Flora of North America species comparison

long- to short-creeping, branched or not, bearing scales and few to numerous roots, usually dictyostelic.

monomorphic to dimorphic, circinate in bud.

usually articulate at base [rarely nonarticulate, as in Loxogramme], lacking scales or sometimes scaly, with usually 3 vascular bundles.

simple to often pinnatifid, pinnatisect, or pinnate, infrequently more divided;

rachis grooved or not adaxially.

free (and simple to several times forked) to often anastomosing in complex systems, areoles with or without included veinlets.

borne abaxially on veins, round to oblong, occasionally elongate, rarely marginal, rarely covering surface;

paraphyses present or absent;

sporangia with stalk of 2 or 3 rows of cells;

indusia absent.

usually transparent or yellowish (rarely greenish), all 1 kind, bilateral, monolete [rarely trilete, as in some Loxogramme], surface most often smooth, tuberculate, verrucose, or granulate, occasionally spiny, 64 per sporangium (spores globose and 32 per sporangium in apogamous spp.).

green, aboveground, cordate or elliptic, glabrous or sometimes glandular;

archegonia and antheridia borne on lower surface, antheridia 3-celled.

on blade absent, or petiole, rachis, costae, and sometimes blade tissue usually bearing hairs (these often septate and with reddish crosswalls) and/or scales.