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BFNA Title: Leueuneaceae |
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WORK IN PROGRESS: 29. LEJEUNEACEAE Casares-Gil Barbara M. Thiers Jungermanniaceae Reichenbach tribe Lejeuneae Frye & L. Clark (as Lejeuneoideae) Plants differentiated dorsiventrally; prostrate, or with some ascending or pendent branches; branches always at lateral leaf bases, sometimes replacing basal part of leaf (Frullania-type or Lejeunea-type). Lateral leaves incubous, unequally 2-lobed, larger lobe dorsal, smaller lobe (lobule) ventral, folded against dorsal lobe and fused to stem; oil bodies present; asexual reproduction by deciduous leaves or branches, or discoid, multicellular gemmae. Underleaves present or absent, 2-lobed or entire. Rhizoids at underleaf bases. Androecial bracts each containing 1--2 spheric, colorless antheridia, stalk 1-seriate. Gynoecia with 1(--2) bract cycles surrounding 1 archegonium; innovational branches 0--2; perianths usually with 3--5 longitudinal keels, distinctly beaked. Sporophyte foot discoid, small; seta to ca 3 mm, articulate, outer cell rows 12 or 16, inner cell rows 4; capsule barely exserted, spheric, 4-valved, wall 2-layered; elaters all fixed, weakly 1--2 spiraled, trumpet-shaped, attached near valve apex; spores green, multicellular, surface granulose with scattered rosettes of triangular tubercles. Genera ca. 75, species ca. 1000 (17 genera and 62 species in the flora): primarily tropical and subtropical regions. The family Lejeuneaceae is the largest family of Jungermanniales. R. M. Schuster (1963, 1984) recognized seven subfamilies of Lejeuneaceae, the three largest of which, Cololejeuneoideae, Lejeuneoideae, and Ptychanthoideae, occur in North America. Lejeuneaceae are similar to Jubulaceae in the presence of both Frullania- and Lejeunea-type vegetative branches, a small sporophyte foot, and trumpet-shaped elaters that are always attached to the capsule valves. The position of the hyaline papilla (the mucilage hair found at or near the apex of the ventral lobe) is important in determining relationships within the family, especially in subf. Lejeuneoideae. SELECTED REFERENCES Evans, A. W. 1902. The Lejeuneae of the United States and Canada. Mem. Torrey Bot. Club 8: 113--183. Schuster, R. M. 1980. Lejeuneaceae. In: R. M. Schuster. 1966--1993. Hepaticae and Anthocerotae of North America. New York. Vol. 4, pp. 706--1314. 29b. LEJEUNEACEAE Casares-Gil subf. LEJEUNEOIDEAE Plants 0.25--1.5 mm wide, prostrate or pendent; vegetative branches collared basally, subtending entire lateral leaves (Lejeunea-type branches). Stems: epidermal cells 7--9, medullary cells 3--30, cells of medulla usually smaller, thicker-walled than those of epidermis; ventral merophyte 2 cells wide (4 in Leucolejeunea). Leaves: insertion line J-shaped (lobe and lobule broadly connate with stem); cell walls hyaline (brown in Ceratolejeunea); ocelli sometimes present. Lobules: free margin with 1(--2) teeth, a tear-shaped, thin-walled cell (hyaline papilla) on margin at tooth base. Underleaves 2-lobed (entire in Leucolejeunea). Androecia with bracteoles at base only. Gynoecia on long or short branches, usually subtended by 1--2 collarless innovations. Sporophyte seta of 12 outer cells surrounding 4 inner cells; capsule walls almost colorless, inner wall lacking fenestrate thickenings; elaters usually colorless, 3--9 per valve, spiral thickenings vestigial. Genera 38, species ca. 600 (8 genera and 44 species in the flora). Lejeuneaceae subf. Lejeuneoideae has been called Jungermanniaceae Reichenbach subf. Lejeuneae Frye & L. Clark subtribe Tomiae Frye & L. Clark or Lejeuneaceae Casares-Gil subf. Schizostipae (Spruce) R. M. Schuster, but the latter names are illegitimate (not based on names of included genera). |
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