Manual de Plantas de Costa Rica 101 
pally at the mouths of the Rios Colorado (Barra del Colorado), Tortuguero, Moin, and 
Gandoca. Little is known about the characteristics of these mangroves, but apparently 
they are structurally more developed than those of the western coast (Pool et al., en 
Gomez P., 1986). Perhaps one of the best studied mangroves is the one at the mouth of 
the Rio Moin, which Jiménez (1981) found to be dominated by Avicennia germinans, 
Laguncularia racemosa, Pterocarpus officinalis, Rhizophora mangle, and R. racemosa, 
species that also dominate the Pacific mangroves. One of the differences between man- 
groves of the two coasts is the lack of such species as Avicennia bicolor, Mora oleifera, 
Muellera frutescens, Pelliciera rhizophorae, and Tabebuia palustris in those of the 
Caribbean (although Pelliciera is to be expected in the mangroves of Barra del Colorado, 
given that it is known from the Caribbean coast of Nicaragua; N. Zamora V., pers. obs.). 
The beach vegetation of Costa Rica also varies between the Caribbean and Pacific 
coasts, with several conspicuous elements shared, such as Caesalpinia bonduc, Cana- 
valia rosea, Coccoloba uvifera, Ipomoea pes-caprae, and Talipariti tiliaceum, but the 
most obvious and characteristic species of both is the coconut palm (Cocos nucifera). 
Perhaps due to the very long dry season along the northernmost Pacific coast, the north- 
ern limit of natural distribution of this last species appears to lie in the neighborhood of 
Bahia Culebra, in Guanacaste. There has always been much controversy about the ori- 
gin and natural distribution of the coconut. Even though Wercklé (1909: 54) emphati- 
cally declared that “There is so much evidence of the American origin of the coconut 
that there is no reason for doubt,” Sauer (1983) provided clear arguments that the co- 
conut originated in the region of the Indian Ocean. Sauer also pointed out that the com- 
mon races on the Caribbean and Pacific coast of Costa Rica arrived from opposite di- 
rections and are very different from each other. 
Costa Rica’s islands, taken together, account for only 120 km?. The two largest is- 
lands (Herrera, 1985) are Chira (43 km7), in the Gulf of Nicoya, and Cocos (24 km7?). 
Except for Cocos Island, the Pacific islands (Chira, San Lucas, San José, Guayabo, del 
Cafio, and Violin, among the largest of the inshore islands) all have floras derived from 
the prevailing continental flora at the same latitude. Because it is so far offshore (548 
km), Cocos Island has a different and somewhat unique flora; its irregular topography, 
with elevations from 0 to 634 m, and heavy rainfall, which varies between 5000 and 
7000 mm (Herrera, 1985), contribute to a relatively diverse cover of premontane rain 
forest (Tosi, 1969). According to data gathered from herbaria and databases, we estimate 
that the total vascular flora of the island has some 200—250 species, of which several are 
endemic, including Cecropia pittieri, Chloris paniculata, Epidendrum cocoénse, E. in- 
sulanum, E. jimenezii, Eugenia pacifica, Hoffmannia nesiota, H. piratarum, Kyllinga 
nudiceps, Marcgravia waferi, Psychotria cocosensis, Sacoglottis holdridgei, and pteri- 
dophytes such as Asplenium barclayanum, Cyathea alfonsiana, C. nesiotica, C. notabilis, 
Elaphoglossum cocosense, E. incognitum, E. reptans, Huperzia brachiata, H. pittieri, 
Hymenophyllum cocosense, Hypolepis lellingeri, and Thelypteris cocos (the Cyathea 
spp. being tree ferns). The INBio database (ATTA) accounts for a total of 207 species 
