BFNA Title: Metzgeriaceae
Date: Sept. 24, 2019
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Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden
BFNA Web site: http://www.mobot.org/plantscience/BFNA/bfnamenu.htm

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XX. METZGERIACEAE H. Klinggraff

 

Vadim Bakalin

 

 

Substrate terrestrial. Thallus bright green, unlobed, unistratose except for a sharply well-defined, cordlike midrib. Branching dichotomous and with branches from underside of midrib, without strong internal cell differentiation, underside of thallus without scales, without Nostoc colonies. Specialized asexual reproduction by discoid, unistratose gemmae often present, endogenous, from thallus margins, rarely on dorsal side of the thallus and the midrib. Sexual condition dioicous or autoicous, gametangia on short ventral branches.  Sporophyte protected by a massive calyptra. Capsule short ovoid to subglobose, wall bistratose. Spores unicellular, walls thin, delicate.        

 

Genera 4, species ca. 100 (4 genera, 2 in the flora): North America, Central America, South America, Eurasia, Africa, Australia, Oceania, Antarctica.

 

Metzgeriaceae is a family that easily to recognize in regional flora because of unistratose well-developed wings, well-defined midrib and hairs commonly present along thallus margin. The most of members tend to be abundant from the temperate area and southward, although some representatives (Metzgeria furcata, Apometzgeria pubescens) freely penetrate to the boreal zone (and the corresponding belt in the mountains) and even reach the subarctic, where, however, they are rarities.

 

1. Lateral wings densely hairy both dorsally and ventrally … 1. Apometzgeria, p. XXX

1. Lateral wings naked dorsally and ventrally or sporadically to densely hairy ventrally and naked to very sporadically hairy dorsally … 2. Metzgeria, p. XXX

 

                                                                                                                                                                                               

 

1. APOMETZGERIA Kuwahara, Rev. Bryol., n.s., 34: 212. 1966 * [Greek apo, from, and hepatic genus Metzgeria]

 

Metzgeria subgen. Apometzgeria (Kuwahara) R.M. Schuster  

 

Plants pale yellow green to whitish green and deep green, when dry grayish and glossy, loosely prostrate. Thalli flattened to convex, linear, elongate. Costa (5--)8--12(--17) cells wide dorsally and (4--6--)7--12(--15) cells ventrally, biconvex, commonly with tapered, mostly sharp hairs ca. 70--120 \um. Lateral wings 17--25(--45) cells wide, dense with hairs both dorsally and ventrally or only sparingly hairy ventrally; hairs on lamina margins mostly single, but sometimes in pairs and (rarely) in groups of 3, hairs straight, stiff and short, to 90--200(--300) \um. Laminal cells ca. 30--45 x 20--30 \um, often subisodiametric, thin-walled. Specialized asexual reproduction absent. Sexual condition dioicous. Androecial branch short, ventral, subspheric, vein distinct, margins strongly incurved, 3--6 antheridia per branch. Gynoecial branch obovate, strongly hairy on both sides, with 5--10 archegonia per branch. Seta in cross section with 25--32 rows of epidermal cells, ca. 8--10(--11) cells in diameter. Capsule subspheric to shortly elliptic. Elaters 120--700 x 6--8 \um. Spores 19--23 \um, brownish.

 

Species 2 (1 in the flora): North America, South America, Eurasia.

 

SELECTED REFERENCES  Costa, D. P. 2008. Metzgeriaceae (Hepaticae). Flora Neotropica Monograph 102. New York. Doyle, W. T. and R. E. Stotler. 2006. Contribution toward a bryoflora of California III. Keys and annotated species. Catalogue for Liverworts and Hornworts. Madroño. 53: 89--197.  Schuster R. M. 1992. The Hepaticae and Anthocerotae of North America. Vol. 5. Field Museum of Natural History, Chicago.

 

 

1. Apometzgeria pubescens (Schrank) Kuwahara, Rev. Bryol. Lichénol., 34: 214. 1966

 

Jungermannia pubescens Schrank,, Prim. Fl. Salisb., 231. 1792;  Metzgeria pubescens (Schrank) Raddi

 

Plants with the ultimate segments somewhat ascending, densely hairy on both dorsal and ventral sides. Thalli ca. 15--30(--55) x 0.8--1.5 mm, irregularly pinnately branched, ventral branches virtually absent; margins not incurved. Calyptra clavate, pyriform, copiously hairy-setose, 5--9-stratose.

