BARRO COLORADO ISLAND
INTRODUCTION 63 INTRODUCTION 63
1. SELAGINELLACEAE Heterosporous annuals or perennials with adventitious
roots. Leaves 1-veined, usually dimorphic in 4 ranks, with a minute ligule at base of each leaf. Strobili usually 4-sided, consisting of imbricated megasporophylls at base and microsporophylls at apex; sporangia 1-chambered, containing (in axils of sporophylls) either microspores or megaspores; prothallia very small, unisexual.
Members of the family are distinguished by their minute dimorphic leaves, usually all held in a single plane such that the plant often looks like a single, lacy, highly dissected, compound leaf. The four-sided, cone- like strobili are also a distinguishing character of the Selaginellaceae.
Dispersal may be in part by rain water, which washes away the megacarps (van der Fiji, 1968).
One genus, with about 700 species; tropical, subtropi- cal, and temperate regions.
SELAGINELLA Beauv.
Selaginella arthritica Alston, Arch. Bot (Forli) 11:43.1935
5. conduplicata sensu Spring.
Terrestrial, usually 15-40 cm tall, glabrous; lower parts of stems in aduk plants usually creeping, densely rooted, and leafless, the stems becoming erect and sparsely leafy and flexuous near apex, at least the larger stems swollen and markedly articulate, the lateral branches sparse, only the lower few of noticeable length. Median leaves auricu- late, appearing aflixed well above base, acute at apex, entire; lateral leaves ovate-oblong, acute to blunt at apex, not or weakly auriculate, to ca 5 mm long; lower stem leaves auriculate. Cones 1 mm wide, mostly 5-15 mm long, usually solitary, rarely 2-4 at apex of ultimate branches, sharply square; megaspores few, smooth, light brown. Croat 8614.
KEY TO THE SPECIES OF SELAGINELLA
Plants ± erect, usually more than 20 cm tall; main stem not branched from near base-
Plants usually less than 40 cm tall, usually creeping; stems glabrous and markedly articulate, usually with few lateral branches (less than 4); plants abundant; fertile parts ca 1 mn^
wide, sharply square ^ arthritica Alston Plants usually 1 m or more tall, erect, then arching, stems pubescent, not markedly articulate
usually with many lateral branches; plants rare; fertile parts ca 2 mm wide, irregular, + Plants scandent or decumbent, usually less 'than 20 cm taU; main stem usually Wh^Smnea^r""^'
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Fig. 1. Selaginella haematodes Fig. 2. Selaginella mollis
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Fig. 3. Lycopodium dichotomum
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SELAGINELLACEAE/SELAGINELLA69
Leaves conspicuously ciliate (at least the base of the lateral leaves):
Both lateral and stem leaves auriculate, usually appearing affixed well above base; lateral leaves usually more than 2.5 mm long; plants usually long-creeping 5. horizontalis (Presl) Spring.
Leaves not auriculate, clearly basifixed; lateral leaves less than 2 mm long; plants short, not creeping 5. mollis A. Braun Leaves entire or merely short-toothed, not ciliate:
Stems markedly articulate, never flagelliform at apex of main stem; largest lateral leaves 3.5-5 mm long, entire; median leaves markedly auriculate, appearing affixed well above base ..
5. arthritica Alston Stems not articulate, usually flagelliform at apex; largest lateral leaves usually less than 2 mm
long, inconspicuously toothed; median leaves not auriculate, basifixed 5. fiagellata Spring.
Very abundant throughout the forest, especially along trails.
Juvenile forms often have long-creeping, sparsely leafy stems and much narrower, erect, leafy portions.
Nicaragua to Panama; to 1,700 m elevation. In Panama, known from tropical moist forest in the Canal Zone (BCI only), Bocas del Toro (Shepherd Island), and Darien, and from tropical wet forest in Panama (Cerro Trinidad).
Selaginella exaltata (Kunze) Spring., Bull. Acad. Roy.
Sci. Bruxelles 10:234. 1843
Terrestrial, to 1 m or more tall, erect or frequently arch- ing and scandent; main stem articulate, glabrous or pu- bescent, sparsely leafy, the smaller stems inarticulate, more closely leafy, usually with short, stiff trichomes.
Median leaves asymmetrical, sharply long-acuminate, decurrent at base, entire; lateral leaves ± oblong, sharply acuminate, basifixed, 2-4 mm long, entire; leaves on main and secondary stems sparsely spaced, to 1 cm long, mark- edly auriculate. Cones terete to squarish at apices of ultimate branches; megaspores prominently white-ruffled.
