Monographs Details: Lastreopsis
Authority: Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
Description:Genus Description - Terrestrial, rarely epiphytic (ours); rhizome short- to long-creeping or erect, scaly; stipe scaly at base, with two prominent ridges on upper side, the channel between them with abundant short, erect, ctenitoid hairs (short, articulated, unbranched, catenate, reddish), rachis with similar channel continuous with channels of costae, ridges continuous with thickened margin of ultimate segments; fronds monomorphic, clumped, decompound, 3-4 times pinnate, rarely 2-pinnate, pentagonal, lowest pinnae exaggerated basiscopically in some species (ours), pinnae catadromous, apex pinnatifid; buds near apex of rachis or pinna rachises present in many species (ours); veins free, simple or forking; lamina firm-herbaceous with glandular hairs on lower surface; sori orbicular, rarely slightly oblong, indusiate or exindusiate, indusium reniform; sporangia often with 1-2 stalked glands on pedicel; spores bilateral with cristate perispore.
Discussion:Type: Lastreopsis recedens (J. Smith ex Moore) Ching [=Lastrea recedens J. Smith ex Moore, = Lastreopsis teñera (R. Brown) Tindale].
Parapolystichum (Keyserling) Ching, Sunyatsenia 5: 239. 1940. Polystichum sect. Parapolystichum Keyserling, Polyp, herb, bunge. 11, 45. 1873. Type: Parapolystichum effusum (Swartz) Ching [=Polypodium effusum Swartz, = Lastreopsis effusa (Swartz) Tindale].
Lastreopsis is a pantropical genus of about 33 species of temperate and rain forest regions, of which five to six are American, and only two in Oaxaca. It seems to be closest to Ctenitis, with which it shares the characteristic ctenitoid hairs and dissected fronds. The configuration of the ridges on the minor axes and rachis in Lastreopsis is distinctive; in Ctenitis such ridges are lacking or if present they are interrupted, and not decurrent onto the axes above or below.
References: Christensen, C. 1920. A monograph of the genus Dryopteris. Part II. The tropical American bipinnate-decompound species. Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Afd. VIII, 6: 1-132; Tindale, M. 1965. A monograph of the genus Lastreopsis Ching. Contr. New South Wales Natl. Herb. 3: 249339, t. 9-23, map.