 

Basic to acidic rocks, decaying wood, stumps and base of living trees, mostly in forested areas; 0--1500 m; B.C., Que., Yukon; Alaska, Idaho, Maine, Mont., N.H., N.Y., N.C., Oreg., Tenn., Vt., Wash.; South America; Eurasia.

 

 

2. METZGERIA Raddi, Jungermanniogr. Etrusca, 34 1818 * [For Johann Metzger, 1771--1844, engraver]

 

Plants yellow green to greenish, deep green, or blue, loosely prostrate to ascending (especially in tapered attenuate gemmiparous shoot tips), ultimate segments sometimes ascending. Thalli plane or more commonly convex to almost tubular due to strongly recurved margins, linear, ca. 15--120 mm in length and 0.4--2 mm wide, irregularly pinnately branched, ventral innovations branches absent to common. Costa 2--6 cells wide dorsally and 2--6 cells wide ventrally, biconvex, commonly bearing hairs on ventral side, hairs with more or less obtuse tips. Lateral wings 8--30 cells wide, smooth, or with scattered (never dense) hairs on ventral surface, dorsal side without hairs; hairs of lamina margins solitary or 2(--4) arising from one point, with more or less obtuse tips. Specialized asexual reproduction by gemmae common to absent. Sexual condition dioicous or autoicous. Androecia on short ventral branches with margins strongly incurved, thus branches ± spherical; outer surface of branch smooth, inner surface smooth or hairy. Gynoecia on short obovate ventral branches, commonly hairy in outer surface, perianth and pseudoperianth absent, with 5--10 archegonia per branch; calyptra clavate, pyriform, hairy. Seta in cross section with 11--18 rows of epidermal cells, ca. 4--6(--8) cells in diameter. Capsule subspherical to shortly elliptic. Elaters 120--700 x 6--8 \um. Spores 19--23 \um, brownish.

 

Species ca. 100 (9 in the flora): North America, Central America, South America, Eurasia, Africa, Australia, Oceania, Antarctica.

 

SELECTED REFERENCES  Fuselier, L., P. G. Davison, M. Clements, B. Shaw, N. Devos, J. Heinrichs, J. Hentschel, M. Sabovljevic, P. Szoveny, S. Schuette, W. Hofbauer, and A. J. Shaw.  2009.  Phylogeographic analyses reveal distinct lineages of the liverworts Metzgeria furcata (L.) Dumort. and Metzgeria conjugata Lindb. (Metzgeriaceae) in Europe and North America.  Biol. J. Linnean Soc. 98: 745--756. Doyle, W. T. and R. E. Stotler. 2006. Contribution toward a bryoflora of California III. Keys and annotated species. Catalogue for Liverworts and Hornworts. Madroño. 53: 89--197.  Schuster, R.M. 1992. Hepaticae and Anthocerotae of North America. Vol. 5. Field Museum of Natural History, Chicago.

 

1. Marginal thallus hairs falcate or hooked, costa 2(-3) cells wide ventrally.

2. Marginal thallus hairs mostly or exclusively in pairs, strongly falcate. Thallus margin strongly recurved (i.e. curved towards the ventral side); widespread south of 55°N … 4. Metzgeria leptoneura

2. Marginal thallus hairs exclusively solitary, straight but suddenly hooked near apex.  Thallus margin plane or loosely recurved; southeastern U.S.A. … 9. Metzgeria uncigera

1. Marginal thallus hairs straight, costa 2--6 cells wide ventrally.

3. Marginal thallus hairs mostly in pairs.

4. Some marginal thallus hairs arising in groups of 3(--4) from one point; gemmae usually present; plants dioicous, commonly sterile … 6. Metzgeria myriopoda

4. Marginal thallus hairs never arising more than two from one point; gemmae not seen; plants autoicous, commonly fertile.

5. Ventral face of midrib usually 3--4 cells wide; cells of unistratose wings ca. (40--)50--65 x 35--45 \um; thallus 1.2--1.7(--2) mm wide. … 1. Metzgeria conjugata

5. Ventral face of midrib usually 2(--3) cell wide; cells of unistratose wings 30--35 x 25--37 \um; thallus 0.6--1 mm wide … 5. Metzgeria lindbergii

3. Marginal thallus hairs always solitary

6. Gemmae common, only present on dorsal side of costa and thallus wings  ... 2. Metzgeria crassipilis

6. Gemmae absent or present in thallus margins, or rarely on dorsal and/or ventral sides of costa.

7. Gemmae always present, restricted distally on tapered attenuated branch tips, where distributed on both lateral margins of thallus and ventral side of costa … 8. Metzgeria temperata

7. Gemmae commonly present, developed only on margins of thallus at some distance from apex, attenuated tapered ascending branches never developed.

