2-stratose distally; margins plane, 1- very variable in length, to 7 cm or stratose proximally, 2-stratose in the middle to distal more, simple or with relatively few branches; loosely parts; costa broad, occupying most of the subula, in compacted and then sparsely tomentose, or closely section with a distinct abaxial and poorly developed compact and rather densely tomentose. Leaves often adaxial stereid band; cells of subula and distal lamina ± falcate, slightly or not flexuose, subula of leaves often elongate-rectangular, longer in the leaf base, smooth or spirally twisted together, 4–7 mm, tapering ± gradually sometimes papillose at both ends, especially near leaf 454 DITRICHACEAE · Ditrichum apices. Specialized asexual reproduction by rarely mm; peristome divided by perforations into 2 ± adhering produced rhizoidal tubers. Sexual condition dioicous. divisions, 200–220 µm, finely papillose. Spores 13–16 Seta reddish brown, 1–2.5 mm. Capsule erect, reddish µm, appearing smooth or very finely verrucose, brown. brown, oblong to cylindric, symmetric, 0.5–1.5 mm; Capsules mature spring (Apr–May). A pioneer species, peristome teeth pale orange, about 300 µm, lightly bare clay, sandy or gravely soil banks, wooded clearings, papillose; operculum conic-rostrate, blunt, 0.4–0.5 mm. trails, roads and other often disturbed habitats; low Spores 10–15 µm, finely papillose. elevations; N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que.; Capsules mature summer (Jun–Aug). Soil; low to high Ala., Ark., Del., D.C., Conn., Fla., Ga., Ill., Ind., Iowa, elevations (50–1500 m or higher); B.C.; Alaska, Oreg., Ky., Maine, Md., Mass., Mich., Mo., N.H., N.J., N.Y., Wash.; South America (Colombia); Europe; Asia (China, N.C., Ohio, Pa., R.I., Tenn., Vt., Va., Wis.; Europe; Japan, Taiwan); Atlantic Islands (Iceland). e Asia (Japan). Rhizoidal tubers were first reported for Ditrichum Rhizoidal tubers, consisting of swollen rhizoidal cells heteromallum by S. Risse (1985) from European material and arising laterally from axial rhizoids, are known for and have also been noted in Japanese material by H. Ditrichum lineare only from Asia (T. Matsui et al. 1985; Deguchi and T. Matsui (1986). They have the appearance Matsui and Z. Iwatsuki 1990). This species is very similar of short filaments with swollen, contorted rhizoid cells. in appearance to D. pusillum but is distinguished by the Ditrichum zonatum (Bridel) Kindberg, including the var. rectangular cells of the sheathing leaf base. The leaf scabrifolium Dixon, appears to be only a small form of margins of North American specimens of D. lineare are D. heteromallum with shorter, appressed leaves that are entire and plane or rarely only weakly recurved, often more 2-stratose, especially near the base, and leaf irregularly 2-stratose but not noticeably thickened, and cells that are sometimes papillose at the ends. We have the lamina cells are elongate rectangular to linear. The not seen specimens that support the Wisconsin report by leaf margins in D. pusillum are irregularly thickened, F. Bowers and S. Freckman (1979) and believe the record serrulate, more strongly recurved, and the lamina cells to be dubious. generally subquadrate to short-rectangular. Ditrichum lineare also has a subula shorter than the sheathing base, 5. Ditrichum lineare (Swartz) Lindberg, Acta Soc. Sci. which is unusual in the genus. This macroscopic feature Fenn. 10: 108. 1871 is sometimes used to distinguish it from the closely related Didymodon linearis Swartz, Adnot. D. pusillum, which has a subula longer than the sheathing Bot., 100. 1829; Ditrichum base, typical of many species in the genus (R. R. Ireland vaginans (Sullivant) Hampe; 1982). Trichostomum vaginans Sullivant 5 6. Ditrichum montanum Leiberg, Bull. Torrey Bot. Club 5 5 5 5 5 5 Plants in loose to dense tufts, 5 5 20: 112, plate 143. 1893 5 5 5 5 5 55 5 5 5 5 5 5 5 55 yellowish green. Stems to 1(–1.5) 5 5 5 5 5 5 Plants usually in tufts, green. 5 5 cm, simple or with few branches. 5 Leaves to 2 mm, erect and ± ap- Stems erect, to 2 cm, fastigiately pressed to the stem, oblong- branched from near base, lanceolate, widest at or slightly just proximal to the dichotomous distally. Leaves 5 5 spreading when moist, erect and middle, tapering gradually to a rather blunt apex, lamina 5 5 1-stratose except on margins; margins subentire, plane 5 somewhat contorted when dry, to narrowly recurved, ± erect near the apex, irregularly linear-lanceolate, lamina 1- 2-stratose in the distal half of the leaf; costa percurrent, stratose except on margins; margins plane proximally, erect to broad, occupying about 1/3 width of the leaf base, in section with a weakly developed stereid band on abaxial slightly incurved distally, 2-stratose and subserrulate side of guide cells; cells of proximal part of lamina distally, the apex blunt and coarsely toothed; costa broad, rectangular, thin to moderately thick-walled, becoming strong, ceasing shortly just proximal to the apex, in slightly shorter and narrower towards the leaf apex. section with strong abaxial and weak adaxial stereid Specialized asexual reproduction by rhizoidal tubers. bands; lamina cells thick-walled, rectangular proximally, Sexual condition dioicous; perichaetial leaves with a becoming ± quadrate distally. Specialized asexual sheathing base, abruptly narrowed to a short subula reproduction unknown. Sexual condition autoicous; about as long as the base or shorter. Seta yellowish, perigonia terminal on short basal or axillary branches; brown to orange-brown with age, to 2.5 cm or sometimes exterior perichaetial leaves similar to stem leaves, the longer, erect. Capsule erect and symmetric or slightly inner broadly sheathing. Seta pale yellow, to 2.5 cm, curved, brown to reddish brown, narrowly ellipsoid to erect. Capsule straight and erect or slightly curved, cylindric, 1–2 mm, smooth or indistinctly furrowed when orange-brown, dark reddish brown at the mouth, dry; operculum obliquely conic-rostrate, blunt, 0.3–0.7 elliptical, narrowed at the mouth, 2–3 mm, flattened and Ditrichum · DITRICHACEAE 455 weakly sulcate when dry; operculum conic-rostrate, to 1 Okla., Pa., S.C., Tenn., Tex., Va., Vt., W.Va., Wisc.; mm; peristome 600–800 µm, often broken, the teeth split Europe; e Asia (Japan); c Africa. to the short basal membrane, spiculose-papillose. Spores When Ditrichum pallidum is fruiting, the long, yellow 8–10 µm, appearing smooth. setae are distinctive. The slightly asymmetric capsule and Capsules mature summer (Jul–Aug). Soil, montane the long, spiculose peristome teeth are similar to those of habitats; moderate to high elevations (800–1600 m); D. difficile (Duby) Fleischer, a widespread, common Alta., B.C.; Idaho, Oreg., Wash. species occurring in Mexico, Central and South America Ditrichum montanum is apparently confined to upland as well as elsewhere throughout the world, and D. habitats on disturbed soil. It is distinguished from D. rhynchostegium. However, the spores of all three species heteromallum by the short, more or less quadrate cells in are easily distinguished. Spores of D. difficile are finely the distal part of the leaf and by the pale, yellowish seta. papillose-verrucose and 12–18(–20) µm; those of D. Elevation data are from E. Lawton (1971). rhynchostegium are vermicularly papillose-verrucose and 11–15(–18) µm; those of D. pallidum are larger, 15–30 7. Ditrichum pallidum (Hedwig) Hampe, Flora 50: 182. µm, and the exine ornamentation coarsely and openly 1867 papillose. Trichostomum pallidum Hedwig, Sp. Herbarium specimens of Ditrichum pallidum and D. Musc. Frond., 108. 1801; rhynchostegium are sometimes misidentified. If fruiting, Ditrichum currituckii Grout the orange to reddish seta of D. rhynchostegium will immediately distinguish it from D. pallidum with its Plants rather small, in silky green yellowish seta. Also, spores of D. rhynchostegium have 5 5 5 5 to yellowish green, loose to 5 5 a distinctly vermicular ornamentation and are smaller. 5 5 5 5 5 5 5 5 5 5 5 55 compact tufts. Stems short, to 5 5 5 5 5 5 The operculum of D. pallidum is about half the length of 5 5 5 5 5 5 5 5 5 0.5(–1) cm, usually simple. Leaves 5 that of D. rhynchostegium. Vegetatively, plants of D. erect-spreading to subsecund, pallidum have short stems and the leaf base is often ovate flexuose-contorted when dry, to 7 to ovate-lanceolate, being gradually narrowed to the mm; from a short ovate-lanceolate and ± sheathing base subula. On the other hand, plants of D. rhynchostegium gradually or rather shortly narrowed to an elongate have longer stems and the leaf base is oblong-ovate and subula, lamina 2-stratose distally; margins erect, abruptly narrowed to the subula. L. E. Anderson and becoming serrulate towards the apex, 1-stratose V. S. Bryan (1958) discussed the similarity of D. proximally, 2-stratose in the subula; costa rather thin and currituckii and D. pallidum, but maintained them as narrow at the base, broader distally and occupying most distinct species. H. A. Crum and Anderson (1980–1983) of the base of the subula, excurrent, in section with a considered D. currituckii to be a variant form of D. broad band of guide cells and shallow adaxial and abaxial pallidum having shorter capsules and peristomes, slightly stereid bands; cells of the leaf base rectangular to oblong- shorter leaves with the costa somewhat broader at the hexagonal, narrowed towards the margin and forming a base. The morphological and cytological differences were ± distinct hyaline zone, elongate-rectangular in distal leaf considered by Crum and Anderson (1981) to be base and subula. Specialized asexual reproduction insufficient to warrant separation. unknown. Sexual condition autoicous; perigonia axillary; perichaetial leaves shorter than stem leaves, the base not 8. Ditrichum pusillum (Hedwig) Hampe, Flora 50: 182. sheathing. Seta yellow or sometimes reddish brown near 1867 base, elongate, to 4 cm or occasionally longer, flexuose. Capsule suberect to somewhat inclined, yellow to Didymodon pusillum Hedwig, Sp. brownish yellow, reddish brown with age, subcylindric, Musc. Frond., 104. 1801; with a broadened base tapering gradually to a narrowed Ditrichum tortile (Schrader) mouth, 1–2.5 mm, slightly asymmetric, weakly furrowed Brockmuller; Trichostomum tortile