Shattuck 1158, Croat 16193.
Rare, in ravines in the old forest.
Standley reported 5. conduplicata Spring., a synonym of 5. arthritica. This report may have been based on a misdetermination of Shattuck 1158, which is this species.
Panama to Peru. In Panama, known from tropical moist forest in the Canal Zone, San Bias, and Darien, from pre- montane wet forest in Colon, and from premontane rain forest in Darien.
Selaginella fiagellata Spring., Bull. Acad. Roy. Sci.
Bruxelles 10:228. 1843
Terrestrial, small and creeping, glabrous; stems moder- ately weak, not articulate, the lower part leafy, the apical part long-flagellate, sparsely short-branched. Median leaves abruptly and sharply long-acuminate, basifixed and decurrent, not auriculate, the margins inconspic- uously toothed and often appearing hyaline; lateral leaves
± ovate-oblong, usually less than 2 mm long, acute to weakly acuminate, not auriculate, the margins inconspic- uously toothed. Cones ± inconspicuous, merging with leaves; megaspores minute, white, smooth. Croat 4098, 6467.
Infrequent in the forest, usually on trails, sometimes growing on rocks.
Mexico to Bolivia and French Guiana. In Panama, known only from tropical moist forest in the Canal Zone and Panama.
Selaginella haematodes (Kunze) Spring, in Mart., Fl.Brasil. 1(2):126. 1840
Terrestrial, erect, to 80 cm tall and to 35 cm wide, un- branched in lower half, reddish near base, not articulate, sparsely leafy, regularly branched from near middle, the branches 12-25 cm long, gradually diminished in length toward apex. Leaves uniform, reddish, basifixed, ovate- oblong, usually acute; median leaves gradually long- acuminate, basifixed, minutely toothed; lateral leaves ovate-oblong, acute at apex, basifixed, minutely toothed.
Cones numerous, solitary at branch apices, mostly to ca 1 cm long, ± square, the bracts long-acuminate and
± spreading; megaspores minute, white, smooth. Croat 4111.
Locally abtindant along trails near streams; less fre- quent elsewhere in the forest.
Easily distinguished by the reddish stem, large size, and triangular blade.
Panama to Bolivia. In Panama, known from tropical moist forest in the Canal Zone, Panama, and Darien, and from premontane wet and tropical wet forests in Panama.
See Fig. 1.
Selaginella horizontalis (Presl) Spring., Bull. Acad.
Roy. Sci. Bruxelles 10:226. 1843 5. fendleri Baker; 5. sylvatica Baker
Terrestrial, usually long-creeping and ± regularly short- branched; stems obscurely articulate, lacking flagellate apices, glabrous, prominently rooted along their length, the roots produced from bottom side of stem. Median leaves acuminate, auriculate, and affixed well above base, markedly ciliate at base; lateral leaves ± oblong, 3-4 mm long, acute at apex, auriculate at base, the basal part markedly long-ciliate. Cones short, inconspicuous, soli- tary at apices of ultimate branches, squarish, the bracts long-tapered, spreading, minutely toothed; megaspores minute, alveolate, light yellow-brown. Croat 6933, 12670.
70
LYCOPODOPHYTAAbundant in the forest, usually along trails; also found in shaded places in clearings.
Costa Rica to Colombia. In Panama, known from tropical moist forest in the Canal Zone and Panama.
Selaginella mollis A. Braun, Ann. Sci. Nat. Bot., ser.
5,3:276. 1865 5. schrammii Hieron.
Terrestrial, creeping or appressed, minute, usually less than 10 cm long, glabrous except for long cilia on lower part of leaves; stems not flagellate at apex, leafy through- out at base, short-branched almost throughout, the branches nearly equal in length. Median leaves not much smaller than lateral leaves, ± ovate, abruptly acu- minate, short-toothed near apex, ciliate toward base, not auriculate, basifixed; lateral leaves ± oblong, usually acute at apex, not auriculate, basifixed, to ca 2 mm long, prominently long-ciliate at least near base. Cones incon- spicuous, constituting a gradual continuation of branch apices, the bracts short-toothed; megaspores minute.
Croat 10759.
Rare, in the forest, usually on steep shaded banks.
Mexico to Panama and Colombia. In Panama, known from tropical moist forest in the Canal Zone, Bocas del Toro, and Panama and from premontane wet forest in Panama.
See Fig. 2.