Dennstaedtia spinosa
Description
Rhizomes creeping, unbranched, clothed with black hairs; fronds nearly 2 m long; axes stramineous, spiny and pubescent, the spines to 3 mm long, straight or slightly antrorse; stipes ca. 1⁄2 the frond length, buds at bases not seen, but expected; blades ca. approx. 1 X 1 m, deltate, quadripinnate-pinnnatifid, lacy; pinnae alternate, short-petiolulate to 12 mm; basal pinnules opposite, not or only slightly reduced, the larger 10–13 X 2.5–3 cm; laminae hirsute abaxially with straight, hyaline hairs, lustrous adaxially and nearly glabrous except on costal wings and major veins; laminar grooves not continuous, with vertical wings adaxially; vein ends slender, clavate; indusia ca. 0.6 mm deep, 0.5–0.8 mm wide, entire to irregularly dentate, low, broader than high, more or less bivalvate.B
B. Mickel, J. T. & Smith, A. R. 2004: The Pteridophytes of Mexico Vol. 88
Discussion
This species closely resembles D. cicutaria s.l. , but can be distinguished readily by the spiny axes and finer blade dissection. Both species have dicyclic solenostelic rhizomes, but the steles of D. spinosa are terete and uncorrugated. The spores of D. cicutaria are verrucate, whereas those of D. spinosa have low, irregularly anastomosing ridges. Furthermore, the indusia of D. spinosa are more regularly dentate than those of D. cicutaria. Although D. cicutaria occasionally has a few prickles on its axes, and a few specimens described as D. decomposita Christ are as dissected as D. spinosa, no specimens have the regular and consistent spininess or the anatomical and spore characteristics of D. spinosa.C
C. Mickel, J. T. & Smith, A. R. 2004: The Pteridophytes of Mexico Vol. 88
Specimen
Chis (Breedlove 57862, CAS, ENCB).E
E. Mickel, J. T. & Smith, A. R. 2004: The Pteridophytes of Mexico Vol. 88
Synonymy
Dennstaedtia spinosa, Amer. Fern J. 58(2): 90. 1968