Thelypteridaceae

Caudex erect, short-creeping or long-creeping, rarely scandent; vascular structure in all cases a radially symmetrical dictyostele; scales usually thin, not peltate, in almost all cases bearing both marginal and superficial Unicellular hairs which are either acicular or glandular. Vascular strands at base of stipe 2, linear in section (rarely with an additional pair of small ones), uniting upwards to a U-shape; a linear aerophore with stomata continuous along each side of stipe and rachis. Fronds usually pinnate with crenate or lobed pinnae, in a few cases simple or bipinnate, never with basiscopically enlarged basal pinnae; apical lamina usually triangular and lobed, grading into upper pinnae, in some cases pinna-like; lower pinnae in many cases gradually much reduced or with abrupt transition to a series of small rudiments; a small aerophore, sometimes swollen or elongate, present at the base of each pinna; a translucent membrane present in the base of each sinus between adjacent pinna-lobes; venation in each pinna consisting a costa bearing costules, each costule bearing pinnately-arranged veins in a pinna-lobe; veins free in deeply lobed pinnae, or basal veins in adjacent lobes anastomosing to form an excurrent vein, which may be joined by other veins, terminating at the base of a sinus-membrane, successive veins Passing to the sides of the sinus-membrane where this is elongate. Indument: scales always present at base of stipe, gradually smaller upwards, uunute (often consisting of a single row of cells) on the distal parts of fronds, often nearly all caducous; adaxial surface of rachis and costae a'ways bearing antrorsely curved acicular unicellular hairs, in a few cases a'so septate acicular hairs; abaxial surface of rachis and costae usually bearing a different indument consisting of more slender unicellular acicular and/or glandular hairs or sessile glands of various forms (forked hairs in Ampelopteris only); surface of lamina between veins either quite glabrous or more often with a distinctive complement of hairs and glands different adaxially and abaxially. Sori borne on abaxial surface of veins, orbicular or sometimes elongate, indusiate or not; indusia reniform, glabrous or bearing hairs and/or glands, in some cases very small, athyrioid in some species of Coryphopteris; sporangia sometimes bearing glands or short acicular hairs (setae) near annulus, often with a hair of distinctive form on the sporangium-stalk; spores in almost all cases monolete, with perispore of varied form, in Trigonospora trilete. Gametophyte in all cases symmetrical-cordate, with unicellular chlorophyllous hairs on all parts, these hairs with ± swollen rounded tips which become wax-encrusted; in most cases, usually as a late development, unicellular acicular hairs, comparable with those on the sporophyte, may occur; other types of hair may be distinctive of some genera. Distribution. Throughout the tropics, especially in wetter areas; species few in temperate regions (5 in Europe), almost 1000 in all. The majority are terrestrial ferns of forest, but a few (especially in Christella few and Macrothelypteris) occur in open places only, and a (Cyclosorus, Thelypteris) in open swamps; some are adapted to grow on rocks by streams; very few are scandent; a few are casually epiphytic.