5 Schrader; T. tenue Hedwig; Weissia 5 when dry and empty; operculum conic-rostrate, to about 5 5 5 5 5 5 5 5 5 capillacea Bridel 5 5 5 5 0.8 mm; peristome 300–800 µm, pale brown to yellowish 5 5 55 5 5 5 5 5 5 5 5 5 5 5 5 5 orange, 2-fid to a very short basal membrane, densely 5 5 Plants small, to ca. 1 cm, forming 5 spiculose throughout. Calyptra long-cucullate. Spores dull green tufts. Stems 0.4–1.2 cm, rounded to obscurely tetrahedral, 15–30 µm, coarsely simple. Leaves to ca. 3.5 mm, and sparsely papillose, brown. erect-patent, weakly secund, lanceolate to linear- Capsules mature winter–summer (Feb–Jul). Sandy or lanceolate, gradually acuminate to a channelled subula, clay soil, rather dry, open or partly shaded habitats; low acute, lamina 1-stratose except on margins; margins elevations; N.B., N.S., Ont., Que.; Ala., Ark., Conn., bistratose, entire or serrulate near the apex, irregularly D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, thickened and recurved at least in distal half; costa stout, Md., Mass., Mich., Miss., Mo., N.J., N.Y., N.C., Ohio, percurrent to excurrent, in section with abaxial stereid 456 DITRICHACEAE · Ditrichum band; proximal lamina cells elongate-rectangular, distal the costa, narrower and shorter near the margins, lamina cells subquadrate to short-rectangular or becoming shorter and subquadrate to short-rectangular somewhat irregular in outline, ± incrassate. Specialized and thicker-walled in distal sheath, short-rectangular to asexual reproduction by rounded to pyriform or quadrate in the subula. Specialized asexual reproduction irregularly-shaped, yellow to orange rhizoidal tubers, to unknown. Sexual condition autoicous; perigonia axillary; 150 µm. Sexual condition dioicous; perichaetial leaves perichaetial leaves with a ± sheathing base. Seta orange- similar to stem leaves but with a somewhat longer subula yellow becoming reddish at maturity, elongate, 2–5 cm, narrowing more abruptly from the base. Seta becoming slender, flexuose. Capsule suberect to inclined, pale reddish with age, to 1.5 cm, erect. Capsule erect, dark brown, ovoid cylindric when moist, slightly asymmetric, brown to reddish brown, ovoid to cylindrical, symmetric, 2.5–3.5 mm, flattening when dry and empty, narrowed 1–2 mm, smooth to ± furrowed when dry; operculum at the mouth; operculum tall-conic, tapering to a blunt obliquely conic-rostrate, blunt, 0.3–0.7 mm; peristome apex, to 1.5 mm; peristome teeth pale brown, to 1500 split nearly to the base into 2 segments, brown, densely µm, split almost to the base into two long, filiform, and finely obliquely-ridged and lightly papillose, 200– densely spiculose filaments. Spores rounded to rounded- 250 µm. Spores 11–20 µm, appearing ± smooth. tetrahedral, 11–15(–19) µm, vermicular papillose- Capsules mature spring–summer (Apr–Jun). Bare, verrucose, yellowish brown. disturbed calcium-free clay, sandy or gravely soil banks, Capsules mature summer (Jun–Aug). Sandy or clay disturbed habitats, especially along roads and trails, and soil, clearings in woods, banks of trails, sometimes over sometimes in cliff crevices; low to moderate elevations; rocks and along streams; low elevations; N.S., P.E.I.; Ark., B.C., N.B., Nfld and Labr., N.S., Ont., P.E.I.; Ala., Ark., Ga., Ky., La,, Md., N.C., Ohio, Pa., S.C., Tenn., Va., Fla., Ga., Ill., Ind., Iowa, Ky., La., Maine, Mass., Mich., W.Va.; Asia (Japan, Korea, Taiwan). Minn., Mo., Nebr., N.Y., Tenn., Tex., Va., Wis.; Europe; The type collection of Ditrichum rhynchostegium Asia; Africa; Atlantic Islands (Iceland). appears to have been lost, but comparison of material When sterile, Ditrichum pusillum is morphologically collected from the type locality with the original very similar to D. ambiguum and D. tortuloides. When description left little doubt that it represented a distinct sporophytes are present, the dense, fine, obliquely striate species, and that D. henryi is synonymous (H. Robinson peristome teeth with weak papillae immediately 1966). Ditrichum rhynchostegium has been confused distinguish D. pusillum from those two species, which with D. pallidum but is readily distinguished from that have spiculose peristome teeth. The spores of D. pusillum species superficially and microscopically (see discussion (10–19 µm) are also larger compared to those of D. under 7. D. pallidum). The report of D. rhynchostegium ambiguum (6–11 µm) and D. tortuloides (9–13 µm). A from the District or Columbia by R. R. Ireland (1982) is discussion of the relationships of D. pusillum with both erroneous. D. ambiguum and D. tortuloides was given by R. R. Ireland and H. Robinson (2001). 10. Ditrichum schimperi (Lesquereux) Kuntze, Revis. Gen. Pl. 2: 835. 1891 9. Ditrichum rhynchostegium Kindberg, Rev. Bryol. 37: Leptotrichum schimperi Lesquereux, 14. 1910 Mem. Calif. Acad. Sci. 1: 9. 1868 Ditrichum henryi H. A. Crum & Plants in tufts or gregarious L. E. Anderson patches, yellowish green. Stems to 5

