Woodsia obtusa

Woodsia obtusa (Spreng.) Torr.
(Latin: obtusa, blunt or dull, in reference to the tips of the pinnules)

Local names: bluntlobe cliff fern, common woodsia, blunt-lobe woodsia, large woodsia

Leaves semi-evergreen, clustered, erectascending, to 40(–60) cm tall, often smaller, the blades elliptic-lanceolate to broadly lanceolate, 2-pinnate or 2-pinnate-pinnatifid; indusia rather large, at first enclosing the sporangia and later splitting into several spreading, relatively broad, irregular, non-thread-like segments. Rocky areas, outcrops, well-drained, often sandy areas; Pineywoods w to Montague and Palo Pinto (W.H. Mahler 8318, BRIT) cos. in the Cross Timbers and Prairies, to Gillespie (O’Kennon 8364, BRIT), Mason (BRIT, TEX-LL), and McCullough (Turner et al. 2003) cos. in the e Edwards Plateau, and s to Gonzales Co. (Turner et al. 2003; Fleenor & Tabor 2009) in the Ottine wetlands (see discussion on page 36); se Canada and throughout e U.S. w to NE, OK, and TX. Sporulating Mar–Nov. Two subspecies of W. obtusa, differing in chromosome number, are recognized by Windham (1993d, 1993e) and are separated by him as in the key to subspecies below. Both are widespread in the e . of TX with var. occidentalis extending further w. Although some mature mid-season material can be clearly and consistently determined to subspecies, it is often difficult to distinguish many specimens. Windham (1993d) further indicated that the 2 subspecies hybridize in the area of sympatry and form sterile triploids with malformed spores. The county distribution map provided for TX does not distinguish subspecies. This species is very similar in general morphology to the rare Cystopteris protrusa, southern bladder fern, and can be confused with that species in the e . of TX. The two can be distinguished by the indusia and other characters (e.g., whether veins reach leaf margins) as given in the key to plants previously included in a more broadly conceived Woodsiaceae (page 307).

1. Spores averaging 42–47 μm [tetraploid]; proximal pinnules of lower pinnae usually shallowly lobed or merely dentate; blades coarsely cut and evidently 2-pinnate; rhizomes compact to short-creeping, individual branches usually 5–10 mm diam.________subsp. obtusa
1. Spores averaging 35–42 μm [diploid]; proximal pinnules of lower pinnae usually deeply lobed or pinnatifid; blades finely cut, 2-pinnate-pinnatifid; rhizomes short- to long-creeping, individual branches 3–5 mm diam.________subsp. occidentalis

subsp. obtusa
2n = 152 (tetraploid) (Windham 1993d). Widely scattered in East TX (e.g., Grayson, Hopkins, and Milam [S.L. Orzell & E.L. Bridges 6634] cos. [all BRIT]—identified J. Peck) w to e Cross Timbers and Prairies (Tarrant Co. [BRIT]); se Canada and e U.S. w to NE and e 1⁄3 of TX.

subsp. occidentalis Windham
(Latin: occidens, of the west)
2n = 76 (diploid) (Windham 1993d). Widespread in e . of TX (based on herbarium collections at BRIT, apparently more common in East TX than subsp. obtusa); also Cross Timbers and Prairies and e Edwards Plateau (e.g., Gillespie Co., Correll & Correll 12753, BRIT, annotated by M.D. Windham); AR, KS, MO, OK, and e 1⁄2 of TX.

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