Monographs Details: Thelypteris hispidula (Decne.) C.F.Reed
Authority: Proctor, George R. 1989. Ferns of Puerto Rico and the Virgin Islands. Mem. New York Bot. Gard. 53: 1-389.
Family:Thelypteridaceae
Description:Species Description - Rhizome short, erect, 3-5 mm thick (excluding root mass and tightly adhering stipe bases), bearing at apex a tuft of linear-lanceolate, lustrous dark brown to castaneous scales 3-6(-8) mm long and less than 0.7 mm wide, minutely ciliate and often with a few tiny hairs on the surfaces. Fronds spreading, not dimorphic; stipes mostly 10-40 cm long, straw-colored, sometimes darkened at base, pubescent and with a few scales near base. Blades oblong-elliptic or oblanceolate, 18-55(-75) cm long, 7-32 cm broad, tapering evenly to the short, pinnatifid apex; largest pinnae 3.5-16 cm long, mostly 0.8-2 cm wide (excluding enlarged basal segments), sessile, pinnatifid; segments oblong, slightly oblique or sometimes subfalcate, mostly ca. 3 mm wide, entire or minutely crenulate toward apex; veins usually 5-9 pairs, simple except in enlarged basal segments. Sori about medial; indusium orbicular-reniform, densely pubescent; sporangia glabrous but their stalks often bearing minute stipitate glands.

Discussion:

Basionym. Aspidium hispidulum Decaisne, Nouv. Ann. Mus. Hist. N a t 3: 346. 1835.

Type. Guichenot, from Timor (P, not seen).

Syn. Nephrodium quadrangulare Fee, Mem. foug, 5: 308, 1852, (Type, Leprieur, from French Guiana, NY, isotype.)

Bryopteris quadrangularis (Fee) Alston ex Box & Alston, J. Bot. 75: 253. 1937.

Cyclosorus quadrangularis (Fee) Tardieu-Blot, Notul. Syst. (Paris) 14: 345. 1953.

Thelypteris quadrangularis (Fee) Schelpe, J. S. African Bot. 30: 196. 1964.

Two varieties of this variable species have been found in Puerto Rico, These can usually be distinguished as follows:

a. Basal veins of adjacent segments united below the sinus, giving forth an excurrent veinlet leading to or toward the sinus.

b. Fronds usually more than 60 cm long; blade less than twice as long as stipe, and with only I or 2 pairs of slightly reduced proximal pinnae; tissue usually hairy on adaxial side. ...

18a. var. hispidula. b. Fronds usually less than 60 cm long; blade 2- 4 times as long as stipe, and with several pairs of gradually reduced proximal pinnae; tissue usually lacking hairs on adaxial side

18b. var. inconstans.

a. Basal veins of adjacent segments free or connivent at or near the sinus, or else some free and some joined

18b. var. inconstans.