Manual de Plantas de Costa Rica 173 
ceus, Sloanea laurifolia, Socratea exorrhiza, Syngonium hastiferum, Tachigali versi- 
color, Vantanea barbourii, and Virola surinamensis. As pointed out by Hartshorn (1983), 
because of the massive deforestation of the southern Pacific part of Costa Rica in re- 
cent years, many of these species can now be seen commonly only in Corcovado Na- 
tional Park, and other protected areas in the near vicinity. 
The destruction of these forests has gone on since well before Paul Allen’s arrival 
(Allen, 1956). Some of them were eliminated to make room for the large and growing 
pineapple industry. Nevertheless, from what little remains we know that the combina- 
tion of species here is very interesting phytogeographically, and unique in Costa Rica. 
Here are found some nearly extinct habitats, such as the small lagoon at the entrance to 
Buenos Aires with perhaps a greater diversity of aquatic plants than anywhere else in 
the country (Crow, 1993). Toward the southeast, where the Rio General and Rio Coto 
Brus join, the climate is hotter and drier due in part to the rain-shadow effect of the Fila 
Costefia; this, along with soil conditions, gives rise to some rather large tracts of wood- 
land savanna. These sites are dominated by such species as Acrocomia aculeata, Andro- 
pogon angustatus, A. leucostachyus, Attalea rostrata, Ayapana amygdalina, Byrsonima 
crassifolia, Calea urticifolia, Calycolpus warszewiczianus, Chamaecrista desvauxii, 
Clidemia sericea, Cochlospermum vitifolium, Curatella americana, Davilla kunthii, 
Declieuxia fruticosa, Hyptis brachiata, Melochia villosa, Miconia albicans, M. rubigi- 
nosa, Mimosa debilis, M. somnians, Palicourea triphylla, Paspalum pectinatum, Psid- 
ium guineense, Roupala montana, Schefflera morototoni, Tephrosia nitens, and Xylopia 
aromatica. This ecosystem is what Gémez P. (1986) called the “moist savanna,” which 
in Costa Rica lacks Quercus oleoides but has a high density of Attalea rostrata, and 
much in common with South American savannas. 
In the driest sites of this valley, especially in the narrowest part of the Rio Grande 
de Térraba gorge, numerous species are found that are otherwise only known (in Costa 
Rica) from similar soils and climates of the dry forest of northwestern Guanacaste. A 
recent study of the vegetation of the lower Rio Grande de Térraba basin (INBio, 2000) 
found ca. 70 species with populations disjunct between these two sites, just as other 
species were found disjunct between Guanacaste and the Rio Grande de Candelaria. 
The most conspicuous savanna element in these dry areas 1s Curatella americana; oth- 
ers typical of the northern dry forests are Acacia centralis, A. polyphylla, Acanthoce- 
reus tetragonus, Agave angustifolia, Alvaradoa amorphoides, Andropogon angustatus, 
A. leucostachyus, A. virgatus, Aristida ternipes, Axonopus aureus, Ayapana amygda- 
lina, Ayenia micrantha, Bernardia nicaraguensis, Bromelia karatas*, Bulbostylis jun- 
coides, Capparis verrucosa, Chomelia spinosa, Clitoria glaberrima, Cnidoscolus tubu- 
losus, Coccoloba guanacastensis, Colubrina triflora, Declieuxia fruticosa, Dicliptera 
3 Bromelia karatas L. (Sp. pl. 285. 1753) is the correct name for the species called B. plumieri (E. Mor- 
ren) L. B. Sm. (an illegitimate name) in Volume II of the Manual; see Grant & Zijlstra (1998: 102). 
