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Selbyana 11: 66-118 THE VASCULAR FLORA OF LA SELVA BIOLOGICAL STATION, COSTA RICA* POLYPODIOPHYTA MICHAEL H. GRAYUM Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166 HUGH W. CHuRCHILL Department of Botany, University of Vermont, Burlington, Vermont 05405 GRAYUM, M. H. AND H. W. CHuRCHILL. 1989. The with a leafgap). The sporangia are generally borne vascular flora ofLa Selva Biological Station, Costa abaxially or marginally on ordinary or reduced Rica. Lycopodiophyta. Selbyana 11: 61-65. (See foliage leaves. Gametophytes typically free-living references listed there.) and photosynthetic. These are the true ferns, a STOIZE, R. O. 1976. Ferns and fern allies of Guate diverse and successful group with about 12,000 mala. Part I. Ophioglossaceae through Cyathea modem species (about two-thirds of which are ceae. Fieldiana, Bot. 39: 1-130. tropical). The group comprises innumerable Homosporous (ours), seedless vascular plants, growth forms, ranging from minute, thallose epi all with megaphylls (mostly large leaves with sev phytes or floating aquatics to giant tree-ferns; eral to many veins and the leaf trace associated both extremes occur at La Selva. KEy TO THE FAMILIES 1. Sterile leaf one per shoot, simple, entire, erect or folded in vernation (not circinate); sporangia large, thick walled, borne in two rows on a long-stalked spike subtended by the sterile leaf; small, terrestrial plants, very rare at La Selva. ....................................................... 1. OPHIOGLOSSACEAE. 1. Sterile leaves usually more than one, simple to compound, circinate in bud; sporangia borne on margin or abaxial surface of typical or modified foliage leaves; plants terrestrial, epilithic or epiphytic. 2. Sori in marginal, cuplike or tubular involucres; plants usually tiny to small, delicate epiphytes with the laminae thalloid to finely dissected and more or less translucent, one to few cell layers thick (if relatively coarse and/or terrestrial, then each involucre with a hairlike, exserted receptacle). ................. .. 4. HYMENOPHYLLACEAE. 2. Sori not in marginal, cuplike involucres or, ifso, the plants coarse and terrestrial; sori never with hairlike, exserted receptacles. 3. Frond axes dichotomously branched, pinnately narrow-lobed; plants terrestrial, the rhizome long- creeping. .......................................................... 3. GLEICHENIACEAE. 3. Frond axes not dichotomously branched or, if so, the plants epiphytic. 4. Stipulespresent at base of petioles; fronds dimorphic, pinnate, the rachis nodose; pinnae opposite; sporangia fused laterally into synangia, lacking an annulus. ............ 2. MARATTIACEAE. 4. Stipules lacking; fronds di- or monomorphic, simple to compound, the rachis not nodose; pinnae on compound leaves alternate or, rarely, opposite; sporangia distinct, annulate. 5. Annulus oblique, fully encircling the sporangium; plants usually arborescent, with distinct trunks more than 0.5 m tall in fertile individuals; fronds rarely pinnate or pinnate-pinnatifid, more frequently bipinnate-pinnatifid to 4-pinnate; petiole bases, trunks, etc., rarely unarmed, more typically spinose; sari (in ours) round, abaxial. 6. Fronds simply pinnate, the pinna margins entire or apically serrulate; rhizome stout, creep ing, densely covered with orangish trichomes, the plants completely scaleless and unarmed. ....... ..................... ... ............ ...... ... ...... 5. METAXYACEAE. 6. Fronds pinnate-pinnatifid to 4-pinnate; rhizome generally arborescent (rarely obsolete); plants (especially the petiole bases) always scaly, typically armed with spines (rarely un- armed)....................................................... 6. CYATHEACEAE. * ROBERT L. WILBUR, Flora Editor, Department of Botany, Duke University, Durham, North Carolina 27706. 66 1989] GRAYUM & CHURCHILL: FLORA OF LA SELVA-POLYPODIOPHYTA 67 5. Annulus vertical, interrupted by the stalk of the sporangium; rhizome creeping to erect, occa sionally subarborescent but only exceptionally (Diplazium striatastrum) more than 0.5 m tall; fronds simple to decompound; petioles, etc., spinose only in Hypolepis (with creeping rhizome); sori highly variable in shape, abaxial to marginal. ............... 7. POLYPODIACEAE. * * N.B.: If the orientation of the annulus cannot Very rare at La Selva, known from a few small be determined, two aberrant species of "tree populations in the grassy pejibaye clearing. ferns," Metaxya rostrata (Metaxyaceae) and Cy athea ursina (Cyatheaceae), will key out here. 2. MARATTIACEAE Since these are not separable from Polypodiaceae Terrestrial plants, generally with stout, erect by means of ordinary field characters, they are rhizomes and compound leaves. Leaves circinate included in the generic key for that family as well. in vernation, stipulate, the laminar axes and (usually) the petiole with swollen nodes. Sporan I.OPHIOGWSSACEAE gia abaxial, thick-walled, lacking annuli, coales cent into elongate (in ours) synangia. Small, terrestrial (at La Selva) herbs with short, A well circumscribed and distinctive