8. Costa 3--5 cells wide ventrally, commonly hairy ventrally and sporadically haired dorsally; lamina cells 42--55 x 32--45 \um. Only female plants known; high elevations in the southern Appalachians … 7. Metzgeria setigera

8. Costa 2(--3) cells wide ventrally, very sporadically hairy ventrally, naked dorsally; lamina cells subisodiametric, ca. 25--35 \um in diameter; male or sterile, widespread in North America. … 3. Metzgeria furcata

 

 

1. Metzgeria conjugata Lindberg, Acta Soc. Sci. Fenn., 10: 495. 1875

 

Plants pale yellow-green to pure green, scarcely shiny to dull. Thalli ca. 10--30 x 1.2--1.7(2.0) mm, moderately convex dorsally, margins distinctly but not strongly recurved; branching predominately dichotomous, ventral  branches uncommon. Costa 100--150 \um wide, 2 large cells (45--50 \um) wide dorsally and 3--4 cells wide ventrally; ventral surface of costa convex, bearing hairs. Wings 10--20 cells wide, naked dorsally, but with some hairs occurring ventrally; hairs of margins straight, mostly paired, but in weakly developed individuals many may be solitary and only a few in pairs. Lamina cells ca. (40--)50--65 x (33--)36--45(--48) \um, often subisodiametric. Gemmae absent [or very rare]. Sexual condition autoicous, plants mostly fertile. Male and female branches usually close together on the same thallus branch. Androecial branches transversely subglobose, naked. Gynoecial branches obcordate, notched at apex, ventral face hairy. Calyptra up to 800 \um long, densely bristly. Capsule epidermal cells mostly (45--)60--100 x 15 \um, with nodular thickenings on vertical walls; inner cells ca. 36--42 x 17--20 \um, with nodular to semiannular thickenings on vertical walls. Elaters unispiral, flexuous, 450--500 x 5--7 \um, reddish brown. Spores yellowish brown, translucent, finely papillose, (16--)18--20(--25) \um.

 

Bark (mostly conifers) and rocks in more or less damp and humid sites; 0—500 m; Ont., Que.; Ark., Conn., D.C., Ky., Md., Mass., Mo., N.H., N.J., N.Mex., N.Y., N.C., Pa., R.I., S.C., Tenn., Vt., Va., W.Va.; Central America, South America, Eurasia, Africa, Oceania.

 

2. Metzgeria crassipilis (Lindberg) A. Evans, Rhodora 11: 188. 1909

Metzgeria furcata subsp. crassipilis Lindberg, Acta Soc. Fauna Fl. Fenn., 1(2): 42. 1877 [1878]

 

Plants bright- to deep green and yellow green, loosely prostrate, ultimate segments somewhat ascending; robust but soft-textured, hardly pellucid. Thalli ca. 1.2--1.7 mm wide, plane to moderately convex, margins commonly recurved, branching predominately dichotomous, ventral branches rare except for gametangial branches. Costa 100--130 \um wide, (2--)3--4(--5) cells wide dorsally and (3--)4--7(--8) cells wide ventrally; ventral surface of costa convex, commonly bearing hairs averaging 100--180 \um in length. Wings (18--)20--25(--35) cells wide, naked dorsally, but with hairs occurring ventrally. Lamina cells ca. 33--38 x 30--35 \um, often subisodiametric, thin-walled, cells chlorophyllose and opaque. Gemmae freely produced on dorsal surface of lamina, not crowded ca. 150--280 \um in diameter (ca. 6--10 cells wide) at time of abscission. Sexual condition dioicous. Androecial branches smooth subglobose. Gynoecial branches sparingly setose or pilose along the margin and occasionally developing a very few short surface cilia. Sporophyte unknown.

 

More or less dry and exposed ledges, bark and boulders in xerophytic forests; 0--1300m; N.S.; Ark., Conn., Ga., Ky., Mass., N.Y., N.C., Pa., Tenn., Vt., Va., W.Va.; South America, e Asia.

 

3. Metzgeria furcata (Linnaeus) Corda, Naturalientausch 12: 654. 1829

Jungermannia furcata Linnaeus, Sp. Plant., 1136. 1753.

