BFNA Title: Thuidium
Author: H. A. Crum
Date: July 1999
Edit Level: Q
Version: 1

Bryophyte Flora of North America, Provisional Publication
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XX. THUIDIUM Bruch & Schimper in P. Bruch, W. P. Schimper & W. Gümbel, Bryol. Eur. 5: 157. 1852 (fasc. 40--51 Mon. 1) * [Alluding to resemblance to branched habit of Thuja.]

 

Howard A. Crum

 

Plants usually relatively large, in dull, green to yellow-brown mats. Stems creeping to arched-ascending, 2--3-pinnate, and usually frondose; paraphyllia abundant, especially on stems, lanceolate or filiform-branched, papillose. Stem and branch leaves dimorphic. Stem leaves ovate, acuminate, generally +/- plicate at base; margins usually revolute to the base of the acumen; margins papillose-serrulate proximally, often serrulate distally by projecting cell ends; costa ending before the apex; cells mostly +/- uniform throughout, rounded- to oblong-hexagonal, thick-walled, coarsely 1-papillose at back (or less commonly with low, forked papillae and appearing to be pluripapillose). Primary branch leaves often rather similar to stem leaves but shorter. Secondary and tertiary branch leaves much smaller, concave, ovate, acute, with erect margins and usually ending in a truncate, pluripapillose cell; costa shorter and weaker. Sexual condition dioicous.  Perichaetial leaves +/- elongate, erect, pale, lanceolate or ovate-         lanceolate, long-acuminate, sometimes ciliate-margined; costa ending near the apex; cells elongate, smooth or somewhat papillose. Seta elongate, smooth or rarely papillose. Capsule inclined to horizontal, curved-cylindric, asymmetric, smooth; annulus of 2--4 irregular layers of small cells, often tardily deciduous; operculum conic or rostrate from a         convex-conic base; stomata present in the short neck; peristome teeth yellow, yellow-brown, or red-brown, densely cross-striolate basally; endostome consisting of a high basal membrane, keeled segments, and nodulose cilia in groups of 2--4. Calyptra cucullate, smooth, naked. 

 

Species 229 (4 in the flora); almost worldwide.

 

SELECTED REFERENCES Buck, W. R. and H. A. Crum. 1990. An  evaluation of familial limits among the genera traditionally aligned with the Thuidiaceae and Leskeaceae. Contr. Univ. Mich. Herb. 17: 55--69. Crum, H. & L. E. Anderson. 1981. Mosses of Eastern North America. Vol. 2, pp. 894--911. New York.

 

Thuidium is characterized by abundant, 2--3-pinnate branching paraphyllia; dioicous sexuality; dimorphic stem and branch leaves with short, thick-walled cells that are papillose abaxially and nearly always 1-papillose; 3-celled axillary hairs with a single, short, brown basal cell and two elongate, hyaline ones; terminal cells of branch leaves mostly truncate and pluripapillose; and setae nearly always smooth .  The genus is treated here in a sense exclusive of Abietinella, Rauiella, and Cyrto-hypnum (cf. W. R. Buck and H. A. Crum 1990). Abietinella is relatively robust and has 1-pinnate branching, abundant paraphyllia, dioicous inflorescences, leaf cells 1-papillose on both surfaces, and 3-4-celled, brown axillary hairs. Rauiella and Cyrto-hypnum are small plants with autoicous inflorescences, paraphyllia short and not much branched, and leaf cells papillose on both surfaces (most commonly pluripapillose). Rauiella has 1-pinnate branching, 3-celled axillary hairs, leaves not incurved when dry, strongly bulging leaf cells, and smooth setae. Cyrto-hypnum has mostly 2-pinnate branching, as well as 2-celled axillary hairs, leaves incurved when dry, leaf cells plane, and setae often roughened.        

