Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.
Dryopteridaceae
Species Description - Rhizomes short- to moderately creeping, to 4 mm diam.; rhizome scales linear-lanceolate, dark brown to black, lustrous, entire to only faintly toothed, ca. 5 mm long; fronds clumped, 8-20(-30) x 0.8-1.2(-3) cm; phyllopodia distinct to indistinct; stipes 1/3-2/3 the frond length, with scales linear-lanceolate and darktoothed or dark-tipped, spreading, 3 mm long, some more dissected, like stellate hairs, appressed; blades narrowly elliptic, chartaceous, apices acute to acuminate, bases narrowly cuneate; veins obscure, free, simple or once-forked, 0.6-1 mm apart, at 55-65º angle to costa; hydathodes absent; blade scales evenly and liberally distributed adaxially but not overlapping, linearlanceolate, 1-1.5 mm long, with short hair-teeth, on abaxial surfaces less abundant, often folded lengthwise and curved; fertile fronds generally longer than the sterile and very long-stiped (ca. 5/6 the length), apices more acute or obtuse, bases more broadly cuneate, scales on abaxial costae but not among the sporangia.
Acrostichum gratum Fe´e, Me´m. Foug. 8: 69. 1857. Lectotype (chosen by Mickel in Davidse et al, 1995: 267). Mexico. Me´xico: Popocate´petl, Schaffner 279 (P!; isotype RB).
Acrostichum callolepis Fe´e, Me´m. Foug. 8: 69. 1857. Elaphoglossum callolepis (Fe´e) T. Moore, Index Fil. 7. 1857. Type. Mexico. Galeotti s.n. (P?). Acrostichum deppei Kunze ex Christ, Monogr. Elaph. 18. 1899. Type. Mexico. Schaffner s.n. [76]. (P!).
Elaphoglossum gratum is closely allied to E. hartwegii and E. pringlei. It is somewhat like E. muelleri, which is also scaly, terrestrial, and of high elevations, but can be distinguished by its linear-lanceolate, coarsely toothed blade scales. Elaphoglossum muelleri has blade scales with little body to them and the rhizome scales are tan to orange. Elaphoglossum gratum also resembles E. petiolatum, which has entire rhizome scales, and the adaxial blade scales are usually substellate rather than linear-lanceolate. Elaphoglossum gratum is close to E. hartwegii in its heavier scaliness on adaxial blade surfaces, dark entire rhizome scales, and tendency for the rhizomes to creep, but E. hartwegii has longer creeping rhizomes, and blade scales that are more deltatelanceolate and subentire, broader with darker middle, and pale margins rather than the usual white. Both may have the resin dots on the abaxial blade surfaces.
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