Monachosoraceae

Abstract

Terrestrial ferns of rather small to large size with short-creeping or ascending, dictyostelic stem. Petioles close, non-articulate, well-developed, in certain species some without lamina, consisting only of a short, very thick, finger-like trophopod. Stem without scales or larger trichomes, bearing only minute, few-celled, cylindrical, glandular hairs, these also occurring on the foliar parts. Lamina once pinnate to quadripinnate + pinnatifid, herbaceous; primary divisions catadromous (Monachosorum subdigitatum) or anadromous (M. flagellare, M. maximowiczii). Petiole with two strap-shaped vascular bundles with hippocampiform xylem, these merging upward into one gutter-shaped bundle; adaxial side with a single groove with slightly raised centre, this continuous with the grooves on the secondary rachises (if present). Leaf axes bearing, beside the minute glandular hairs, also small, scarce, reddish, articulate, non-glandular hairs and, like the laminal parts, minute, club-like, mostly 2-celled hairs. Rachis gemmiferous at the tip, or at the insertion of a pinna, depending on the species, the gemma consisting of a small rosette of finger-like trophopods. Apices of lamina, etc. of gradually simpler structure, with confluent segments. Divisions of higher order, if present, anadromous. Ultimate segments unequal-sided, oblong-lanceolate, crenate to deeply pinnatifid. Veins free, ending well behind the margin. Sori terminal, roundish, exindusiate, consisting of rather few simultaneously maturing sporangia intermingled with cylindrical, few-celled trichomes with or without glandular end cell. Sporangial stalk 2- or 3-rowed, bearing some few-celled trichomes. Annulus interrupted by the stalk; stomium well-differentiated, of 2 cells. Spores trilete, tetrahedral-globose, with prominent angles, irregularly tuberculate, the tubercles beset with delicate echinae. Gametophyte (only known in M. subdigitatum) ribbon-like, lobed, the antheridia surrounding one or a few archegonia. All chromosome counts seem to be based on n = 56.