 

1. Branching mostly 3-pinnate; terminal cells of branch leaves acute, smooth. . . . . 1. Thuidium tamariscanum

1. Branching mostly 2-pinnate; terminal cells of branch leaves truncate and plurpapillose.

2. Stem leaves incurved at base and spreading at the tips when dry, distinctly plicate; costa nearly filling the acumen; paraphylla papillose at cell ends. . . . 2. Thuidium recognitum

2. Stem leaves ± erect, less markedly plicate; costa not filling the acumen; paraphylla papillose at cell midpoints.

3. Stem leaves short-pointed, with plane margins or sometimes revolute at base; cells with low, forked papillae and appearing 1--3-papillose. . . . 3. Thuidium allenii

3. Stem leaves acuminate, revolute-margined; cells coarsely 1-papillose, sometimes forked but not appearing pluripapillose. . . 4. Thuidium delicatulum

 

 

1. Thuidium tamariscinum (Hedwig) Bruch & Schimper in P. Bruch, W. P. Schimper & W. Gümbel, Bryol. Eur. 5: 163 (fasc. 49--51 Mon. 7. 2, 3). 1852

 

Hypnum tamariscinum Hedwig, Sp. Musc. Frond., 261. 1801

 

Plants vivid-green to yellowish. Stems up to 15 cm, creeping or arched, (2--)3-pinnately branched and frondose; paraphyllia papillose near the middle of cells. Stem leaves loosely erect when dry, erect-spreading when moist, 1.5--2 mm, broadly ovate, gradually to rather abruptly acuminate, plicate; margins revolute to the base of the acumen, denticulate distally; costa strong, ending near the leaf apex; cells rounded to elliptic, thick-walled, 13--20 x 8--10 \um, stoutly 1-papillose. Branch leaves ending in a sharp, smooth cell. Primary branch leaves somewhat resembling stem leaves, ca. 0.8 mm, 2-plicate; margins somewhat recurved proximally; costa delicate, ending before the apex. Secondary and tertiary branch leaves to about 0.4 mm, ovate, acute, with erect margins and a weak costa ending near leaf middle; cells stoutly 1-papillose, the papillae +/- curved.  Perichaetial leaves pale yellow, ca. 3 mm, oblong-lanceolate, long-subulate, serrate distally, long-ciliate proximally; costa ending in the subula. Seta 25--45 mm. Capsule 3--4 mm; operculum 1.8 mm, obliquely long-rostrate; cilia of endostome 3--4. Spores ca. 12 \um, smooth or very finely papillose.

 

Moist soil or soil over rocks, sometimes in stream beds; Nfld.; West Indies (Jamaica); Europe; Asia (e Russia in Sakhalin, Japan).

 

Thuidium tamariscinum is a woodland species of relatively large and elegantly frondose plants. The branching is typically tripinnate, but it is sometimes bipinnate or imperfectly tripinnate. The leaf cells are stoutly 1-papillose, except that the terminal cell of branch leaves is sharp and smooth.

 

2. Thuidium recognitum (Hedwig) Lindberg, Not. Sällsk. F. Fl. Förh. 13: 416. 1874

 

Hypnum recognitum J. Hedwig, Sp. Musc. Frond., 261. 1801; H. protensum Michaux

 

Plants in light-green to yellowish or brownish mats. Stems 4--9 cm, 2-pinnately branched and frondose; paraphyllia papillose mostly at or near cell ends, the terminal cell usually with 2--3 large, divergent papillae. Stem leaves spreading with reflexed tips when moist, +/- incurved at base and wide-spreading at the tips when dry, ca. 1 mm, broadly ovate, abruptly acuminate, distinctly plicate; margins papillose-serrulate, more strongly so in the acumen, plane at least when removed from the stem, rarely +/- revolute proximally; costa broadened distally, nearly filling the acumen but disappearing near the apex; distal cells to 24 x 8--10 \um, rhombic to oblong-rhombic, coarsely 1-papillose. Branch leaves ending in a truncate, pluripapillose cell. Primary branch leaves smaller, with a shorter costa. Secondary branch leaveses ca. 0.2 mm, erect-spreading when wet or dry, ovate, acute; costa 1/3--2/3 the leaf length; distal cells rhombic, 8--12 x 8--10 \um, thick-walled, stoutly 1-papillose, the papillae somewhat curved, the terminal cell truncate, pluripapillose. Perichaetial leaves up to 4.2 mm; margins denticulate, sometimes dentate or notched near base of the acumen. Seta 20--42 mm, reddish. Capsule 2--3.5 mm; operculum 0.7--1 mm, high-conic or bluntly short-rostrate; cilia of endostome in 2's and 3's. Spores 11--16 \um, smooth or nearly so.