Plants in low, silky green to 5 0.6 cm, rarely to 1 cm, simple. 5

yellowish green tufts or loosely 5 Leaves crowded, erect-spreading

5 5 gregarious. Stems to 1 cm, simple. to slightly secund, ± contorted, 3–

5 5 5 Leaves to 5 mm, erect to some- 7 mm, narrow filiform-subulate 5 5 5 5 5 5 5 5 5 what flexuose and spreading, from an ovate to lanceolate base, rather crisped or contorted when lamina 2-stratose distally; margins plane to incurved, 1- dry, linear-subulate from a rather stratose proximally, 2-stratose distally in subula, entire suddenly widened, subsheathing base, subula channelled or slightly serrulate near the apex; costa broad, percurrent distally, lamina 2-stratose distally; margins erect, slightly to excurrent, occupying the width of the subula near the denticulate close to the apex, 2-stratose in the subula; apex, ca. 1/4 width of leaf at base, in cross section with an costa broad and flat, occupying ca. 1/4 of the leaf base, abaxial stereid band and a few adaxial stereids; distal percurrent, occupying most of the subula, in section with lamina cells short-rectangular, becoming elongate and a prominent abaxial and weak adaxial stereid band; cells rectangular proximally, narrower and longer towards the of the leaf base rather laxly oblong-hexagonal, wider near margins; perichaetial leaves with a sheathing base. Specialized asexual reproduction unknown. Sexual Ditrichum · DITRICHACEAE 457

DITRICHUM ° SAELANIA

condition autoicous; perigonia in small buds just 11. Ditrichum tortuloides Grout, Bryologist 30: 4. proximal to the perichaetium. Seta yellow, 1–3 cm, erect 1927 to flexuose. Capsule erect to inclined, yellowish to Plants green to yellowish green, yellowish brown, somewhat reddish brown with age, becoming brown with age, dull, in cylindric, 1.5–3 mm, weakly sulcate when dry; operculum loose to somewhat dense tufts. short-rostrate, to about 1 mm; annulus narrow, dehiscent; Stems 2–5 mm, simple or seldom peristome short, to 300 µm, the teeth irregularly perforate branched, with a few dark red or divided proximally, with a narrow basal membrane, 55 rhizoids near the base. Leaves 5 finely papillose distally, nodose proximally. Calyptra erect-spreading, slightly crisped to large, cucullate and twisted. Spores 20–30 µm, falcate-secund when dry, 1–3 mm, roughened, brown. lanceolate to linear-lanceolate, Capsules mature spring (Apr–May). Moist soil; low channelled, lamina 1-stratose except near margins; elevations; B.C.; Calif., Oreg., Wash. margins plane to narrowly recurved from just beyond L. E. Anderson and V. S. Bryan (1958) stated that the leaf base to mid leaf, serrate to strongly serrate from Ditrichum schimperi is not uncommon from Vancouver mid leaf to the acute apex, 2-stratose distally and rarely Island and south through the Coastal Ranges to Yosemite a cell inward; costa distinct, percurrent, occupying 1/6– Valley. This is the only Ditrichum species along the west 1/3 width of the leaf base; lamina cells thick-walled, distal coast of North America with large and roughened cells 8–24 × 8 µm, becoming slightly broader and longer papillose spores. Ditrichum pallidum from the eastern in the base. Specialized asexual reproduction unknown. and southern United States also has large, roughly Sexual condition dioicous. Seta orange-yellow, brownish papillose spores of similar size, but differs in peristome or reddish, 0.8–1.2 cm, erect. Capsule erect, yellow or characters. The peristome of D. schimperi is finely light brown, curved and asymmetric, 1–2(–2.5) mm, often papillose, rather than spinose- or spiculose-papillose, is swollen at the base; operculum rostrate, 0.5–0.8 mm; reduced in size, and is irregularly perforate proximally. peristome 200 µm, 2-fid, the filaments ± unequal, linear, 458 DITRICHACEAE · Ditrichum· Saelania somewhat twisted when dry, strongly papillose to Ditrichum tortuloides was synonymized by H. A. spiculose. Spores round, 9–13 µm, appearing smooth to Crum and L. E. Anderson (1981) with D. ambiguum. minutely papillose. However, R. R. Ireland and H. Robinson (2001) discussed Capsules mature spring (Jun). Primarily on serpentine reasons for distinguishing the two species. For a soils, clearings along roads; moderate elevations (ca. 400 discussion of the similarities and distinguishing m); Md., N.H., Vt. characteristics, see under 1. D. ambiguum.

