BFNA Title: Imbribryum
Author: J. R. Spence
Date: January 24, 2010
Edit Level: R
Version: 2, April 14, 2010

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

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XX. IMBRIBRYUM Pedersen, Bryologist 108: 449. 2005 * [Greek imbri, imbricate, and bryum, a moss, alluding to strongly imbricate leaves]

 

John R. Spence

Plants medium-sized to robust, in open to dense turfs or gregarious on soil or rock, green, yellow-green, red-green or red. Stems 0.5--3(--4) cm, evenly foliate, innovations and fertile stem leaves somewhat differentiated, leaves of innovations smaller, stems sometimes julaceous; rhizoids sparse, at base of stem, occasionally in clusters along stem. Leaves (0.6--)1.5--2.5(--3) mm, strongly imbricate  when dry, erect when wet, flat or concave, rarely decurrent; apex obtuse to acuminate, apiculus absent; margins plane to strongly revolute, smooth to serrulate distally, limbidium absent or occasionally present, of 1--2 rows of more elongate cells; costa percurrent to short-excurrent as an awn, in cross-section generally with 1 layer of guide cells; distal and mid-laminal cells vermicular to rhomboidal or hexagonal, 6--16(--22) \um wide, mostly 3--6(--8):1, thin-walled to incrassate, rarely porose, proximal laminal cells abruptly quadrate or rectangular, 1--2(--3):1, wider and shorter than cells above, 1--2 layers of enlarged colored cells sometimes present across leaf base, inflated group of pink sub-alar cells absent. Specialized asexual reproduction by rhizoidal tubers, spherical, (100--)150--350 \um, red, red-brown, orange, or pink, on rhizoids in proximal leaf axils.  Sexual condition dioicous; perigonial and perichaetial leaves not much differentiated, outer perichaetial leaves larger, inner leaves smaller than leaves of innovations. Seta long-exserted, stout to slender, straight or somewhat flexuose. Capsule 2--6 mm, pyriform to clavate, apophysis slender, not thickened, inflated or rugose; inclined or nutant; peristome double, well developed, exostome teeth yellowish, often separate at base, endostome high, not adherent to exostome, segments well developed, with ovate perforations, cilia long and appendiculate or sometimes nodose; operculum low-conic to convex, sometimes apiculate, rarely rostrate. Spores small, smooth to papillose, 8--18(--20) \um.

Species ca. 40 (6 in the flora): Nearly worldwide in tropical, subtropical, temperate to boreal regions, rare in Arctic-alpine climates, absent from Antarctica.

Imbribryum consists of relatively large species with elongate, evenly foliate stems and strongly imbricate leaves. Species commonly grow on soil or rock, often associated with waterfalls, seeps and springs, or splashed rock. The genus is especially well represented in the mountains of New Guinea, the Neotropics, southeast Asia, and Africa. Most species produce rhizoidal tubers; the presence of leaf axil bulbils, reported from European material of I. gemmiparum, has not been confirmed for North American collections. Many species are difficult to identify as they are morphologically variable, especially I. alpinum and I. muehlenbeckii. There is one undescribed species in the western U.S., discussed under I. muehlenbeckii.

 

SELECTED REFERENCES  Whitehouse, H. L. K. 1963. Bryum riparium Hagen in the British Isles. Trans. Brit. Bryol. Soc. 4: 389--403. Ochi, H. 1980. A revision of the Neotropical Bryoideae, Part 1. J. Faculty Educ. Tottori Univ., Nat. Sci. 29: 49--154. Nyholm, E. 1993. Illustrated flora of Nordic mosses. Fasc. 3. Bryaceae-Rhodobryaceae-Mniaceae-Cinclidiaceae-Plagiomniaceae. Nordic Bryological Society. Pedersen, N. 2005. Validation of Imbribryum (Bryaceae). Bryologist 108: 449. Spence, J. R. 2007. Nomenclatural changes in the Bryaceae (Bryopsida) for North America II. Phytologia 89: 110--114. Spence, J. R. 2007. Four species of the Bryaceae new to the U.S.A. Evansia 24: 29--30. Sagar, T. and P. Wilson. 2009. Niches of common bryophytes in a semi-arid landscape. Bryologist 112: 30--41.

