BFNA Title: Mylia
Jungermanniaceae - Mylia
XXX. MYLIA Gray, Nat. Arr. Brit. Pl. 1:693, 1821, as Mylius · [named for Willem Mylius, a Dutch physician]
Marie L. Hicks
Plants simple or sparingly branched, prostrate or decumbent with ascending apices when crowded, forming loose mats or thick tufts, green to reddish brown. Stems rather fleshy, 450‑‑600 µm in diameter; branching mostly terminal or lateral and axillary; cortical and medullary cells not distinctly differentiated; rhizoids scattered over ventral stem surface, long, often dense, especially at leaf and underleaf bases. Leaves succubous‑oblique, alternate, circular to ovate in outline; leaf cells irregularly hexagonal, large, ca. 45‑‑55 µm in diameter, with large, bulging trigones and thin intervening walls; oil bodies granular‑botryoidal, opaque, or hyaline. Underleaves present, lanceolate. Specialized asexual propagation by gemmae on leaf margins, ovate to elliptical, 1‑‑2-celled. Sexual condition dioecious. Androecia intercalary; bracts imbricate, similar to leaves, with saccate base; antheridia 1‑‑3 per bract with large jacket cells; stalk 1‑seriate, long. Gynoecia terminal on main shoot; bracts sub‑orbicular, entire, larger than leaves, partially enclosing the perianth; bracteole present, lanceolate; perianth exerted about 1/4‑‑1/2 above bracts, inflated, laterally compressed, the mouth wide, truncate, entire to ciliate; perigynium not present. Seta ca. 9‑‑11 cells in diameter. Capsule short ovoid, 4‑valved; walls 3‑‑5 cells thick, exterior layer with thickenings that extend inward, the interior layers with semiannular thickenings; elaters 120‑‑160 ´ 8‑‑10 µm, 2‑spiral. Spores 15‑‑20 µm.
Species 4 (2 in the flora): North America, Europe and Asia.
SELECTED REFERENCES Schuster, R.M. 1969. The Hepaticae and Anthocerotae of North America. New York.
1. Distal leaves on gemmiparous shoots longer than wide, with subacute apices; gemmae green; cuticle smooth . . . . 1. Mylia anomala
1. Distal leaves on gemmiparous shoots wider than long, with rounded apices; gemmae brownish; cuticle rough, fissured . . . . 2. Mylia taylori
1. Mylia anomala (Hooker) Gray, Nat. Arr. Brit. Pl. 1: 693. 1821
Jungermannia anomala Hooker, Brit. Jungerm. pl. 34. 1813
Plants with shoots 20‑‑30 ´ 2.4‑‑3 mm, prostrate, forming mats over peat or occurring as stems intermingled with moss, pure green to yellowish or reddish brown. Stems ca. 10‑‑12 cells in diameter, branches few, most arising beneath perianths; cortical cells 28‑‑35 µm in diameter, slightly smaller than medullary (32‑‑42 µm); interior cells with small trigones. Leaves contiguous to imbricate, spreading to erect, orbicular to ovate, ca. 1400 ´ 1450 µm, narrowed at the insertion, concave; leaves on gemmiparous shoots progressively narrower toward stem apex, becoming lanceolate (ca. 1400‑‑1500 ´ 1100‑‑1150 µm) with subacute apex; median leaf cells large, 50‑‑60 ´ 45‑‑50 µm, basal cells larger, 50‑‑55 ´ 65‑‑75 µm; cuticle smooth; trigones large, bulging, knotlike; oil bodies 6‑‑18 per cell, ovoid, 7‑‑8 ´ 5‑‑7 µm, granular‑botryoidal with protruding globules, hyaline. Underleaves distinct, lanceolate, large (to 500‑‑600 µm), often hidden among rhizoids. Specialized asexual propagation by gemmae, often present on distal lanceolate leaf margins, spherical to elliptical, 30‑‑40 ´ 45‑‑50 µm, 2‑celled, green. Androecia intercalary; bracts 4‑‑7 pairs, entire, ovate with saccate base, antheridia 1‑‑2 per bract. Gynoecia terminal on main shoot; bracts similar to leaves, larger, somewhat recurved; bracteole large, lanceolate; perianth inflated, compressed laterally, exerted above bracts about 1/2 its length; mouth 2-labiate, entire to slightly crenulate.
Peat bogs or on moist peaty soil over outcrops, Arctic‑alpine; s, sw and w Greenland; Alta, B.C., Nfld., N.W.T., N.S., Ont., Que., Yukon; Alaska, Conn., Maine, Mich., Minn., N.H., N.J., N.Y., Pa., Wash., W.Va., Wis.; n Europe; e Asia.
Commonly found in northern Sphagnum bogs, this species occurs as far south as the Cranberry Glades of West Virginia.
2. Mylia taylori (Hooker) Gray, Nat. Arr. Brit. Pl. 1:693. 1821
Jungermannia taylori Hooker, Brit. Jung. pl. 57. 1813
Plants large, with shoots 30‑‑80 ´ 3‑‑3.6 mm, decumbent to ascending when crowded, forming thick mats or tufts, green to reddish or purplish brown. Stems 480‑‑550 µm in diameter, simple or sparingly branched with terminal branches; cortical cells 28‑‑40, thin‑walled, medullary cells 32‑‑40 with small trigones. Leaves succubous‑oblique, spreading, imbricate, orbicular to broadly ovate, 1.5‑‑2 ´ 1.8‑‑2.4 mm, slightly concave at the base, convex distally or with deflexed margins; leaf cells large, median cells 45‑‑60 ´ 40‑‑45 µm, smaller along margins, ca. 35‑‑45 µm; cuticle rough, finely fissured forming plates; trigones large and bulging, knotlike; oil bodies 7‑‑12 per cell, ellipsoidal, large, 15‑‑18 ´ 8‑‑10 µm, coarsely granular, opaque, brownish‑gray, partially obscuring the cell lumen. Underleaves distinct, subulate to lanceolate, up to 0.5 mm, hidden among rhizoids. Specialized asexual propagation frequent, by gemmae on margins of broadly ovate distal leaves, elliptical to ovate, 25‑‑30 ´ 40‑‑45 µm, 1‑‑2 celled, brownish. Androecia intercalary; bracts 4‑‑8 pairs, imbricate, similar to leaves with saccate base; antheridia 2‑‑3 per bract. Gynoecia terminal on main stem, often with 1‑‑2 subfloral innovations; bracts entire, similar to and slightly larger than leaves, ca. 2 ´ 2.2 mm; bracteole lanceolate, large, to 0.7 mm; perianth partially hidden by bracts, exerted ca. 1/2 its length, laterally compressed, the mouth contracted, ciliate, the cilia 4‑‑6 cells long.
Moist mountains on humus over outcrops and in rocky crevices with at least a small accumulation of peat; s Greenland; B.C., Nfld., N.S.; Alaska, Maine, N.H., N.Y., N.C., Tenn., Wash.; Europe; eAsia.