4. SAELANIA Lindberg, Utkast Eur. Bladmoss., 35. 1878 · [For Anders Thiodolf Saelan, 1834–1921, Finnish botanist]

Rodney D. Seppelt

Plants tufted, glaucous bluish green or sometimes yellowish green. Stems short or reaching 1.5 cm, simple or branched; rhizoids at base, papillose or smooth. Leaves somewhat flexuose or contorted when dry, narrowly lanceolate, gradually acuminate, margins plane or narrowly recurved and entire proximally, irregularly and often doubly toothed or serrate distally; costa 1 1 1, percurrent to short-excurrent, /5– /3 width of leaf base; medial laminal cells smooth subquadrate to short-rectangular, smoth. Specialized asexual reproduction unknown. Sexual condition autoicous; perigonia terminal on well-developed branches; perichaetial leaves not differentiated. Seta yellow or yellow-brown, elongate, erect. Capsule erect and symmetric, exserted, yellow-brown, cylindric, ± longitudinally plicate when dry and empty; annulus of 2– 3 rows of large, pale cells, persistent; operculum rostrate; peristome single, teeth16, split into 2 filaments, densely papillose. Calyptra cucullate. Spores globose, finely papillose. Species 1: North America, Europe, Asia, Africa, Pacific Islands (Hawaii, New Zealand). Saelania is morphologically close to Ceratodon, but differs in having the leaves a glaucous blue-green; seta yellow to yellow-brown; capsule yellow-brown, erect, and somewhat plicate but not strongly sulcate when dry; peristome reddish brown, densely papillose, divided to near the base into two unbordered filaments; and spores greenish to yellowish brown and larger, 15–20(–22) µm. In Ceratodon the leaves are yellowish green to brownish or reddish green; seta reddish to purplish; capsules dark reddish brown to purplish, erect to inclined or horizontal, and when dry usually strongly sulcate; peristome teeth dark red, papillose, divided to near the base into 2 filiform segments with pale borders and the segments often united at the nodes; and spores yellow to greenish yellow, and smaller (10–15 µm).

1. Saelania glaucescens (Hedwig) Brotherus in J. O. with operculum to 1 mm. Spores 15–20(–22) µm, Bomansson and V. F. Brotherus, Herb. Mus. Fenn., greenish to yellow-brown. Musci, 53. 1894 Capsules mature early summer–late fall. Soil on steep Trichostomum glaucescens Hedwig, banks, particularly those protected by overhangs, frequent on roadsides, soil in sheltered rock crevices; 5 Sp. Musc. Frond., 112. 1801

5 moderate to high elevations; Greenland; Alta., B.C., 5 Leaves 1–2.5(–3.5) mm, proximal Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., Que., leaves small, the distal and 5 5 Yukon; Alaska, Ariz., Colo., Iowa, Mich., Minn., Nebr., 5 5 5 5 5 5 perichaetial leaves gradually 5 N.J., N.Y.; n Eurasia; e Asia; s Africa; Pacific Islands 5 5 5 5 5 acuminate, ± subulate from a 5 (Hawaii, New Zealand). 5 lanceolate base; costa with a single The whitish to bluish coloration of the leaves is row of guide cells, and both characteristic. Often thought to have been fungal or adaxial and abaxial stereid bands, cyanobacterial in origin, the granular or thread-like or adaxial stereid band sometimes weak or rarely absent; surface material responsible for the glaucous coloration lamina cells often irregularly 2-stratose towards the apex is a diterpene. and occasionally elsewhere. Seta to 15 mm. Capsule Trichodon · DITRICHACEAE 459 5. TRICHODON Schimper, Coroll. Bryol. Eur., 36. 1856 · [Greek trichos, hair, and odon, tooth, alluding to slender divisions of peristome]

Robert R. Ireland Jr.

Plants scattered or in loose tufts, light- to yellowish green. Stems 0.2–0.4 cm, simple; rhizoids at base, papillose. Leaves slightly contorted when dry, subulate, tubulose, base broad and sheathing; margins plane or incurved, serrate to enlarged portion of leaf base; costa percurrent to excurrent, filling distal part of subula, strongly prorulose on abaxial surface; medial laminal cells rectangular, sometimes quadrate and irregularly angled on margins, smooth or prorulose. Specialized asexual reproduction sometimes present, as smooth, round or irregularly shaped tubers on rhizoids. Sexual condition dioicous; male and female plants about the same size; perichaetial leaves not differentiated. Seta yellow to red, elongate, erect. Capsule erect to inclined, exserted, yellowish to reddish brown, cylindric, slightly curved or sometimes straight, smooth; annulus of 1–3 rows of large cells, deciduous; operculum conic to short-rostrate; peristome single, teeth 16, divided nearly to base to form two filiform segments, papillose. Calyptra cucullate. Spores globose, minutely papillose. Species 2 (1 in the flora): North America, Europe, Asia in boreal and arctic areas.

SELECTED REFERENCE Ireland, R. R. 1978. Trichodon in North America. Bryologist 81: 150–154.

1. Trichodon cylindricus (Hedwig) Schimper, Coroll. distinctive gametophytes and sporophytes should aid Bryol. Eur., 36. 1856 collectors in finding additional eastern localities. The Trichostomum cylindricum Hedwig, distinctive characters of this species include the small Sp. Musc. Frond., 107. 1801; plants, 2–4 mm high, with squarrose, subulate, acute leaves, and the slender, cylindric capsules. 5 Ditrichum cylindricum (Hedwig) 5 5 Grout 1. Seta 0.5–2.7 cm; capsule mostly inclined, mostly

5 5 5 5 slightly arcuate (sometimes straight), (0.5–)1–2 5 5 Stems axillary hairs 2 per leaf axil, 5 5 5 5 (–2.5) mm; spores 9–16 µm ...... 5 with 2 short, brown basal cells and 5 ...... 1a. Trichodon cylindricus var. cylindricus 3 elongate, hyaline distal cells. 1. Seta 0.3–1.3 cm; capsule mostly erect, straight to Leaves 1–3 mm, acute, bases weakly arcuate, (0.5–)1–1.5(–2) mm; spores 19– ovate; margins plane, serrate to 24 µm ...... 1b. Trichodon cylindricus var. oblongus serrulate in subulate part; costa percurrent, filling distal parts of the subula, strongly prorulose distally on abaxial 1a. Trichodon cylindricus (Hedwig) Schimper var. surface; median cells rectangular, 17–39 × 3–5 µm, cylindricus becoming larger at base. Specialized asexual reproduction sometimes present as yellowish brown, smooth, round Seta 0.5–2.7 cm. Capsule inclined, or irregularly shaped tubers borne on rhizoids, 65–100 rarely erect, arcuate (sometimes 5 straight), (0.5–)1–2(–2.5) mm. µm in longest dimension; perigonia and perichaetia 5 terminal. Seta orange to red, erect, straight, 0.3–2.7 cm, Spores 9–16 µm. 5 5 5 5 Capsule maturity date not 5 twisted when dry. Capsule slightly arcuate or sometimes 5 5 5 5 5 5 determined. Sandy or sometimes straight (0.5–)1–2(–2.5) × 0.2–0.5 mm; operculum 0.3– 5 0.6 mm. clay soil, open, disturbed sites, Varieties 2 (2 in the flora): North America, Eurasia. roadside banks, trails, fields; low Trichodon cylindricus has a disjunct distribution in to high elevations (30–2000 m); North America, where it is not uncommon in the Alta., B.C., N.B., Nfld. and Labr. (Nfld.), Ont., Que., northwestern part of the continent but is known from Yukon; Alaska, Calif., Idaho, Mich., Mont., Oreg., Wash.; only a few scattered localities in the eastern part. It has Europe; Asia. been collected from only a single locality each in Michigan (Keewenaw County), New Brunswick, and Ontario, and two localities each in Newfoundland and Quebec. The 460 DITRICHACEAE · Trichodon· Cleistocarpidium

