BFNA Title: Gymnocolea
2. GYMNOCOLEA (Dumortier) Dumortier, Rec. d'Obs. 17. 1835 * [Greek, gymno‑, naked and koleo‑, female sheath, in reference to the large perianth, not concealed by bracts]
Marie L. Hicks
Jungermannia sect. Gymnocolea Dumortier, Syll. Junger. Eur. 52. 1831
Plants creeping with ascending apices, mat forming or erect when crowded, green to blackish‑brown or scorched in insolated sites. Stems 7‑‑8 cells in diameter, branching terminal, lateral or ventral intercalary, from older stems, cortical cells thin‑walled, 20‑‑25 \um, little differentiated from medullary; rhizoids very sparce, scattered along ventral stem, colorless. Leaves succubous‑oblique, bilobed, the lobes obtuse to rounded, occasionally acute, often concave; leaf cells subisodiametric, small, 22‑‑30 \um; cuticle smooth, occasionally slightly verruculose; walls without distinct trigones; oil bodies smooth to slightly granulate. Underleaves absent or occasional and small, of 1‑‑3 cells from narrow ventral merophytes of 2‑‑4 cells. Specialized asexual propagation by detached inflated perianths that float on water; gemmae absent or very rare, angular, brown, 1‑‑2 celled. Sexual condition dioicious. Androecia terminal, spicate, becoming intercalary, of ventricose bracts similar to leaves but smaller; antheridia one per bract; stalk 1‑seriate. Gynoecia terminal on main stem or branch, often with subfloral innovations; bracts similar to leaves; bracteole absent; perianth exerted, inflated, smooth, the mouth contracted; perigynium absent. Sporophyte seta cross section of 8 exterior cells and 4 interior cells; capsule ovoid, brown, valves 2 cells thick, the walls with nodular thickenings; elaters 120‑‑200 × 6‑‑9 \um, 2‑spiral, brown; spores 10‑‑18 µm, finely papillate, brown.
Species 6 (2 in the flora); cool parts of the Northern Hemisphere and South America.
SELECTED REFERENCES Schuster, R. M. 1969. The Hepaticae and Anthocerotae of North America, Vol. II. New York.
1. Leaf lobes with obtuse or rounded apices; gemmae absent; perianths inflated, easily detached . . . 1.Gymnocolea inflata
1. Leaf lobes with acute apices; gemmae rare; perianths uncommon, not easily detached . . . 2. Gymnocolea acutiloba
1. Gymnocolea inflata (Hudson) Dumortier, Rec. d'Obs. 17. 1835
Jungermannia inflata Hudson, Fl. Angl. ed. 2. 2: 511. 1778
Plants with shoots 5‑‑25 × 0.75‑‑1.2 mm, scattered among mosses or in crowded mats, green in shade or brownish‑black in exposed sites. Stems slender, 130‑‑300 \um, branching irregular, terminal or ventral intercalary. Leaves distant to scarcely imbricate, spreading, flat or more often concave, as long as wide or slightly longer, 400‑‑900 × 350‑‑800 µm, 2-lobed 1/4‑‑1/3, the sinus narrow, the lobes obtuse to rounded, entire; median leaf cells 22‑‑27 x 25‑‑30 \um, marginal cells 20‑‑24 \um; cuticle smooth, walls evenly thickened; trigones absent; oil bodies 4‑‑8 per cell, ovoid or spherical, 3‑‑4 × 5‑‑6 \um, finely granulate. Underleaves absent. Specialized asexual propagation by detached, unfertilized, inflated perianths that float on water; gemmae absent. Androecial bracts up to 8 pairs, contiguous, concave, 2-lobed. Gynoecia commonly with subfloral innovations; bracts similar to leaves in shape, slightly larger; perianths often present, exerted well above bracts, globose to oblong, inflated, large compared to the size of the shoot; mouth contracted, dentate‑lobulate; easily detached from stem.
Igneous rock outcrops subject to at least periodic seepage, often in direct sunlight; also around rock pools and in bogs; e, w, nw Greenland; Miquelon; Alta., Ark., B.C., Man., Nfld., N.S., Nun., Ont., Que., Yukon; Alaska, Calif., Colo., Conn., Maine, Mass., Mich., Minn., N. C., N.H., N.J., N.Y., Oreg., Pa., S.Dak., Tenn., Vt., Wash., Wyo.; Europe; Asia (Japan).
The variety Gymnocolea inflata var. heterostipa (Carrington & Spruce) K. Müller, a dubious taxon with frequent small intercalary branches and small underleaves, has been recognized from plants collected in East Greenland and Minnesota. This plant is doubtfully distinct and its gametophytic differences may be an environmentally induced variation. In Europe, where the variety was first recognized, no distinct limits have been found between this variety and the typical form of Gymnocolea inflata.
2. Gymnocolea acutiloba (Schiffner) K. Müller, Rabenh. Krypto. Fl. 6: 745. 1910
Lophozia acutiloba Schiffner, Hedwigia 48: 187. 1909
Plants with shoots 10‑‑15 × 0.6‑‑0.9 mm, forming mats, green to brown or blackish. Stems 100‑‑180 µm, sparingly branched, the branches terminal, occasionally intercalary. Leaves remote to slightly overlapping, nearly flat, ovate‑quadrate, slightly longer than wide, 370‑‑600 x 320‑‑500 \um, 2-lobed 1/3‑‑1/2 , with a narrow sinus and subacute to acute lobes ending in 1‑‑2 single cells; lateral leaf margins often with a small tooth; leaf cells subquadrate, 22‑‑28 \um, walls slightly thickened, often brownish; trigones not developed; oil bodies 3‑‑8 per cell, ovoid or spherical 4‑‑6 x 5‑‑8 \um, smooth or slightly granular. Underleaves absent or vestigial, of small cilia or slime papillae. Specialized asexual propagation usually absent or rarely by gemmae on margins of leaf lobes, angular, 14‑‑18 µm, 2‑celled, brown. Plants usually sterile. Gynoecia with bracts similar to leaves in shape, larger; perianth rarely produced, not easily detached, inflated, clavate, the mouth dentate.
Igneous rock that are perhaps copper‑bearing, where they may occur with other rare species such as Cephaloziella massalongoi or Gymnomitrion concinnatum; w Greenland; Alaska, Maine, Tenn.; Europe.