Marchesinia

  • Authority

    Gradstein, S. Robbert. 1994. Lejeuneaceae: Ptychantheae, Brachiolejeuneae. Fl. Neotrop. Monogr. 62: 216. (Published by NYBG Press)

  • Family

    Lejeuneaceae

  • Scientific Name

    Marchesinia

  • Type

    Type. Jungermannia mackaii Hooker (= Marchesinia mackaii (Hooker) S. Gray). Genus named after J. G. Marchesini, Italian Professor of medicine and one of the sponsors of Micheli s Genera Plantarum.

  • Synonyms

    Phragmicoma, Homalolejeunea, Jungermannia mackaii Hook., Marchesinia mackaii Gray

  • Description

    Genus Description - Plants 2-10 cm long × (l-)2-4 mm wide, dull or glossy green to brown to black, ascending or pendent when fertile, largely growing free from the substrate and often forming mats, irregularly pinnate, female shoots forked by paired, repeatedly fertile innovations. Branching predominantly Lejeunea-type, occasionally Frullania-type, flagelliform branches lacking. Stems rigid, brown, in cross section with weakly enlarged epidermis, epidermal cells quadrate-rectangular, dorsal epidermal cells wider and somewhat higher than the medullary cells, ventral epidermal cells not larger than medullary cells, all cell walls thickened, epidermal walls brown, medulla colorless; ventral merophyte (4-)6-ll cell rows wide. Leaves plane or deflexed when dry, obliquely to widely spreading when moist, apex rounded to acuminate, rarely obtuse, plane or reflexed, margins entire or toothed; leaf cells isodiametric-hexagonal to slightly elongate, averaging 30 µm in diam., walls sometimes with darkish pigmentation, trigones usually triradiate, sometimes very small, intermediate thickenings usually frequent, one per wall, oil bodies homogeneous in neotropical species, ocelli and vitta lacking (the type species of the genus, Marchesinia mackayi from Europe, has segmented oil bodies; see Geissler, 1990). Lobules l/6-l/3× lobe length, sometimes reduced, flat or slightly inflated, with 1-4 teeth; hyaline papilla positioned below the proximal base of the apical tooth on the inner surface of the lobule. Underleaves 3-8× stem width, apex rounded, margins entire or toothed, bases usually decurrent, insertion line deeply arched in neotropical species; underleaf base at the rhizoid disc bistratose, in cross section with up to eight (or more?) rhizoid disc initial cells. Androecia on elongated branches, terminal or intercalary, bracts smaller than leaves, becoming progressively smaller towards apex of spike, lobules large, hypostatic, bracteoles present throughout spike, smaller than underleaves; antheridia 2 per bract. Gynoecia with (1-)2 pycnolejeuneoid subfloral innovations, bracts in one series, suberect, about as large as leaves but narrower, often toothed, lobules reduced or well-developed, keel unwinged; bracteoles as long as bracts, undivided or bifid, often toothed. Perianths usually exserted and becoming brown when mature, obovate-oblong, strongly flattened with plane ventral and dorsal surface, the lateral margins entire, the apex broadly truncate and distinctly beaked, cell walls thin-walled below, thickened towards apex. Sporophyte: seta not articulate, made up of (16-) 25 outer cell rows surrounding (4-)20 inner cell rows; elaters 72 per capsule (van Slageren, 1985), with two pale brown spirals; otherwise as in the tribe. Vegetative reproduction by caducous or fragmenting leaves in Marchesinia brachiata. Chemistry: eugenol-derivates, luteolin di-C-glycosides.

  • Discussion

    In the neotropics Marchesinia may be recognized when sterile by its rigid, brown stems with irregular, Lejeunea-type branching, elongated leaves with isodiametric cells and radiate trigones, small, rather flat lobules with several teeth and large, strongly decurrent underleaves with deeply arched insertion line. The depth of the insertion almost equals the length of the underleaf (measured from the rhizoid disc to the apex).

    The genus is most closely related to Lopholejeunea. The two genera share the occurrence of blackish pigmentation in cell walls; morphological differences include the different stem structure, the different gynoecium, etc. Chemically, the two genera are also quite different: eugenol-derivates are the chemical markers of Marchesinia whereas calamenanes characterize Lopholejeunea.

    Sterile Marchesinia closely resembles Symbiezidium (Brachiolejeuneae), but the latter has strongly inflated, never reduced lobules with involuted free margin and without or with an obscure tooth; in Marchesinia lobules are rather flat and the free margin is usually plane (incurved in very small lobules) and has (l-)2-4 evenly spatiated teeth. When fertile, Marchesinia is immediately recognized by its flat, smooth perianth positioned on an elongated shoot and with (l-)2, usually fertile innovations; male spikes have bracts with large, hypostatic lobules and bracteoles throughout the spike. In neotropical Symbiezidium the perianth is somewhat inflated, ciliate-laciniate and positioned on a very short lateral branch, with one short, sterile innovation; the male spike has one or two bracteoles limited the base of the spike only. A flat perianth with two innovations is also found in the Andean genus Lindigianthus, but the latter has broadly recurved leaves (± plane in Marchesinia), fragile stems made up of thin-walled cells (thick-walled in Marchesinia) and epistatic male bracts. Habitually Lindigianthus is easily recognized in the field and in the herbarium by its glossy brown color.

    Within Ptychanthoideae, Marchesinia is one of the few genera with a rather thick seta consisting of more than 20 longitudinal rows of cells. In material of M. brachiata from the Galapagos Islands (vanderWerff l439, U) we found a seta of about 40-45 longitudinal cell rows: ca. 25 outer cells and 16-20 inner cells. A thick seta was also recorded by van Slageren and Berendsen (1985).

  • Distribution

    The genus Marchesinia occurs in tropical America, tropical Africa and western Europe and contains five species, two of which occur in tropical America. The genus occurs throughout the humid portions of tropical America, from the lowlands to high montane elevations up to 3300 m. The species grow on bark and rock in primary and secondary rain forests, in scrub and in plantations.

    Africa| Europe|