TRICHODON ° CLEISTOCARPIDIUM 1b. Trichodonˆ cylindricus var. oblongus (Lindberg) Variety oblongus is an arctic taxon that differs from Podpera, Consp. Musc. Eur., 97. 1954 var. cylindricus only in the shorter setae, shorter capsules Trichodon oblongus Lindberg, that are more erect and often nearly straight, and Öfvers. Kongl. Vetensk.-Akad. Forh. somewhat larger spores. 5 21: 226. 1864; Ditrichum boreale 5 5 (R. S. Williams) Grout Seta 0.3–1.3 cm. Capsule erect, straight to weakly arcuate, (0.5–)1–1.5(–2) mm. Spores 19– 24 µm. Capsule maturity date not determined. Clay soil, exposed and disturbed sites; elevations not recorded; N.W.T., Yukon; Alaska; Europe.

6. CLEISTOCARPIDIUM Ochyra & H. Bednarek-Ochyra, Fragm. Florist. Geobot. 41: 1035. 1996 · [Greek kleistos, unopened, and karpos, fruit, alluding to indehiscent capsule without operculum]

Kwok Leung Yip

Plants loosely tufted, yellow-green. Stems 0.3–0.8 cm, simple, rhizoids sparse. Leaves loosely erect when dry, subulate from an ovate-lanceolate to narrowly obovate base, margins largely plane, entire, serrulate along the subula; costa excurrent, subula flexuose; cells 1-stratose, linear distally, laxly oblong-rhomboidal proximally; perichaetial leaves in transverse section with 6–7 Cleistocarpidium· Eccremidium · DITRICHACEAE 461 large guide cells closer to the adaxial side, two stereid bands on either side of guide cells in apical sections, but only one disconnected stereid band at leaf middle and base; laminal cells laxly oblong-rhomboidal proximally, linear distally, smooth. Sexual condition paroicous (and reportedly autoicous), antheridia naked; perichaetial leaves proximally broadly ovate, abruptly subulate. Seta short, erect. Capsule cleistocarpous, immersed, ovoid, broader at the base; stomata numerous, scattered in proximal half of the capsule. Calyptra mitraeform to cucullate, regularly 4-lobed at base. Spores globose, densely and finely papillose. Species ca. 2 (1 in the flora): North America, Europe. The calyptra of Cleistocarpidium is 4-lobed, often with a deep indention on one side. The cryptoporic stomata are confined to the proximal half of the capsule, but not restricted to the extreme base as is the case with Pleuridium. The pale, ovoid capsule may be slightly asymmetric. This genus includes Sporledera in the sense of European authors but not of Hampe.

1. Cleistocarpidium palustre (Bruch & Schimper) covering the apiculus, mitrate, shallowly 4-lobed to Ochyra & H. Bednarek-Ochyra, Fragm. Florist. Geobot. cucullate, deeply split on one side. 41: 1035. 1996 Capsules mature early summer (May–Jun). Wet soil, Phascum palustre Bruch & sandy swamps; low to moderate elevations; Del., La., Schimper, Mém. Soc. Mus. Hist. Md., Mass., N.J., N.Y., Pa., Tenn.; Europe. Nat. Strasbourg 2(CC): 2. 1835; The chromosome number is n = 7 (H. A. Crum and Astomum palustre (Bruch & L. E. Anderson 1981). Cleistocarpidium palustre (can Schimper) Hampe; Bruchia palustris be recognized easily by the extremely long subula, which is flexuose to some degree, the excurrent costa, and the 5 5 (Bruch & Schimper) Müller Hal.; 5 5 55 characteristic capsule, small rostrum, and mitrate 5 Pleuridium palustre (Bruch & 5 Schimper) Bruch & Schimper; calyptra. In transverse sections of the leaf, the two largest Sporledera palustris (Bruch & guide cells are at the center of the costa. Although an Schimper) Schimper annulus is absent in the capsule of C. palustre, a non- functional rudimentary ring is present in the rostrum Plants very small. Sexual condition paroicous (and beyond the spore sac region in C. japonicum (Deguchi, reportedly autoicous). Seta stout, pale, 0.6–1 mm, erect. Matsui & Z. Iwatsuki) K. L. Yip, which distinguishes Capsule immersed, ovoid, broadest at the base, whitish, these two taxa. The latter species was initially recognized not glossy, spore sac orange, 1–1.5 × 0.6–0.8 mm, as the former (S. Risse 1991) because of the similar strongly apiculate, stomatose in proximal half. Calyptra gametophytes.

7. ECCREMIDIUM Wilson, London J. Bot. 5: 450. 1846 · [Greek ekkremes, hanging, and -idium, diminutive, alluding to pendulous capsule]

William R. Buck

Plants scattered or in loose to compact turfs, mostly yellowish green, sometimes reddish. Stems erect, to ca. 0.5 mm, sometimes seemingly absent; simple or branched by innovations; rhizoids at base, smooth. Leaves imbricate to spreading when dry, lanceolate to ovate, acute to subulate; margins plane, entire or serrate; costa subpercurrent to excurrent, sometimes weak or absent toward insertion and in lowermost leaves, medial laminal cells rhomboidal to short-rectangular, becoming longer toward the insertion, smooth. Specialized asexual reproduction unknown. Sexual condition autoicous or dioicous, cladocarpous; perichaetial leaves sometimes differentiated. Seta short, curved at apex, rarely ± erect. Capsule pendulous and laterally emergent, rarely erect and immersed, reddish at maturity, subglobose; annulus near midurn, of 1–2 rows of small cells, persistent; operculum obtuse to apiculate; peristome none. Calyptra conic-mitrate, entire at base or crenate-lobed. Spores globose to reniform, coarsely papillose to reticulate. 462 DITRICHACEAE · Eccremidium

ECCREMIDIUM ° PLEURIDIUM

Species 6 (1 in the flora): North America, South America, Asia, Africa, Australia.

SELECTED REFERENCE Crum, H. A. 1981. Eccremidium, a genus of Ditrichaceae new to the Americas. Bryologist 84: 527–532.