 

 

1. Leaves rigid, strongly imbricate when dry; distal laminal cells long, incrassate and vermicular, more than 6:1.

2. Costa percurrent to short-excurrent; limbidium absent; proximal laminal cells gradually wider proximally, short-rectangular to quadrate; capsule pyriform with short neck . . .  1. Imbribryum alpinum

2. Costa short to moderately long-excurrent into a slender awn; weak to moderately strong limbidium present; proximal laminal cells abruptly enlarged, somewhat bulging, rectangular; capsule with distinct, long neck. . . 3. Imbribryum microchaeton

1. Leaves rigid to somewhat loosely imbricate; distal lamina cells shorter, not vermicular, mostly 3--5:1.

3. Stems strongly julaceous; leaves red or purple, rarely green, strongly concave, apices rounded-obtuse to broadly acute, cucullate; costa percurrent; distal lamina cells incrassate, oblique to costa, proximal laminal cells abruptly enlarged to inflated in 1--2 rows . . . 5. Imbribryum miniatum

3. Stems not or weakly julaceous; leaves red to green or yellow, concave to flat, apices obtuse, acute, or acuminate, not cucullate; costa not reaching apex to excurrent; distal lamina cells thin to somewhat firm-walled, parallel to costa, cells at leaf base not abruptly enlarged or inflated.

4. Leaves flat or weakly concave, ovate-lanceolate, apices acute to acuminate; costa short-excurrent in slender, sometimes denticulate awn  . . . 4. Imbribryum mildeanum

4. Leaves distinctly concave, ovate, apices broadly acute or obtuse; costa not reaching apex or rarely percurrent, awn absent.

5. Leaves green to yellow-green, lacking red tints, loosely set, somewhat distant proximally along stem; proximal laminal cells short-rectangular  . . . 2. Imbribryum gemmiparum

5. Leaves red or red-green, red tints usually present, rigid and imbricate, crowded; proximal laminal cells quadrate  . . . 6. Imbribryum muehlenbeckii

 

 

1. Imbribryum alpinum (Hudson ex Withering) Pedersen, Bryologist 108: 449. 2005

 

Bryum alpinum Hudson ex Withering, Syst. Arrangem. Brit. Pl., Ed. 4, 3: 824. 1801

 

Plants medium-sized, in open to dense turfs, dark red to red-green, rarely entirely green, sometimes becoming black with age. Stems 0.5--2(--3) cm, evenly foliate, somewhat julaceous, with metallic sheen, older portions of stem sometimes densely radiculose. Leaves 1--3 mm, red to red green or sometimes green, strongly imbricate when dry, erect when wet, rigid, broadly lanceolate to narrowly ovate or lingulate or occasionally narrowly triangular, weakly concave, not decurrent; apex acute; margins plane distally, revolute proximally, smooth to finely serrulate distally, limbidium absent; costa reddish, percurrent to short-excurrent as a stout awn; distal and mid-laminal cells elongate-hexagonal to vermicular, (50--)60--80 x (8--)10--12 \um, mostly 6--8:1, strongly incrassate, parallel to costa, proximal laminal cells abruptly quadrate to short-rectangular, 1--2(--3):1, occasionally a single row of colored cell present across leaf base. Specialized asexual reproduction of red to red-brown spherical rhizoidal tubers on rhizoids arising from leaf axils, 100--300 \um, scarce. Seta 1--3 cm, stout, more or less straight, red or red-brown to purple. Capsule 3--5 mm, pyriform, short-necked, inclined to nutant, red-purple; operculum convex, apiculate. Spores smooth to papillose, yellowish, 10--15 \um.

