Manual de Plantas de Costa Rica 141 
abundant species as Bravaisia integerrima, Calathea crotalifera, C. lutea, Calyptro- 
gyne ghiesbreghtiana, Cyclanthus bipartitus, Pentaclethra macroloba, Pterocarpus of- 
ficinalis, Spathiphyllum friedrichsthalii, S. laeve, Terminalia oblonga, and Urospatha 
grandis. However, the yolillales (swamps dominated by the palm Raphia taedigera), 
described and commented upon briefly by Anderson & Mori (1967), form the densest, 
most extensive, and permanent of the inundated communities. The yolillales found near 
Puerto Viejo, Boca Tapada, and Cafio Negro appear to have arrived, by way of the large 
rivers (including the San Juan), from the dense stands in the Tortuguero region. 
Some species that, because of their abundance, seem very characteristic of the Lla- 
nuras de San Carlos are Ardisia fimbrillifera, Casimirella ampla, Conceveiba pleioste- 
mona, Connarus costaricensis, Eschweilera costaricensis, Ferdinandusa panamensis, 
Lacunaria panamensis, Macrolobium hartshornii, Pentaclethra macroloba, Potalia 
amara, Quararibea parvifolia, Q. pumila, Sacoglottis trichogyna, Stenanona costari- 
censis, Unonopsis rufescens, Warszewiczia coccinea, Zygia gigantifoliola, and Z. uni- 
foliolata. 
For more information about the characteristics and phytogeographic affinities of 
the flora of La Selva Biological Station, see Gentry (1990), Grayum (1982), Grayum 
& Churchill (1987), Hammel (1986a, 1990), Hammel & Grayum (1982), Hartshorn & 
Hammel (1994), Hartshorn & Peralta (1988), Lieberman et al. (1985, 1996), and Wil- 
bur (1986). 
Caribbean region 
The Caribbean (or Atlantic) region, which is influenced by and more exposed to the sea 
of the same name, is much wetter than the previously discussed region and registers an- 
nual rainfall averages of 50100-6000 mm (Boza & Cevo, 2001). The terrain is quite flat 
here, dotted with few hills over a wide plain, and the soils in general are poorly drained. 
The large network of canals and extensive tracts of swamp forests, the largest in the 
country, are evidence of this. We consider that this is the local source of numerous wet- 
land species found in the previously described northern region, the most obvious ex- 
ample being Raphia taedigera; others, less obvious, include Astrocaryum alatum, 
Campnosperma panamense, Corynostylis arborea, Dalbergia monetaria, Dipteryx 
oleifera, Lonchocarpus cruentus, Malouetia guatemalensis, Poulsenia armata, Prioria 
copaifera, Pterocarpus officinalis, Terminalia bucidoides, and Uncaria tomentosa. 
As previously mentioned, for purposes of the Manual we divide this large region, 
characterized in general by flooded or swamp forests, into two large subregions, dis- 
tinguished by differences in both moisture and details of the composition and structure 
of the vegetation; these are the combined Llanuras de Tortuguero/Santa Clara and the 
Baja Talamanca area. 
Llanuras de Tortuguero/Santa Clara. This subregion shares a large portion of its 
flora with the Llanura de San Carlos. However, although certain important ecosystems, 