1. Eccremidium floridanum H. A. Crum, Bryologist 84: Capsules mature Nov–Feb. Sandy or sometimes clay 531, figs. 1–10. 1981 soil in open, disturbed sites, often in areas that are wet Leaves loosely erect, subsecund, part of the year and quite dry other parts of the year, ca. 1 (proximal) to 1.6 (distal) fields and roadsides, thin soil over rock outcrops, around mm, longly subulate-acuminate margins of Taxodium swamps; low elevations (0–70 m); from a concave, lanceolate base; Fla., Ga; South America (Brazil). margins sharply serrate above the Eccremidium floridanum is known in the flora area shoulders; costa excurrent, filling only from the Panhandle of Florida and southern Georgia. It may well be more widespread in the Southeast but 5 the subula, often weak or absent 5 near the insertion; median cells appears to be ephemeral, and the plants often die down oblong-rhomboidal, 43–66 × 12– by early spring, prior to the arrival of most collectors. 17 µm, firm-walled, becoming larger at base. Sexual The species may be the same as the Australian and South condition paroicous. Seta stout, arcuate, ca. 1 mm. African E. exiguum (Hooker f. & Wilson) Wilson, with Capsule laterally emergent, pendulous, ca. 0.7 mm which it has much in common. In the field, American (including operculum); operculum dome-shaped, short- material looks different from Australian material; in the apiculate. Calyptra weakly prorulose near apex. Spores former the leaves of fresh plants are decidedly more subreniform, 67–100 µm, granulate-tuberculate on distal subsecund. The distinctive characters of this species face, the ornamentation becoming fused and ± ribbed on include its minute size, arcuate setae and laterally proximal face. emergent capsules dehiscent near mid urn without a peristome. Pleuridium · DITRICHACEAE 463

8. PLEURIDIUM Rabenhorst, Deutschl. Krypt.-Fl. 2(3): 79. 1848, name conserved · [Greek, pleura, side or rib, and -idium, diminutive, alluding to sporophytes often emerging laterally from perichaetium]

Kwok Leung Yip

Plants gregarious to loosely tufted, yellow-green. Stems 0.3–0.7 cm, simple or branched; rhizoids at base, smooth. Leaves erect-spreading or appressed when dry, proximal leaves linear to deltoid, distal leaves oblong to lanceolate with subulate to acuminate tips, margins plane and undifferentiated, entire to serrate or abruptly toothed; costa subpercurrent to excurrent, sometimes roughened on the abaxial surface, stereid bands one or two, guide cells centrally located, confluent with the cells of the leaf lamina; basal laminal cells quadrate-rectangular, median cells irregular, rhomboidal to trapezoidal, marginal cells slightly longer than adjacent cells; distal cells elongated. Specialized asexual reproduction by innovations and rhizoidal tubers. Sexual condition monoicous; perigonia occur proximal to perichaetium with antheridia generally naked in leaf axils (paroicous), or in small buds in axils of stem leaves (autoicous); perichaetia single, terminal on mature stem, with 3–8 perichaetial leaves similar to the distal cauline leaves. Seta short, erect or curved. Capsule cleistocarpous, erect, immersed, orange to brownish, ovoid to elliptical; stomata 4–10, superficial, restricted to base of capsule. Calyptra mostly persistent, cucullate. Spores spherical, papillose to short-spinose. Species 21 (4 in the flora): worldwide except Antarctica. Pleuridium is related to Ditrichum, as demonstrated by hybridization (L. E. Anderson 1980) and by similarities in gametophyte morphology and molecular characters (C. La Farge et al. 2000). Pleuridium is also closely related to Cleistocarpidium by the immersed cleistocarpous capsules but C. palustre has mitrate calyptras and pale whitish capsules, which are asymmetrical and stomatose to the equator. In Pleuridium, sporophytes may emerge laterally from the perichaetium, not because of an actual lateral origin or position, but owing to the curvature of a short seta (H. A. Crum and L. E. Anderson 1981), or because an innovation originated proximally and developed beyond the perichaetium (Chen P. C. et al. 1963), in some species of Archidium originally included in the genus (J. A. Snider and W. D. Margadant 1973). Rhizoidal tubers were reported for the genus by T. Arts and S. Risse (1988). The “central accessory cells” as used here are equivalent to Begleiter or hydroid cells of other authors.

SELECTED REFERENCES Bryan, V. S. 1956. Chromosomes and systematic position of the inoperculate mosses, Pleuridium and Bruchia. Amer. J. Bot. 43: 460–468. Snider, J. A. 1994b. Pleuridium. In: A. J. Sharp et al., eds. The moss flora of Mexico. Mem. New York Bot. Gard. 69: 92–95.

1. Fertile plants capitate, julaceous proximal to abruptly enlarged and spreading perichaetial leaves; sterile plants julaceous throughout, bearing short, appressed, blunt leaves; cells at shoulder of perichaetial leaves rhombic; costa in transverse section showing a single extensive abaxial stereid band and adaxial guide cells ...... 4. Pleuridium sullivantii 1. Fertile plants erect-patent proximal to gradually differentiated perichaetial leaves; sterile plants with leaves erect-patent, erect to flexuose-spreading; cells at shoulder of perichaetial leaves linear; costa in transverse section with a wider abaxial stereid band, a narrow adaxial stereid band, and central guide cells. 2. Perichaetial leaf lamina in transverse section uniformly 1-stratose at shoulder; plants autoicous, antheridia enclosed in leafy buds in axils of stem leaves ...... 3. Pleuridium subulatum 2. Perichaetial leaf lamina in transverse section at least partly 2-stratose at shoulder; plants paroicous, antheridia in axils of stem leaves naked or subtended by a membranous bract. 464 DITRICHACEAE · Pleuridium

[3. Shifted to left margin.—Ed.] 3. Shoulders of perichaetial leaves with jagged teeth; leaf lamina in transverse section 2-stratose on either side of costa, 1-stratose towards margin, plicate at the transitional area . . . . 1. Pleuridium ravenelii 3. Shoulders of perichaetial leaves uniformly serrulate but never jagged; leaf lamina in trans- verse section sporadically to completely 2-stratose leaving the margin narrow and 1-stratose, concave, plicae absent ...... 2. Pleuridium acuminatum