 

Capsules rare, maturing spring--summer. Local and uncommon on moist acidic rock or soil over rock; 0--2500 m; Greenland; Nfld. & Labr.; Alaska (St. Lawrence I.), Calif., Colo., Ill., N.H.; w,n Eurasia; n Africa.

 

Imbribryum alpinum is a relatively rare boreal-temperate species characterized by narrow, shiny-metallic, red leaves and incrassate, elongate distal laminal cells.  Most reddish plants similar to this species in the western U.S. do not conform well to this set of characters.  Instead, most collections have red, broadly ovate leaves, shorter distal lamina cells, and short-excurrent costae.  This material cannot be referred to either I. alpinum or I. muehlenbeckii, and apparently represents an undescribed species. Reports from southern Africa need to be verified as other red-colored species occur in the Southern Hemisphere.

 

2. Imbribryum gemmiparum (De Notaris) J. R. Spence, Phytologia 89: 112. 2007

 

Bryum gemmiparum De Notaris, Comm. Soc. Crittog. Ital.2: 212 [112] [Cronaca Bryol. Ital. 1: 25] 1866

 

Plants medium-sized, in open to dense turfs, bright green to yellow-green near tips, becoming stramineous with age. Stems 1--2(--3) cm, evenly foliate, weakly julaceous, with or without metallic sheen, older portions of stem sometimes densely brown-radiculose. Leaves 1--3 mm, green, younger leaves sometimes yellowish, strongly imbricate when dry, erect when wet, soft, strongly concave, weakly decurrent; apex rounded to acute; margins plane throughout, rarely  revolute proximally, smooth, limbidium absent; costa not reaching apex or percurrent, brown to yellow-brown; distal and mid-laminal cells hexagonal, (30--)40--60 x (14--)16--26 \um wide, mostly 3(--4):1, thin-walled, proximal laminal cells abruptly short-rectangular, 2--3:1, occasionally with quadrate cells intermixed, single row of colored cell across leaf base absent. Specialized asexual reproduction of pink to orange spherical rhizoidal tubers on rhizoids arising from leaf axils, 100--200 \um, rare [leafy bulbils in leaf axils]. Seta 1--3 cm, stout, more or less straight, brown. Capsule 2--3 mm, pyriform, short-necked, inclined to nutant, brown; operculum convex, weakly apiculate. Spores small, smooth to papillose, yellowish, 12--18 \um.

 

Capsules rare, maturing spring--summer. Damp to wet calcareous soil or soil over rock, often associated with springs; 0--1800 m; Alta., B.C., Ont.; Alaska, Ariz., Calif., Colo.,  Idaho, Maine, Mass., Mich., Minn., Mo., Mont., Mo., Nebr., Nev., N.J., N.Mex., N.Y., Okla., Oreg., Pa.,  S.Dak., Utah, Wash, Wyo.; s Europe; Asia (Turkey); n Africa.

 

European material of Imbribryum gemmiparum is reported to produce small, leafy bulbils in leaf axils, but there is some controversy over this as they are also sometimes described as short innovations with stalks. Molecular studies show that at least some European material appears to be related to the Gemmabryum dichotomum complex.  However, North American material is much larger in size, and is otherwise morphologically closest to other Imbribryum species. Future studies may indicate that there are two species present, one in North America and the second in Europe and the Mediterranean. Our plants are typically found in strongly calcareous springs.