 

Plants yellow green, loosely prostrate, ultimate segments somewhat ascending. Thalli ca. 5--25 x 0.3--0.85 mm (rarely up 1.2 mm wide), plane with loosely recurved margins, branching partly dichotomous, ventral branches common or virtually absent in some forms (var. ulvula). Costa 100--130 \um wide, 2--3 cells wide dorsally (cells ca. 35--42 \um x15--20 \um) and 2(--3) cells wide ventrally; ventral surface of costa convex, commonly bearing hairs averaging 80--130 \um in length. Wings 5--20 cells wide, naked dorsally and commonly ventrally (rarely very sporadically hairy ventrally); hairs on lamina margins mostly solitary, sometimes very sparse in shade forms, hairs straight, stiff and short, up 90--200(--300) \um in length. Lamina cells ca. 25--35 \um in diameter, subisodiametric. Gemmae freely produced or absent in some forms, not crowded, along thallus margins at some distance from apex. Sexual condition dioicous. Androecial branches button-shaped, naked. Gynoecial branches adaxially concave, cordate, short (up to 140--150 \um long), densely hairy ventrally with hairs ca. 125--150 \um, straight to arched. Capsule ovoid. Elaters 5.5--7.5(--10) \um wide. Spores (18--)23--28(--30) \um.

 

Varieties 3 (2 in the flora): North America, Eurasia.

 

Metzgeria furcata is sterile through most of its range in North America.  Fertile specimens have been seen only from the southern Appalachians and the northern part of the Pacific coast. Metzgeria furcata var. furcata is excluded from the flora. This species is mostly sterile, fertile plants have been found in southern Appalachians and northern part of Pacific coast. The shoot calyptra is clavate, and copiously hairy-setose.

 

1. Thalli copiously gemmiparous, ventral branches lacking or exceptionally rare; known in North America from sterile collections only; widespread in eastern North America and Alaska … 3b. Metzgeria furcata var. ulvula

1. Thalli without gemmae, ventral branches present; only male plants known; restricted to Virginia …3a. Metzgeria furcata var. decipiens

 

3a. Metzgeria furcata var. decipiens C. Massalongo, Nuovo Giorn. Bot. Ital., 17: 256. 1885

Metzgeria decipiens (C. Massalongo) Schiffner Forschungsr. Gazelle 4: 43. 1890

 

Branching terminal and ventral. Gemmae unknown. Only male plants known.

 

Sandstone ledge in shady forest; moderate elevations; Va.; poorly known (type from South America).

 

3b. Metzgeria furcata var. ulvula Nees, Naturg. Eur. Leberm. 3: 489. 1838

 

Branching exclusively terminal. Gemmae copious on margin of thallus.  Gametangia never collected.

 

Shaded bark, cliffs and humic soil in different types of forest, but presumable lighted; low and moderate elevations; N.S., Ont., Que., Ala.; Alaska, Ark., Conn., Ga., Ky., Maine, Md., Mass., Mich., N.H., N.Y., N.C., Ohio, Okla., Pa., Vt., Va., W.Va.; Eurasia.

 

4. Metzgeria leptoneura Spruce, Trans. & Proc. Bot. Soc. Edinburgh, 15: 555. 1885

 

Plants pale yellow-green, loosely prostrate in thin patches, but in wet places frequently suberect and sometimes deep green in these conditions. Thalli ca. 15--60 x 1.2--2.2 mm, strongly convex dorsally, margins conspicuously deflexed to revolute; linear, elongate, dichotomous and ventral branches common. Costa 90--120 \um wide, 2 large cells (50 \um wide or more) wide dorsally and 2 cells wide ventrally; ventral surface of costa convex, bearing hairs averaging 170--230 \um in length, incurved or hamate. Wings 12--20 cells wide, naked dorsally, but with some setae occurring ventrally; hairs of lamina margins mostly paired, incurved or hamate, up 170--230 \um. Lamina cells ca. 40--65 x 30--45 \um, often subisodiametric. Gemmae produced  occasionally along thallus margins on some distance from the apex, ca. 135--225 x 400--650 \um at the time of abscission. Sexual condition dioicous, mostly sterile. Androecial branches naked, each with 4-8 antheridia in two rows. Gynoecial branches rotund-ovate, with no costa, with long mostly solitary, straight hairs on the margins and sometimes a few on the dorsal surface. Sporophyte not seen.

 

Varieties 2 (2 in the flora): North America, Central America, South America, Eurasia, Africa, Australia, Oceania.

