Thelypteris interrupta
Thelypteridaceae
Hottentot fern, spready tri-vein fern, Willdenow's fern, Willdenow's maiden fern
marsh fern family, thelypteris family
long-creeping, cordlike, 3–6 mm diam.
creeping to erect, scaly at apex.
monomorphic, evergreen, 3–6 cm apart, 50–150(–250) cm.
monomorphic or somewhat dimorphic [dimorphic].
straw-colored to tan, 20–125 cm × 3–6 mm, scaleless.
in cross section with 2 crescent-shaped vascular bundles at base.
30–125 cm, broadest at base, gradually narrowed distally to pinnatifid apex.
pinnate to pinnate-pinnatifid, rarely more than 2-pinnate [simple];
rachis grooved adaxially or not, grooves not continuous with grooves of next order.
7–30 × 1–2 cm, incised 1/3–1/2(–3/5) of width;
segments deltate, rounded to acute;
proximal pair of veins from adjacent segments united at acute or obtuse angle below sinus, with excurrent vein 2–4 mm.
free or anastomosing, running to margin, areoles with or without included free veinlets.
round, medial to supramedial;
indusia tan, glabrous to hairy;
sporangia with red- or orange-capped, stalked, globose glands arising from sporangial stalks.
inframedial to supramedial, occasionally nearly marginal, round or oblong, rarely elongate along veins;
indusia reniform or sometimes absent.
bilateral, monolete [rarely globose-tetrahedral and trilete], usually with a prominent, crested, echinate, or reticulate perispore.
green, cordate, usually hairy or glandular;
antheridia 3-celled.
abaxially of hairs 0.1–0.3 mm on costae and veins, or hairs often lacking, costae also with tan, ovate scales;
veins, costules, and costae adaxially glabrous or sparsely pubescent;
blade tissue without hairs on both sides, or hairy abaxially, usually with red to orange, shiny, sessile, hemispheric glands abaxially.
of transparent, needlelike, hooked, septate, or stellate hairs, or rarely hairs lacking.
= 144.
Thelypteris interrupta
Thelypteridaceae
D. B. Lellinger (1985) applied the name Thelypteris interrupta to specimens from India, while using T. totta (type from South Africa) for North American and South American specimens. Diploid cytotypes are known from Africa and Asia, whereas all counts from the Neotropics are tetraploid. Until more counts are available and the morphologic variation (chiefly in glands, pubescence, and leaf size) in this species complex is better understood, I prefer to circumscribe the species broadly.
R. E. Holttum (1982) circumscribed Cyclosorus (as a genus) to include this species and one or two others.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Members of Thelypteridaceae have historically been associated with Dryopteridaceae (in particular, Dryopteris) but in fact have no close relationship with that family. Thelypteris and allies differ from Dryopteris and allies by their indument of transparent needlelike hairs (versus needlelike hairs absent in Dryopteridaceae); general absence of blade scales (versus blade scales often present); petiole vasculature in cross section with two crescent-shaped bundles (versus many round bundles arranged in an arc, Athyrium and allies exceptional); generally 1-pinnate to pinnate-pinnatifid blades (versus often more divided); veins usually not forking in the ultimate segments (versus often forking); adaxial grooves discontinuous from rachis to costae, or grooves lacking (versus grooves often continuous); and chromosome base numbers from 27–36 (versus generally 40, 41).
Genera 1 to ca. 30, depending on circumscription, species ca. 900 (as circumscribed here, 3 genera and 25 species in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Blades 1-pinnate to deeply pinnate-pinnatifid; costae grooved adaxially; veins meeting margin at or above sinus or united below sinus. | Thelypteris |
1. Blades 2-pinnatifid, with pinnae at least in distal 1/2 of blade connected by wings along rachis, or blades 2-pinnate-pinnatifid; costae not grooved adaxially; veins commonly meeting margin above sinus. | → 2 |
2. Pinnae free, rachis not winged; blades 2-pinnate or more divided; costal hairs septate, often longer than 1 mm; indusia small, less than 0.3 mm diam. | Macrothelypteris |
2. Pinnae mostly connected by wings along rachis, the wings often forming semicircular lobes between pinnae; blades 2-pinnatifid; costal hairs not septate, shorter than 0.5 mm; indusia absent. | Phegopteris |
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