Dennstaedtia globulifera

Dennstaedtia globulifera (Poir.) Hieron.
(Latin: globus, ball, sphere, or globe, and -ifera, a suffix from Latin fero, to bear, = globe-bearing, in reference to the globular sori)

Local names: beaded cuplet fern, southern hay-scented fern

Plant extremely large for a TX fern (leaves to nearly 4 m long); rhizomes long-creeping; leaves erect or arching; petioles to 1 m long; leaf blades 3(–4) pinnate, 1–3 m long, deltoid to ovate, ca. 2⁄3 to nearly as wide as long, the tissue soft-herbaceous, glabrous on upper surface, with hairs on the veins on lower surface, the ultimate leaf segments obtusely toothed to lobed with sinuses reaching to nearly ½ distance to midrib; sori distinct, globose, ca. (1–)1.2–1.5 mm in diam., marginal at vein tips in the sinuses (between teeth/lobes) of ultimate segments, with cup-like indusia, these formed by fusion of true indusium and tiny tooth of ultimate leaf segment; 2n = ca. 94 (Nauman & Evans 1993). Extremely rare in moist caves or limestone sinks (in other parts of its range, e.g., in Mexico, it is found in wet montane tropical forests); in the U.S. known only from Val Verde Co. (e of the Pecos River in extreme w Edwards Plateau), TX (first TX coll.: Larry Hoffman s.n., 1958, “Fern Cave”; Correll & Correll 26140, 1962; E. Glenn 19280, 1962, all TEX-LL); also Mexico, West Indies, Central and South America. Sporulating summer. [Dicksonia globulifera (Poir.) Kuntze, Polypodium globuliferum Poir.] Correll (1960a) reported this species as new to both TX and the U.S. According to label data by Correll (Correll & Correll 26140), the plant was growing “On floor of cave about 50 ft. deep, below opening.” As in the case of several other TX ferns (Seigler & Lockwood 1975; Seigler 1977), the TX occurrence of this largely tropical species is significantly disjunct from the majority of the species’ range. It is able to survive in w TX by occupying an extremely rare microhabitat—humid cave entrances. The extremely large leaves are very surprising to find in a fern in the dry sw U.S. where reduction in leaf size is the norm (see page 27); in fact, Nauman and Evans (1993) noted that this species is “among the largest ferns in the [North American] flora”—the original TX collection cited by Correll (1960a) described “fronds up to 13 ft. [3.96m] long.” The combination of the large leaf size and the cup-like indusia and globose sori is quite distinctive among TX ferns. Given its rareness and limited distribution in the state, we consider this species to be of conservation concern in TX.

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