Lejeunea apiculata

Detailed description

Plants light, opaque green, tightly adnate to substrate, leafy shoots up to 675-725 µm broad, freely, irregularly ramified, the leading axes usually gynoecial, the branches commonly soon androecial otherwise usually gynoecial; innovations beneath unfertilised or fertilised gynoecia always developed, at least normally Lejeunea-type. Stem slender c.50 µm diameter; cortical cells in 7 rows, somewhat but not greatly firm-walled, surrounding c.4 medullary cell rows of somewhat inferior size. Leaves contiguous to weakly imbricate, ovate-lanceolate, c.250-275 x 500-550 µm, at most feebly convex, the short-acuminate apices often a little deflexed, entire-margined, smooth (marginal cells not or hardly projecting as crenulations), the acuminate apices ending in mostly 3-4 superposed single cells which are subisodiametric or weakly elongated (1: 1-8). Lobules ovoid, strongly inflated except in and near apical tooth, about 0.3 length of lobe, with a blunt 1-celled apical tooth, the fine hyaline papilla at antical base. Underleaves small, c.115-135 x 135-175 µm long. c.0.6-0.7 bifid via a U-shaped sinus, divided to within 2-3 cells of rhizoid-initial region; lobes narrow, often their acuminate apices arched toward each other, 3-4 cells broad at base and long-tapered into a uniseriate apex formed of mostly 2 superposed cells. Rhizoid-initial region prominent, mostly formed of c.12-16 cells giving rise to conspicuous rhizoid-initial discs, the plants closely adherent. Cells in 2-3 marginal rows rather firm-walled and with obscure trigones and weak, isolated intermediate thickenings; laminar cells becoming clearly larger, 23-26 x 24-28 µm, 5-6-angled, weakly or hardly firm-walled but with rather large, ± convex-sided but not nodular trigones, + isolated, scattered intermediate thickenings. Oil bodies in 1-2 marginal rows lacking, in third row vestigial or small; laminar cells with mostly 4-8 variable usually fusiform oil-bodies varying from transversely few-septate to botryoidal to granular-botryoidal, the larger 4.5-5.5 x 15.0-17.5 µm. Autoecious. Androecia forming short lateral branches lacking sterile leaves, mostly spicate, compactly so, with c.4-8 or more closely imbricate, inflated pairs of bracts, their arched keels ± inflated cells; bracts diandrous; bracteoles 1-2 at androecium base. Gynoecia on short to lateral branches (gynoecia at apices of leading shoots rare; apical dominant normal); always innovating, innovations single, usually remaining sterile but ± elongating; at times innovations producing 1-2 male and/or female branches. Female bracts in 1 pair, sheathing basal 0.45-0.55 or perianth; bracts with lobes ovate to obovate-lanceolate, acute to longly acute at apex, edentate or with 1-4 variable, obtuse to obscure teeth; lobule lanceolate to narrowly obovate, acute to apiculate, often with a tooth of inner margin, the distal third or more free, the keel short to long, unwinged. Bracteole free, variably obovate to ovate, 0.4-0.6 bifid, sinus V- to narrowly U-shaped, lobes erect and acute, often with 1(-2) teeth of one or both margins. Perianth obovate, a little complanate, the lateral keels more pronounced, the ventral shorter, often weak and abbreviated; perianth keels smooth; perianth apex truncate, the long beak sometimes a little recessed.