Elaphoglossum
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Authority
Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
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Family
Dryopteridaceae
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Scientific Name
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Description
Genus Description - Plants generally epiphytic in wet montane forests and evergreen cloud forests, a greater pecentage terrestrial at high elevations; rhizome short- to long-creeping, rarely erect, slender to stout (1-15 mm diam.); rhizome scales orange to black, basally attached or peltate, entire to toothed; fronds 2200 cm long, erect, spreading or pendent, simple (pedate in one South American species); stipe glabrous or scaly, sometimes also with minute glandular hairs, long or very short, base often darker (phyllopodium) with abscission at its upper demarcation rather than at the rhizome; blade linear to ovate or oblanceolate, apex acuminate or caudate to obtuse, base rounded to long-attenuate; midvein grooved adaxially, usually with scales of the stipe abaxially; veins generally free, rarely netted or with a marginal commissural vein, simple to twice-forked, ending near the margin, those stopping well short of the margin usually end in conspicuous hydathodes; blade scales sometimes differing from those of the rhizome or stipe, abundant to lacking, often greatly reduced and appearing as stellate hairs; fertile fronds longer or shorter than the sterile fronds but generally with narrowed blades and proportionally longer stipes; fertile blade completely covered beneath with sporangia (acrostichoid sori); sporangia long-stalked, the annulus erect, interrupted by the stalk; paraphyses in some species but generally lacking; spores bilateral, monolete, most with high crests or low ridges, but some echinate or verruculate without ridges or crests.
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Discussion
Type: Elaphoglossum conforme Schott ex J. Smith. Aconiopteris Presl, Tent, pterid. 236. 1836. Type: Aconiopteris subdiaphana (Hooker & Greville) Presl [=Acrostichum subdiaphanum Hooker & Greville, = Elaphoglossum nervosum (Bory) Christ]. Hymenodium Fée, Mém. foug. 2: 20, 80. 1845. Type: Hymenodium crinitum (Linnaeus) Fée [=Acrostichum crinitum Linnaeus, =Elaphoglossum crinitum (Linnaeus) Christ]. There are probably well over 500 species in Elaphoglossum, about three-fourths of them occurring in tropical America. There are 36 species recognized in Oaxaca, although our knowledge of them is far from complete. Several are known from only one or a few specimens. The genus is very difficult taxonomically. There are many species and few differentiating characters, and the genus has not been adequately treated with a usable subgeneric breakdown until recently. Variation of the characters, such as plant size, blade form, scale color, scaly type, is not fully understood in terms of species delimitation. The characters lie mostly in the scales of the rhizome and blade. The fertile fronds add characters of relative size, intersporangial scales, and spore details, but virtually all the species can be identified on the basis of vegetative material alone. Un- fortunately, collectors are hesitant to collect sterile material and thus many records have gone uncollected. In the following descriptions, the rhizome diameter is given excluding the scale covering. The rhizome scales may be appressed or widely spreading and might too greatly distort the rhizome diameter measurements were they included. Stipe bases are differentiated into evident phyllopodia in some but not all species. Blade texture is difficult to determine on the basis of dried material and is given only for those species in which it is clearly distinctive. Although the veins seem to run to the margin in some species, they end just short of it, leaving a pale, thin margin 0.5-1 mm wide, which is often difficult to distinguish, especially in very coriaceous or heavily indumented fronds. This margin is more readily distinguished in the fertile fronds where it remains sterile in contrast to the acrostichoid sorus of the rest of the lower surface. Vein angles and intervein distances are measured at mid-leaf, half way between the midvein and margin. The scales of the rhizome and blade are generally quite distinct from one another, and on the stipe they intergrade or in some cases remain distinct and occur together. The blade scales, although basically the same type on upper and lower surfaces, are more highly dissected abaxially. In some this means longer teeth, but in more extreme cases they are reduced to stellate hairs or even to resinous dots. In subglabrous fronds, the blade scales are reduced further in size to minute stellate hairs that are visible only with a hand lens. On the fertile blade, the upper surface scales are similar to those of the sterile blade, but abaxially the scales are generally limited to the midvein and in only a few species are there scales among the sporangia. Another type of indument is minute erect glandular hairs, which are found in varying degrees on the stipe and occasionally on the blade in Elaphoglossum lindenii, E. erinaceum, E. tambillense, and their relatives outside of Oaxaca. Elaphoglossum is distinct by its simple blade, generally with free veins, and acrostichoid sori. Reference: Mickel, J. T. & L. Atehortua G. 1980. Subdivision of the genus Elaphoglossum. Amer. Fern J. 70: 47-68.