 

1. Thallus margins strongly recurved; costa uniformly 2 cells wide ventrally; thallus margins with hairs almost uniformly paired, hairs thin-walled, long, strongly falcate; gemmae occasional … 4a. Metzgeria leptoneura var. leptoneura

1. Thallus margins faintly to weakly recurved; costa 2-- 4 cells wide ventrally; thallus margins with hairs not strongly falcate, solitary, paired, or 3--4(--6) arising from one point; gemmae unknown … 4b. Metzgeria leptoneura var. polychaeta

 

4a. Metzgeria leptoneura var. leptoneura

 

Thalli strongly recurved along margin, wings mostly 14--20 cells wide. Costa 2 cells wide ventrally. Thallus marginal hairs in pairs.  Gemmae occasional.

 

Wet, deeply shaded, highly protected ledges, rock crevices, cliffs near waterfalls, rarely (in our area) on the tree trunks; 0--1300m; B.C.; Alaska, Ga., N.C., Tenn., Va., W.Va.; Central America, South America, Eurasia, Africa, Australia, Oceania.

 

4b. Metzgeria leptoneura var. polychaeta R.M.Schuster, Phytotaxa, 202(1): 70. 2015  E

 

Thalli faintly to weakly recurved along margin. Costa 2--4 cells wide ventrally. Thallus marginal hairs solitary or groups of 2--4(--6) arising from one point, wings mostly 8--14 cells wide. Gemmae not known.

 

Ecology poorly known, “on cliff wall along stream”; moderate elevation; Tenn. Endemic.

 

5. Metzgeria lindbergii Schiffner, Denkschr. Kaiserl. Akad. Wiss., Math.-Naturwiss. Kl., 67: 182. 1898

Metzgeria conjugata var. japonica S. Hattori, J. Hattori Bot. Lab., 15: 80. 1955

 

Plants pale yellow-green to pure green, scarcely shiny to dull. Thalli 10--30 x 0.6--1.0 mm, moderately convex dorsally, margins distinctly but not strongly incurved; branching dichotomous, ventral branches uncommon. Costa 100--150 \um wide, 2 large cells (45--50 \um) wide dorsally and 3--4 cells wide ventrally; ventral surface of costa convex, bearing hairs. Wings 10--20 cells wide, naked dorsally, but with some hairs ventrally; hairs in lamina margins straight, mostly paired, but in weakly developed individuals often solitarily with only scattered hairs paired. Lamina cells ca. 30--45 x 28--38 \um, often subisodiametric. Gemmae unknown. Sexual condition autoicous, commonly fertile. Male and female branches usually close together on the same thallus. Androecial branches transversely subglobose, naked. Gynoecial branches obcordate, notched at apex, ventral face hairy. Capsule with inner cells ca. 36--42 x 17--20 \um, with semiannular thickenings. Elaters unispiral, flexuous, ca. 7 \um wide in middle part, reddish brown. Spores yellowish brown 16--21 \um.

 

Bark, cliffs, rocks in different types of forests and in open sites excluding Arctic; 0--300 m; B.C.; Alaska, Ark., Calif., Md.; East Asia.

 

6. Metzgeria myriopoda Lindberg Acta Soc. Fauna Fl. Fenn. 1(2): 9. 22. 1877  E

 

Plants grass-green to yellow green, loosely prostrate, ultimate segments somewhat ascending (and sometimes becoming narrow). Thalli ca. 5--25 x 0.3--0.85(--1.2) mm, distinctly convex with recurved margins; branching pseudichotomous, commonly or  rarely with ventral branches. Costa 100--160 \um wide, 2--3 cells wide dorsally (cells ca. 35--42 x15--20 \um) and (2--)3--6 cells wide ventrally, the ventral cortical cells not or little larger than medullary cells, in 4--5 strata, thick-walled; ventral surface of costa convex, bearing numerous stiff, usually stout hairs averaging 60--75(--95) \um in length. Wings (5--)12--14(--22) cells wide, naked dorsally, but with isolated hairs occurring ventrally; hairs of thallus margins mostly solitary, but sometimes in pairs or even 3 or 4 arising from one point, hairs straight, stiff and short, up 50--95 \um in length. Lamina cells ca. 30--40(--55) x 25--35 \um, often subisodiametric. Gemmae freely produced, not crowded, along thallus margins at some distance from apex, their margins without setae, or with low, rudimentary setae. Sexual condition dioicous. Androecial branches not seen. Gynoecial branches densely hairy with short, paired hairs on margins. Sporophyte unknown.