family, subterranean rhizome. Sterile leafsolitary on the easily recognized by the fleshy stipules at the base shoot, not circinate in vernation, sessile to short of the petiole, swollen laminar nodes and synan stalked, simple to compound. Fertile segments gia. About seven genera, two indigenous in the one to several, non-foliaceous, spicate or panic New World. Both of these, Marattia Sw. and ulate, arising from the apex of a common stalk Danaea, occur in Costa Rica, though only the shared with the sterile lamina. Sporangia lacking latter is found at La Selva. M arattia, which dif an annulus, thick-walled, two-valved at matu fers from Danaea in its bi- to quadripinnate, rity. usually solitary leaves, occurs at higher eleva Three genera and about 50 species. Botrych tions. ium Sw. occurs mostly in Arctic and temperate regions and (as in Costa Rica) tropical moun tains; it differs from Ophioglossum in its decom 1. DANAEA J. E. Smith pound sterile and fertile laminae, and open ve UNDERwooD,L.M. 1909. Danaea.NorthAmer.Flora nation. 16: 17-21. 1. OPHIOGLOSSUM L. Leaves dimorphic, simple to (in ours) once pinnate. Veins free and closely parallel. Synangia GoMEZ P., L. D. 1976. Contribuciones a la pteridol mostly covering the abaxial surface of the fertile ogia costarricense. IX. El genero Ophioglossum en pinnae. Costa Rica. Brenesia 8: 85-95. A strictly neotropical genus of 20-30 species, Sterile lamina simple and entire (in ours) or ranging from Mexico to Bolivia and throughout coarsely palmately lobed, with reticulate vena the West Indies. About 9 species are known from tion. Fertile segments consisting of one (in ours) Costa Rica. to several stalked "spikes," bearing two rows of Research at La Selva by J. Sharpe (pers. comm.) coalescent sporangia. has shown the maturation of mature fronds in A pantropical and temperate genus of about all our species of Danaea to be markedly sea 25 species, five of which occur in Costa Rica. sonal. 1. Ophioglossum reticulatum L. KEy TO THE SPECIES Terrestrial plants forming small to large col 1. Fronds (lamina plus petiole) less than 40 cm long, onies. Rhizome 0.4-1.9 cm long, horizontal to often even-pinnate; very common. ........... erect, with one or occasionally two shoots. Com ............................. 5. D. wendlandii. mon stalk of sterile laminae and fertile segment 1. Fronds more than 40 cm long, always odd-pinnate; 3-12 cm long. Sterile lamina reniform to cor occasional to rare. 2. Petiole lacking leafless nodes; rhizome and base date, ovate or elliptic, 2-6.3 cm long and 0.8- of petiole magenta in cross-section. 4.3 cm broad, rounded to apiculate or subacute 3. Petiole of sterile fronds more than 73 cm apically, cuneate to truncate or cordate at base. long; largest sterile pinnae more than 5 cm Fertile segment 1.8-5.7 cm long and 2-3.5 mm wide; pinnae of mature fronds 14 pairs or wide, on a stalk 7-20.5 cm long. Southern Mex more; fertile fronds maturing in dry season ico to Bolivia and the West Indies, Old World (January-May); very rare. ............. tropics; widespread in Costa Rica from 0 to . .. 3. D. grandi/olia. 2,000m. 3. Petiole of sterile fronds less than 73 cm long; 68 SELBYANA [Volume 11 sterile pinnae less than 5 cm wide; pinnae just two populations: a large one along the Q. fewer than 14 pairs; fertile fronds maturing Pantano at about Line 2100, and a much smaller in the wet season (July-September); occa- one in the vicinity of CES 450. sional. .................. .4. D. nodosa. This rare fern is similar in most respects to 2. Petiole with 1-5 leafless nodes; rhizome and base Danaea nodosa, with which it has sometimes of petiole white in cross-section. 4. Sterile pinnae fewer than 7 pairs, broadly been lumped, but considerably larger; in life it elliptic, more than 2.5 cm wide, green below, appears as distinctive as do most species of Dan entire throughout; rhizome often briefly cau- aea. lescent; occasional. ....... 2. D. elliptica. 4. Sterile pinnae more than 7 pairs, linear-ob long, less than 2.5 cm wide, silvery-white 4. Danaea nodosa (L.) J. E. Smith below, serrulate toward apex; rhizome ob- Petiole 29-61 cm long. Sterile lamina about solete; very rare. ........ 1. D. cuspidata. 40-70 cm long, generally with 6-13 pairs of pin nae. Sterile pinnae narrowly elliptic or oblong, 1. Danaea cuspidata Liebm. 18-26(-35) cm long, 2.5-3.5 cm wide, entire or (=D. munchii Christ) bluntly serrulate and acuminate apically. Fertile pinnae about as long, but narrower. The fertile Petiole 17-44 cm long. Sterile lamina 30-60 fronds mature from July to September. Southern cm long, with 8-18 pairs ofpinnae. Sterile pinnae Mexico to Brazil, West Indies; from 0 to 1, 100 linear to narrowly oblong, silvery below, strongly m in Costa Rica, on both slopes. serrulate and acuminate apically, 9-16 cm long, Occasional at La Selva, usually in low, damp 1.5-2.5 cm wide. Fertile pinnae linear, 4-8 cm areas in primary forest. long, 4-8 mm wide. The fertile fronds mature from January to March. Oaxaca to Panama; the most widespread Danaea in Costa Rica, ranging 5. Danaea wendlandii Reichb. f. from 0 to 2,300 m.