Manual de Plantas de Costa Rica 135 
by the palm Raphia taedigera; marillales, dominated by Calophyllum brasiliense; and 
a few forests (known as camibar forests) dominated by Copaifera aromatica. Other lo- 
cally dominant elements include Acacia ruddiae, Astrocaryum alatum, Carapa guia- 
nensis, Elaeis oleifera, Ficus insipida, Grias cauliflora, Lonchocarpus cruentus, Lue- 
hea seemannii, Prioria copaifera, Pterocarpus officinalis, and Symphonia globulifera. 
Colonies of Calathea crotalifera, C. lutea, Heliconia latispatha, Spathiphyllum 
friedrichsthalii, and S. laeve are also frequent. 
Generally speaking, the vegetation patterns of this subregion have quite a bit in 
common with those along the northern Caribbean coast of Nicaragua (Vandermeer et 
al., 1990; Granzow-de la Cerda et al., 1997) and with the broadleaved forests of the 
Honduran and Nicaraguan Mosquitia (Zamora V., 2000). 
A phytogeographic analysis of the flora of Nicaragua (Stevens, 2001) showed the 
Caribbean zone to have more species with distributions ranging to the south than to the 
north. One might consider this a generalized north-south Caribbean Mesoamerican pat- 
tern, with some elements, e.g., Dioclea rosea, Inga laurina, and Miconia tomentosa, 
known in Costa Rica only from this zone. Standley (1937b), Hartshorn (1983) and the 
references below (at the end of the discussion about the Llanura de San Carlos) also 
mentioned this pattern for Costa Rica and various regions therein. The pattern evident 
in this region is closely related to the Yucatan-Petén vegetation as designated by Gdmez 
P. (1982, 1986). Gémez indicated the southern boundary of said vegetation pattern to 
be more or less defined by the southern limit of naturally occurring pines in Nicaragua. 
However, a number of its species—such as Acoelorraphe wrightii, Christiana afri- 
cana, Hirtella guatemalensis, and Zygia conzattii—reach the northern zone of the Lla- 
nura de Los Guatusos in Costa Rica. Some others, such as Angostura granulosa and the 
palm Reinhardtia latisecta, occur as high as 5}00—600 m elevation near Estacion Pitilla 
in Guanacaste National Park. 
Llanura de San Carlos. As one moves northeastward, a gradual change in vegeta- 
tion is apparent, as mentioned previously, tending toward greater diversity concomitant 
with different seasonality. Close to the mountains, at the base of the Cordillera Central, 
there are no dry months, whereas in the northern section of the Llanura de San Carlos 
one or two months per year are dry. Also, the combination of flat, low (less than 100 
m) topography interspersed with hills contributes to a change in vegetation. Generally, 
this subregion is characterized by a climate that is more humid and less seasonal than 
the previous, and most of the area falls into the category of tropical wet forest. Long- 
term studies of precipitation at the nearby La Selva Biological Station revealed an 
annual average of 3962 mm (Sanford et al., 1994); this high rainfall prevents the entry 
of a large number of species from the much drier Llanura de Los Guatusos. The north- 
ern part of this plain, bordering on the Rio San Juan—where the topography is more 
irregular, drainage is generally better and seasonality is predictable—is a region of 
very high plant diversity, with up to 131 species and 639 individuals (> 10 cm DBH) in 