 

Moist soil, humus, or rocks, infrequently on logs or bark at base of trees, calcareous habitats, woodlands, often in clearings and timber trails; Alta., B.C., Man., Ont., Que.; Alaska, D.C., Ga., Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Y., Ohio, Okla., Oreg., Pa., Tenn., Vt., Va., Wash., W.Va., Wis.; Europe.

 

The specific epithet of Thuidium recognitum was applied by Hedwig because he recognized the many differences that separate the species from T. delicatulum: stem leaves that are shortly, broadly, and abruptly acuminate and plicate, with margins plane or nearly so; and costa spreading out and nearly filling the acumen; tips of the stem leaves wide-spreading from an arched and incurved base; perichaetial leaves eciliate; paraphyllia papillose at or near cell ends; and operculum not or only shortly and bluntly rostrate.

 

3. Thuidium allenii Austin, Bull. Torrey Bot. Club 7: 16. 1880

 

Thuidium glaucinum var. ludovicianum Cardot, Bryologist 8: 51. 1905

 

Plants slender, light-green or yellow. Stems loosely branched, irregularly to regularly 2-pinnate, loosely foliate; paraphyllia papillose at the side of cells. Stem leaves erect-spreading when moist, loosely erect or slightly incurved when dry, ca. 1 mm, ovate, broadly short-pointed, acute, not or somewhat plicate; margins +/- denticulate all around because of projecting cell ends, plane or sometimes reflexed near the base; costa ending near the apex; distal cells hexagonal, mostly about 7 \um, moderately thick-walled, 1-papillose, the papillae low and usually forked thus appearing to be 1--3 per cell.  Branch leaves ending in a truncate, pluripapillose cell. Primary branch leaves strongly incurved, 0.5--0.6 mm, ovate, acute; costa 8/10--9/10 the leaf length; cells 8--9 \um. Secondary branch leaves similar to those of primary branches but smaller, 0.2--0.4 mm, acute or obtuse; costa 7/10--8/10 the leaf length. Perichaetial leaves eciliate. Seta 25--30 mm. Capsule ca. 2.5 mm; operculum bluntly conic. Spores not seen.

 

Uncommon, soil, logs, exposed roots, tree bases in swamps, often just above water line, characteristically in Taxodium-Nyssa-Chamaecyparis swamps; Ala., Ark., Conn., Del., Fla., Ga., Ind., La., Md., Mass., Miss., N.Y., N.C., Pa., Tenn., Tex., Va. 

 

Thuidium allenii is essentially restricted to the Atlantic and Gulf Coastal Plains and the Mississippi Embayment. This species is slender, and loosely, sometimes irregularly         2-pinnate. It could easily be taken for a depauperate expression of Thuidium delicatulum. However, it is smaller and has short-pointed stem leaves with margins plane or nearly so and the branch leaves are noticeably incurved. The leaf cells are adorned with very low papillae that are generally forked so that the cells commonly appear in surface view to be 2(--3)-papillose .