1. Pleuridium ravenelii Austin, Bull. Torrey Bot. Club 6: canaliculate costa, the jaggedly toothed shoulders are 142. 1877 most pronounced in outer perichaetial leaves. The spores Stem leaves erect, concave, lamina are the largest in the genus, as initially described by juxtacostally 2-stratose, becoming Austin. Early American bryologists (e.g., S. Watson in 1-stratose towards margin; W. H. Brewer et al. 1876–1880, vol. 2; C. L. Lesquereux proximal leaves minute, bract-like, and T. P. James 1884) considered P. ravenelii a taxon narrowly deltoid, acuminate, intergrading with P. acuminatum because of the intermediate leaf shape. Crum and Anderson suggested 55 5 5 0.53–0.85 × 0.15–0.25 mm, 5 5 5 5 that P. ravenelii is an extreme habitat response of P. 5 5 5 5 5 entire; distal stem leaves ovate to 5 5 5 lanceolate, acuminate to subulate, acuminatum populations along the coastal sand dunes 1.05–1.75 × 0.2–0.38 mm, entire; of eastern North America. Most specimens examined costa broad, percurrent to excurrent. Sexual condition are, indeed, from such characteristic habitats of the paroicous, antheridia naked in the distal leaf axils just southeastern Coastal Plain. An occasional specimen may proximal to the perichaetium. Perichaetial leaves oblong resemble P. acuminatum or P. subulatum in general habit. to obovate-lanceolate proximally, carinate-acuminate For instance, a specimen from Florida (Breen 2930, NY) distally, gradually narrowed to a broad, channeled to has an ovate-lanceolate leaf base with narrowly subtubulose acumen which is generally shorter than the acuminate tips and is 1-stratose in the portion of the leaf base, 1.58–2.63 × 0.43–0.58 mm, margins serrulate lamina towards the margins (and is therefore close to P. to serrate, erect to incurved distally, coarsely and subulatum), but (1) the carinate acumen (clearest in the irregularly to distinctly jaggedly toothed at shoulder; characteristic transverse section), (2) the jagged teeth at lamina plicate to pleated; basal cells oblong to leaf shoulders (usually obscure because hidden by the rectangular; median cells subquadrate to short- conduplicate costa and the plicate lamina), and (3) the rectangular; distal cells at shoulder longer, long- juxtacostally 2-stratose leaf lamina support its rhomboidal to curved linear; costa excurrent with a identification as P. ravenelii. conduplicate or canaliculate awn, broad, smooth on back, indistinct at mid leaf, confluent with the juxtacostal part 2. Pleuridium acuminatum Lindberg, Öfvers. Kongl. of lamina, filling most of the acumen; transverse section Vetensk.-Akad. Förh. 20: 406. 1863 of costa at mid leaf with adaxial guide cells and abaxial Pleuridium bakeri Cardot & stereid cells forming wide rows across the width with the Thériot; P. bakeri var. elongatum central accessory cells forming an aperture; innermost Cardot & Thériot; P. bolanderi perichaetial leaves ovate-acuminate, percurrent. Seta A. Jaeger; P. californicum Grout; 0.15–0.2 mm. Spores (32–)37.5–42.5 µm, bluntly and 5 P. stramineum Austin 5 5 5 finely papillose, yellow to orange in mass. 5 5 5 5 5 Stem leaves patent-erect, 5 5 5 5 5 Capsules mature Mar–Jun. Bare sandy soil, open 5 5 5 5 5 spreading, concave, occasionally spaces of scrub oak association; low to moderate plicate, lamina 2-stratose distally elevations; Ala., Ark., Del., Fla., Ga., La., Mass., Mo., (appearing multistratose in N.J., N.C., Okla., Pa., R.I., S.C., Tex., W.Va. extreme forms), 1-stratose at base; proximal leaves ovate The chromosome number of Pleuridium ravenelii is to deltoid, long-acuminate, 0.18–1.1 × 0.1–0.28 mm, n = 13 (North Carolina, H. A. Crum and L. E. Anderson entire proximally, serrulate distally; distal stem leaves 1981). The species is characterized by (1) plicate leaf deltoid to ovate, long-acuminate, 0.58–1.88 × 0.15–0.35 lamina (most easily observed in transverse sections), (2) mm, entire proximally, serrulate distally along the margin lamina outwardly 1-stratose but 2-stratose on either side of the acumen to serrate with anteriorly projecting cell of the costa, (3) channeled distal portion of costa, and ends on the abaxial surface of costa; costa broad, (4) coarsely toothed shoulder. Serrations of the leaf percurrent. Sexual condition paroicous, 1–2(–3) shoulder, however, vary from minimally toothed with antheridia naked or subtended by 1(–2) bracts in the distal projecting ends of marginal cells to abruptly exaggerated leaf axils proximal to the perichaetium, generally in 1–2 (“jagged shoulders,” Crum and Anderson ). Though not leaf axils per stem. Perichaetial leaves with oblong-ovate always obvious because of the plicate lamina and the to lanceolate base, gradually to abruptly narrowed to a Pleuridium · DITRICHACEAE 465 subulate to acuminate tip, 1.25–4.3 × 0.25–0.5 mm, entire proximally, infrequently serrulate distally; costa margins entire proximally, plane to incurved, entire to narrow, percurrent. Perichaetial leaves oblong-ovate, irregularly serrulate distally especially along margin of gradually narrowed to long-subulate, frequently crisped acumen, marginal cells short-rectangular to quadrate; awn, 2.25–3.43 × 0.23–0.4 mm, margins entire basal cells loosely rectangular to quadrate; median cells proximally, irregularly serrate to serrulate distally in the subquadrate to rectangular to trapezoidal; distal cells in subula; basal cells loosely rectangular; median cells acumen linear; costa percurrent, indistinctly defined, irregular, subquadrate to short-rectangular to filling the cucullate acumen; transverse section of costa rhomboidal; distal cells in subula oblong to trapezoidal; at mid leaf showing a row of central guide cells confluent costa percurrent, filling the tubulose subula; transverse with the adaxial laminal cells, a widespread abaxial band section of costa at mid leaf with central guide cells forming of stereids, a restricted adaxial group of stereids, and a a row across the width between a more restricted band few thin-walled accessory cells in the center; innermost of adaxial stereids and an extensive abaxial stereid band, perichaetial leaves long-lanceolate with an acuminate tip, accessory cells sandwiched in the center; innermost percurrent, 1.13–2.6 × 0.11–0.25 mm. Seta 0.075–0.5 perichaetial leaves ovate, more or less sheathing base and mm. Spores 20–30(–35) µm, densely papillose, light acuminate tip, subpercurrent. Specialized asexual orange-brown in mass. reproduction absent. Sexual condition autoicous, Tufts on open disturbed soil, old fields, along railways antheridia naked in persistent axillary leafy buds, one to and roads on sandy banks; low to moderate elevations; several along the distal part of stem. Seta 0.25–0.53 mm. B.C.; Ala., Ark., Calif., Ga., Kans., La., Mass., Md., Mo., Spores 25–31.3 µm, densely and finely papillose, light N.C., Ohio, Okla., Oreg., Pa., Md., N.Y., Va., Wash., orange-brown in mass. W.Va.; Europe; Asia (China); s Africa; Atlantic Islands; Tufts on wet sandy soil in roadside ditches and moist Pacific Islands (New Zealand). habitats; low to moderate elevations; B.C., N.B., N.S., The chromosome number of Pleuridium acuminatum Ont., Que.; Ala., Ark., Calif., Conn., D.C., Fla., Ga., Ill., is n = 26 (V. S. Bryan 1956; H. A. Crum and L. E. Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Anderson 1981). The species is characterized by (1) the Mo., Nebr., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Pa., paroicous sexual condition and (2) the 2-stratose leaf S.C., Tenn., Vt., Va., Wash., W.Va., Wis.; West Indies lamina at shoulder. The bolanderi and the stramineum (Puerto Rico); Europe. expressions represent intermediate variations between the The chromosome number of Pleuridium subulatum is common variant of P. acuminatum (with a sporadically n = 13 (V. S. Bryan 1956; H. A. Crum and L. E. Anderson 2-stratose lamina) and the californicum expression 1981; A. J. E. Smith and M. E. Newton 1968). It and P. (almost completely 2-stratose). W. C. Steere et al. (1954) acuminatum are morphologically similar. Pleuridium and Bryan have pointed out that the n = 26 chromosome subulatum is distinguished by its autoicous sexual count in the bolanderi expression provides evidence for condition and 1-stratose lamina at leaf shoulder. its conspecificity with P. acuminatum. The stramineum, bakeri, and elongatum expressions have long been treated 4. Pleuridium sullivantii Austin, Bull. Torrey Bot. Club as taxonomic synonyms of the bolanderi expression 6: 142. 1877 (Anderson et al. 1990; E. G. Britton 1913b; Crum et al. Stem leaves appressed, concave, 1973; A. J. Grout 1928–1940, vol. 1; E. Lawton 1971). lamina 1-stratose; proximal leaves Specialized asexual reproduction by rhizoidal tubers has minute and bract-like, deltoid, been reported. acuminate, 0.80–0.85 × 0.35–0.38 mm, entire proximally, serrulate 3. Pleuridium subulatum (Hedwig) Rabenhorst, 5 5 5 distally; distal stem leaves broadly

