Plagiochila macrostachya Lindenb.

Gradstein, S. Robbert & Reeb, Catherine, 2022, The genus Plagiochila (Dumort.) Dumort. (Marchantiophyta) in Madagascar, Cryptogamie, Bryologie 20 (5), pp. 65-106 : 82-86

Plagiochila macrostachya Lindenb.

( Fig. 11 )

Plagiochila macrostachya Lindenb. , Species Hepathicarum (fasc. 2-4): 75 (1840). — Type: Jamaica. Hb. Hooker (lecto-, designated by Heinrichs [2002], W-Lindenb. 66).

A D B F C G H E

A D E B C H F I G

Plagiochila granditexta Steph. , Bulletin de l’Herbier Boissier (sér. 2) 4 (2): 165 (1904) syn. nov. — Type: Madagascar. Unknown locality, Hildebrandt s.n. (holo-, G00045478!).

DISTRIBUTION AND HABITAT. — Peri-Afro-American: common throughout the mountains of tropical America ( Heinrichs 2002), very rare in Madagascar; new to Africa. Previously recorded from La Réunion but the record belongs to P. boryana according to Grolle (1995).

DESCRIPTION (see also Vanden Berghen 1981 as P. granditexta ; Heinrichs 2002) Plants robust, c. 5 mm wide, vegetative branches scarce, all branches intercalary, rhizome-like creeping shoot present. Mature stem leaves loosely imbricate, widely spreading, subopposite, ovate-oblong to ovate-triangular, c. 1.5-2× longer than wide, widest at the base, ventral base with a high shoulder and ampliate on stem leaves, apex rounded, margins unbirdered, with (5-)10-18 coarse triangular teeth along the apical and ventral margin, the teeth (3-)4-8 cells long, 3-6 cells wide at the base, sometimes broken; dorsal and ventral bases rather shortly and narrowly decurrent, the opposite bases almost connate. Leaf cells somewhat elongate, large, 35-40 µm wide in midleaf, trigones medium-sized, triangular-radiate with concave sides, vitta-like area absent; cuticle smooth; oil bodies not observed. Underleaves absent. Male plants not seen. Female bracts larger and more coarsely toothed than vegetative leaves. Perianth (juvenile) without stalk, perianth mouth with numerous triangular teeth. Vegetative reproduction not observed.

NOTES

Plagiochila macrostachya (sect. Hylacoetis) is recognized by the robust plants (at least 5 mm wide) with intercalary branching, subopposite leaves with a shoulder and distinctly ampliate in basal stem leaves, triangular teeth, large leaf cells (35-40 µm wide in midleaf) and a smooth cuticle. The species resembles P. boryana in the large leaf cells but in the latter species the leaves are alternate, the teeth linear and the cuticle papillose. The plants from Madagascar were described by Stephani as P. granditexta Steph. , which is identical to P. macrostachya in all respects. Vanden Berghen (1981) erroneously illustrated the leaves of P. granditexta as being alternate.

Figures

FIG. 11. ― Plagiochila macrostachya Lindenb.: A, habit; B, C, shoot in ventral view, showing ampliate leaf bases; D, shoot in dorsal view; E, leaves; F, upper portion of leaf; G, intercalary branching; H, I, midleaf cells. From Bolivia, Churchill 23663 (GOET).Scale bars: A, 5 mm; B, C, E, 1 mm; D, G, 0.5 mm; F, 0.25 mm; H, I, 0.05 mm.