 

4. Thuidium delicatulum (Hedwig) Bruch & Schimper in P. Bruch, W. P. Schimper & W. Gümbel, Bryol. Eur. 5: 164, fig. 484. (fasc. 49--51 Mon. 8, fig. 4). 1852

 

Hypnum delicatulum Hedwig, Sp. Musc. Frond., 160. 1801; Thuidium recognitum var. delicatulum (Hedwig) Warnstorf

 

Plants green or yellowish. Stems 3--8 cm, 2--3-pinnate, ± frondose; paraphyllia mostly papillose at cell points. Stem leaves erect-spreading when moist, appressed when dry, 0.6--1.5 mm, triangular-ovate, gradually or abruptly narrowed to a broad acumen or ending in a hyaline point of 2--8 1-seriate cells, not plicate; margins papillose-serrulate, revolute from the insertion to the acumen; costa ending well before the apex; distal cells irregularly oblong-hexagonal, 6--10 x 8--12 \um, rhombic, moderately thick-walled, coarsely 1-papillose. Branch leaves ending in a truncate, pluripapillose cell. Primary branch leaves erect-spreading, to 0.5 mm, acute; costa 1/2--2/3 the leaf length; cells 6--8 x 8--12 \um, rhombic, coarsely 1-papillose, the papillae curved, sometimes forked. Secondary branch leaves similar but smaller. Perichaetial leaves to 5 mm, eciliate to ciliate proximally, often denticulate distally. Seta 15--45 mm. Capsule 1.8--4 mm; operculum 0.7--2 mm, long-rostrate; cilia of endostome in 2's and 3's. Spores 12--24 \um, smooth.

 

Common in woodlands, soil, humus, rocks, logs, and stumps, infrequently bases of trees; Alta., B.C., Man., N.B., Nfld., N.S., Ont., Que., Yukon; Ala., Alaska, Ariz., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky, La., Maine, Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Vt., Va., W.Va., Wis.; Mexico; Central America; n South America; Europe; Asia.

 

Thuidium delicatulum, needlessly confused with T. recognitum, can be recognized by stem leaves erect or erect-spreading when moist, not plicate and rather gradually acuminate, with margins recurved to the base of the acumen and costa ending well before the apex. The paraphyllia have small papillae along the cell midpoints. The leaf cells are stoutly 1-papillose, but often, especially in the South, the papillae are forked. The operculum is long-rostrate .

 

1. Stem leaves merely acute; perichaetial leaves ciliate. . . 4a. Thuidium delicatulum var. delicatulum

1. Stem leaf apex extending by 2--8 hyaline cells in a single row; perichaetial leaves not ciliate or rarely ± so. . . . 4b. Thuidium delicatulum var. radicans

 

4a. Thuidium delicatulum var. delicatulum

 

Stem leaves somewhat shorter, 0.6--1.4 mm, averaging 0.9 mm, acute and not ending in a hyaline point 1-seriate cells. Perichaetial leaves ciliate proximally, denticulate distally.

 

Common in woodlands, soil, humus, rocks, logs, and stumps, infrequently bases of trees; N.B., N.S., Ont., Que.; Ala., Ariz., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky, La., Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis.; Mexico; Central America; n South America; Europe.

 

Thuidium delicatulum var. delicaulum is apparently more often in acid substrates than is T. recognitum and T. delicatulum var. radicans.  The perichaetial leaves are copiously ciliate.

 

4b. Thuidium delicatulum var. radicans (Kindberg) H. A. Crum, Steere & L. E. Anderson, Bryologist 68: 434. 1966 (1965)

 

Thuidium recognitum var. radicans Kindberg, Rev. Bryol. 19: 103. 892; T. philibertii  Limpricht; T. recognitum ssp. philibertii (Limpricht) Dixon

 

Stem leaves somewhat longer, 1--1.5 mm, averaging 1.2 mm, ending in a hyaline point of 2--8 cells in 1 row. Perichaetial leaves usually not ciliate but sometimes sparsely so, rarely copiously ciliate.

 

Apparently a calciphile, soil, humus, rocks, or logs in swampy places; Alta., B.C., Ont., Man., Nfld., N.S., Yukon; Alaska, Iowa, Maine, Mich., Minn., N.J., N.Mex., N.Y., S.C., S.Dak., Va., Wis.; Mexico; South America (Peru); Europe; Asia.

 

The var. radicans Intergrades with the var. delicatulum. The annulus of the var. radicans is of 2--3 rows of cells scarcely differentiated from suboral cells and is sometimes of aid in distinguishing this variety from var. delicatulum.