5 5 5 Deutschl. Krypt.-Fl. 2(3): 79. 1848 5 5 5 5 ovate-lanceolate, 0.85–1.35 × 5 5 Phascum subulatum Hedwig, Sp. Musc. 5 0.38–0.55 mm, entire proximally, Frond., 19. 1801; Pleuridium infrequently serrulate distally; alternifolium var. lancastriense Sullivant costa broad, percurrent. Perichaetial leaves obovate, & Lesquereux; P. alternifolium var. abruptly subulate with an excurrent tip, 1.2–2.2 × 0.30–

5

5 robustum Sullivant & Lesquereux 0.75 mm, margins entire proximally, erose-serrulate 5 5 5 5 5 5 5 5 5 5 5 5 5 distally especially at shoulder; basal cells loosely 5 5 5 5 5 5 5 5 55 Stem leaves patent to erect-spreading, 5 5 5 5 5 5 5 5 5 5 rectangular; median cells irregular, subquadrate to short- 5 5 concave, lamina 1-stratose through- 5 out; proximal leaves minute and rectangular to rhomboidal or trapezoidal; distal cells at bract-like, long-deltoid, subulate, shoulder shorter, rhomboidal; costa percurrent to 0.38–0.8 × 0.15–0.23 mm, entire proximally, minimally excurrent, narrower proximally, widest at shoulder, filling 1 serrulate to entire distally; distal stem leaves with oblong- the tip, which is less than /4 of the leaf length, 0.25–0.55 ovate base, apex subulate, 1.03–2.13 × 0.18–0.35 mm, mm; transverse section of costa at mid leaf showing 466 DITRICHACEAE · Pleuridium

PLEURIDIUM ° PSEUDEPHEMERUM adaxial guide cells extending across costa, an extensive misidentified as other species of Pleuridium chiefly abaxial band of stereids, and a few thin-walled accessory because the leaves may appear patent and not tightly cells in the center; innermost perichaetial leaves oblong julaceous. However, P. sullivantii is the only species in with an acuminate tip, subpercurrent. Sexual condition the flora producing (1) appressed, julaceous leaves on paroicous, antheridia naked in the stem leaf axils. Seta the stem, (2) obovate perichaetial leaves which are 0.2–0.25 mm. Spores (23–)27–33 µm, densely and finely abruptly subulate and excurrent, (3) erose-serrulate papillose-spinulose, light orange-brown in mass. margin at leaf shoulder, and (4) frequently seemingly Sandy soil in open weedy habitats, old-fields, creek stand-alone, julaceous asexual innovations. bottoms, openings in woods, disturbed roadside habitats; Pleuridium mexicanum Cardot has been recently low to moderate elevations; Ark., Conn., Fla., Kans., La., found in California. It would key to P. sullivantii but Miss., Mo., N.J., N.C., Pa., S.C., Tex., Va. differs by having entire perichaetial leaves and vermicu- A chromosome count has not been reported for lose spores. Pleuridium sullivantii. Sterile innovations are common, julaceous, solitary, to 5 mm, with leaves bract-like to oblong-acuminate. Some collections have been Pseudephemerum · DITRICHACEAE 467

9. PSEUDEPHEMERUM (Lindberg) I. Hagen, Kongel. Norske Vidensk. Selsk. Skr. (Trondheim) 1910(1): 45. 1910 · [Greek pseud-, false or resembling, and genus Ephemerum]

Kwok Leung Yip

Pleuridium sect. Pseudephemerum Lindberg, Öfvers. Kongl. Vetensk.-Akad. Förh. 21: 583. 1865

Plants gregarious to loosely tufted, yellow-green. Stem 0.04–0.2 cm, branched, rhizoids sparse. Leaf reflexed-recurved, lanceolate with sheathing base, margins serrulate at apex, occasionally to the base, doubly toothed mostly at angles acute to the long axis; costa thin and narrow, subpercurrent, serrulate abaxially, with a central stereid band, basal cells large, rectangular, distal cells rhombic, smooth. Sexual condition synoicous; antheridia in axils of leaves, becoming lateral after indeterminate growth of the stem. Seta very short, erect. Capsule cleistocarpous, immersed. Calyptra cucullate. Spores globose, papillose. This genus is placed in the Ditrichaceae because the chromosome number of n = 13 (E. Lawton 1971) is essentially that of Ditrichum, the type genus of the family. A recent study (M. Stech, unpubl.) supported the relationship between Pseudephemerum and Trichodon, both of the Ditrichaceae. Species 1: North America, Mexico, South America, Europe, Asia, Africa, Pacific Islands (New Zealand), Australia.

1. Pseudephemerum nitidum (Hedwig) Loeske, Stud. This species is readily recognized by the lax and Morph. Laubm., 75. 1910 undifferentiated leaf cells, and the serrulate leaf tips. Phascum nitidum Hedwig, Sp. Vegetatively, it is superficially similar to Pohlia, Bryum, Musc. Frond., 19. 1801; P. axillare or Leptobryum species by the thin-walled laminal cells Smith; Pleuridium axillare (Smith) and the serrated leaf apices, but the rough papillose Lindberg; P. nitidum (Hedwig) rhizoids of these genera distinguish them from 5 Rabenhorst Pseudephemerum nitidum. E. Nyholm (1986+) reported

5 asexual reproduction of P. nitidum by spherical gemmae. Stem leaves erect-spreading, Pseudephemerum nitidum is newly reported from Oregon lanceolate, to 1.8 mm at stem tip, and Mexico from similar habitats (Yip K. L. 2002). The base ovate, margins plane, entire, previous reports of this species in Canada could be serrulate at the flat apex. Seta 1 verified only from a specimen from Richmond, British (–2), short, erect. Capsule pale brown, 0.5–0.65 mm, Columbia (Schofield 22437, UBC, WTU). A Nova Scotia ovoid with a short point, smooth, exothecial cells hyaline, report could not be confirmed after re-examination of quadrate, stomata only on proximal part of capsule. the reported specimens (Yip 1998). Calyptra 0.3–0.4 mm. Capsules mature Nov. Damp soil, silt hammocks in grassy areas near river banks; low to moderate elevations; B.C.; Oreg.; Mexico; South America; Europe; Asia (Assam, Japan, Nepal); Africa (Congo, Kenya, Rwanda, Uganda, Zaire); Indian Ocean Islands (Madagascar); Pacific Islands (New Zealand); Australia (Tasmania).