 

3. Imbribryum microchaeton (Hampe) J. R. Spence, Phytologia 89: 112. 2007

 

Bryum microchaeton Hampe, Ann. Sci. Nat. Bot., sér. 5, 4: 342. 1865

 

Plants medium-sized, in open to dense turfs, pale shiny green to brown-green. Stems 0.5--2(--3) cm, evenly foliate, not julaceous, with metallic sheen, older portions of stem sometimes densely radiculose. Leaves 1--3 mm, pale shiny green, becoming  brown with age, strongly imbricate when dry, erect when wet, rigid, weakly concave or flat, not decurrent; apex acute to acuminate; margins strongly revolute throughout, sometimes plane distally, smooth to finely serrulate, limbidium present, of 1--2 rows of elongate cells; costa short to moderately long-excurrent into a slender awn; distal and mid-laminal cells vermicular to elongate hexagonal, (8--)10--12 \um wide, mostly 6--8:1, strongly incrassate, proximal laminal cells abruptly enlarged, rectangular, 2--3:1, walls somewhat bulging, row of colored cells lacking across leaf base. Specialized asexual reproduction by spherical rhizoidal tubers, 100--200 \um, red or red-brown, on rhizoids on stem. Seta 1--3 cm, stout, more or less straight, brown to red-brown. Capsule 4--6, mm, elongate-clavate, with long distinct neck, inclined to nutant, brown; operculum convex, apiculate. Spores papillose, yellowish, 16--20 \um.

 

Capsules mature spring--summer. Rare on damp calcareous rock or soil over rock in protected sites; 0--500 m; Calif., Fla.; Mexico; Central America (Guatemala); South America (Argentina, Colombia).

 

Imbribryum microchaeton was recently collected in the Santa Monica Mountains of southern California (T. Sagar and P. Wilson 2009). This species is similar to I. alpinum, differing in the pale green leaves lacking any red tints, stronger costa, presence of a leaf limbidium, and long-necked clavate capsule. There is also a report from southern Florida (H. Ochi 1980); reports from Tahiti need to be verified.

 

 

4. Imbribryum mildeanum (Juratzka) J. R. Spence, Phytologia 89: 112. 2007

 

Bryum mildeanum Juratzka, Verh. Zool.-Bot. Ges. Wien. 12: 967. 1862

 

Plants small to medium-sized, in open to dense turfs, bright green, older portions of stems becoming stramineus. Stems 0.5--2(--3) cm, evenly foliate, not julaceous, lacking metallic sheen, sometimes densely radiculose. Leaves 1--3 mm, strongly imbricate when dry, erect when wet, rigid, ovate-lanceolate, weakly concave or flat, not decurrent; apex acute to acuminate; margins plane distally, revolute proximally, smooth to finely serrulate distally, limbidium absent; costa short-excurrent in slender, sometimes denticulate awn, brown, sometimes red proximally; distal and mid-laminal cells elongate-hexagonal, (30--)40--60 x (8) 10--12 \um, mostly 4--6:1, thin to firm-walled, proximal laminal cells abruptly quadrate, with a few short-rectangular cells intermixed, 1--2:1, row of colored cells across leaf base absent. Specialized asexual reproduction absent. Sporophytes unknown.

 

Damp soil along stream or in wetlands; 100--3500 m; Calif., Colo., Maine, Nev., W.Va.; w Europe, Asia (Turkey); n Africa; Atlantic Islands (Azores, Canary Islands).

 

Imbribryum mildeanum is a small, inconspicuous boreal-montane species that has been found in Maine and subalpine-alpine areas in the West. This species has generally not been recognized by North America workers, but, following the sense of European authors, the species can be confirmed from several boreal to montane sites.  It is probably more widespread than the few records indicate.

 

5. Imbribryum miniatum (Lesquereux) J. R. Spence, Phytologia 89: 112. 2007

 

Bryum miniatum Lesquereux, Mem. Calif. Acad. Sci. 1: 23. 1868

 