 

Vertical sides of shaded and damp rocks as well as bark of trees; 0--300m; Ala., Ark., D.C., Fla., Ga., Miss., N.C., S.C., Tenn., Tex.

 

Metzgeria myriopoda fo. pseudotemperata R.M. Schuster, J. Hattori Bot. Lab., 70: 150. 1991, is an illegetimate name in the synonymy of M. myriopoda.

 

 

7. Metzgeria setigera R.M.Schuster ex Crandall-Stotler & L.Söderström, Phytotaxa 202(1): 69. 2015  e

 

Plants yellow green, loosely prostrate, ultimate segments somewhat ascending. Thalli ca. 5--25 x 0.3--0.85 mm (rarely up 1.2 mm wide), plane with loosely recurved margins, branching sporadically dichotomous, lateroventral branches common. Costa 100--130 \um wide, 2--3 cells wide dorsally (cells ca. 35--42 \um x15--20 \um) and 3--5 cells wide ventrally; ventral surface of costa convex, commonly bearing hairs averaging 80--130 \um in length. Wings 5--20 cells wide, naked or sporadically hairy dorsally, hairy ventrally; hairs on lamina margins mostly solitary, sometimes very sparse in shade forms, hairs straight, stiff and short, up 90--200(--300) \um in length. Lamina cells ca. 42--55 x 32--45 \um, often subisodiametric. Gemmae sporadically present, along thallus margins at some distance from apex. Sexual condition dioicous. Androecia unknown. Gynoecial branches adaxially concave, cordate, short (up to 140--150 \um long), densely hairy with hairs ca. 125--150 \um, straight to arched. Capsule, elaters, spores unknown.

 

Ecology poorly known “occur chiefly on damp, shaded rocks (Schuster, 1992: 689)”; moderate elevations; N.C., S.C. Endemic.

 

8. Metzgeria temperata Kuwahara, J. Hattori Bot. Lab., 40: 219. 1976

 

Plants pale to bright yellow-green, prostrate after long drying becoming pale yellowish to whitish green, not bluish, ultimate segments somewhat ascending, with tapered, semi-erect gemmiparous branches.. Thalli plane to slightly convex with recurved margins, ca. 10--25 x 1.--1.5 mm (mature non-gemmiparous shoots), furcately branched. Costa 100--130 \um wide, 2(--3) cells wide dorsally and 2(--3) cells wide ventrally; ventral surface of costa convex, commonly bearing hairs averaging 80--130 \um in length. Wings 7--28 cells wide, naked dorsally, but with scattered hairs ventrally; hairs of margins mostly solitary, rarely paired, straight. Lamina cells ca, 28--54 x 26--46 \um, often subisodiametric. Gemmae freely produced on specialized tapered shoot tips, not crowded, along thallus margins some distance from apex or (rarely) on ventral surface of costa. Sexual condition dioicous. Male plants scarcely smaller then female ones. Androecial branches vittate, bean-shaped, normally naked. Gynoecial branches obcordate, hairy on margins. Capsule with both inner and outer cells with nodular thickenings in vertical sides. Elaters 250-400 x 8 \um. Spores 18--21 \um.

 

Mostly on bark of conifers, rarely on broadleaved trees or partly shaded rocks; 0--2100m; B.C.; Alaska, N.C., Oreg., Tenn., Va., Wash.; East Asia.

 

9. Metzgeria uncigera A. Evans Ann. Bot. 24: 276. 1910

 

Plants pale yellowish green, prostrate to ascending. Thalli plane to slightly convex with loosely recurved margins, linear, elongate, ca. 10--25 x 0.6--1.2 mm, furcately branched, sometimes also with ventral branches. Costa 60--80 \um wide, 2 cells wide dorsally and 2(--3) cells wide ventrally; dorsal cells ca. 27--35 \um width, ventral side of costa frequently hairy. Wings 14--20 cells wide, dorsal surface naked, ventral surface occasionally with scattered hairs; hairs of lamina margins solitary, short (50--80 \um in length), usually straight, but occasionally (especially in young thalli) hooked at the tips. Lamina cells ca. 25--35 x 20--30 \um, often subisodiametric. Gemmae freely produced  not crowded, along thallus margins some distance from apex or (rarely) on ventral surface of costa. Sexual condition dioicous. Androecial branches unknown. Gynoecial branches orbicular-ovate to obcordate, densely hirsute both on margins and outer face. Sporophyte unknown.

 

Bark of trees mostly in humid subtropical communities; low to moderate elevations; Ala., Fla., Ga., Miss., N.C., S.C.; Central America.