Plants medium-sized, in open to dense turfs, dark red to red-green, rarely green, sometimes purple-black. Stems 2--4(--5) cm, evenly foliate, strongly julaceous, with metallic sheen, older portions of stem sometimes densely radiculose. Leaves (1--)2--3 mm, purple-red to brown-red, rarely dull olive-green, strongly imbricate when dry, erect when wet, rigid, ovate, strongly concave, not or weakly decurrent; apex rounded-obtuse to broadly acute, cucullate; margins plane throughout or rarely revolute proximally, smooth to finely serrulate distally, limbidium absent; costa percurrent, red-brown to brown; distal and mid-laminal cells elongate-rhomboidal, (40--)50--60 x (10--)12--14 \um, mostly 4--6:1, strongly incrassate, arranged in rows oblique to the costa at 30--45° angle, proximal laminal cells abruptly enlarged to inflated, quadrate, with a few short-rectangular cells intermixed, 1--2:1, with 2--3 rows of somewhat inflated colored cells present across leaf base. Specialized asexual reproduction absent. Seta 1--3 cm, stout, more or less straight to flexuose, red or red-brown to purple. Capsule 2--4 (5), mm, pyriform, inclined to nutant, red-purple; operculum convex, apiculate. Spores smooth to papillose, yellow-brown, 14--18 \um.

 

Capsules common, maturing spring--summer. Common on damp to wet siliceous rock or soil over rock, often associated with waterfalls or springs; 0--1500 m; B.C., Ont.; Nfld. & Labr.; Ark., Calif., Idaho, Mo., Mont., Oreg., Pa., Wash.; Atlantic Islands (Faroes).

 

Imbribryum miniatum is a distinctive species, with dark red-purple, julaceous stems, oblique and strongly incrassate distal laminal cells, and colored inflated cells across the leaf base. Some collections from Yosemite National Park are remarkably large in stature, with dark green leaves that become nearly black when dry.  They may represent an undescribed variety or species. Imbribryum miniatum appears to be related to several Southern Hemisphere and tropical species, including Bryum crassum (Australasia), B. perconcavifolium (Mexico-Central America), B. recurvulum (southeast Asia), and B. sclerodictyon (New Guinea).

 

6. Imbribryum muehlenbeckii (Bruch & Schimper) Pedersen, Bryologist 108: 449. 2005

 

Bryum muehlenbeckii Bruch & Schimper, Bryol. Eur. 4: 163. pl. 381. 1846

 

Plants small to medium-sized, in open to dense turfs, dark red to red-green, rarely entirely green. Stems 0.5--2(--3) cm, evenly foliate, julaceous, lacking metallic sheen, older portions of stem sometimes densely radiculose. Leaves 1--2(--3) mm, dark red to red-green or sometimes dark green, strongly imbricate when dry, erect when wet, rigid, ovate, distinctly concave, not or weakly decurrent; apex rounded to broadly acute; margins plane distally, revolute proximally, smooth to finely serrulate distally, limbidium absent; costa reddish, not reaching leaf apex or rarely percurrent; distal and mid-laminal cells hexagonal, (40--)50--70 x (16--)18--24 \um, mostly (2--)3--4:1, not incrassate, parallel to costa, proximal laminal cells abruptly quadrate, with a few short-rectangular cells intermixed, 1--2:1, occasionally a single row of colored cells reaching across leaf base. Specialized asexual reproduction by orange-red to red-brown, spherical tubers on rhizoids arising from leaf axils, 100--200 \um, scarce. Seta 1--3 cm, stout, more or less straight, red or red-brown to purple. Capsule 2--3 mm, short pyriform, nutant, dark red-brown; operculum convex, apiculate. Spores small, papillose, yellow-brown, 14--18 \um.

 

Capsules rare, mature summer (June--Aug). Damp shaded siliceous rock or soil in rock crevices, montane; 500--3000 m; Greenland; B.C., Ont., Nfld. & Labr.; Calif., Idaho, Maine, Mich., Mont., Nev., N.H., N.Mex., N.Y., Oreg., Pa., Tenn., Wash.; w Europe; Asia (Caucasus); Atlantic Islands (Madiera).

 

Imbribryum muehlenbeckii is similar to small forms of I. alpinum, but has strongly concave, ovate leaves, short distal laminal cells, and a weak costa.  Most material from western North America can be referred to an undescribed species; see discussion under I. alpinum. Reports from Africa and South America need to be verified.