Manual de Plantas de Costa Rica 185 
the period 1940-1960, making a characterization of the original forest difficult. Popu- 
lations of numerous important taxa, some of them endemic, suffered a major fragmen- 
tation of their natural distribution ranges. Notable examples include the palms 
Cryosophila guagara, whose only protected populations are found in Carara, Corcov- 
ado, and Piedras Blancas National Parks, and Bactris militaris subsp. militaris, en- 
demic to this valley, with only a very small, unprotected, and very endangered popula- 
tion remaining. Information from Allen (1956) indicates that both used to be quite 
common in the region. 
Systematic and relatively intensive explorations of the flora of the Osa Peninsula 
are fairly recent, although it was botanized as early as 1890 (see the History chapter for 
more details). It was Paul Allen (1956) who began the detailed documentation of the 
rich flora of the Golfo Dulce region, with his accounting of 433 species of trees repre- 
senting 267 genera and 72 families, mainly from the Esquinas region (today Piedras 
Blancas National Park) and near Palmar Norte. During and since the years 1985-1989, 
continued exploration has better documented the rich flora of this important area. Cur- 
rently, according to the INBio database (ATTA, Nov. 2003), at least 2571 species of 
seed plants and 289 species of ferns and fern allies are known from the region (Osa 
Conservation Area). Some characteristic elements of this region (especially those of the 
tropical wet forest life zone) of South American origin, many discovered during recent 
efforts, are: Anthodiscus chocoensis, Aspidosperma myristicifolium, Beilschmiedia 
curviramea, Byttneria pescapraeifolia, Buchenavia tetraphylla, Calophyllum longi- 
folium, Caryocar costaricense, Chaunochiton kappleri, Chromolucuma_rubriflora, 
Combretum assimile, Couepia platycalyx, Couratari guianensis, C. scottmorii, Cremas- 
tosperma sp., Dalbergia frutescens, Dendrobangia boliviana, Discophora guianensis, 
Doliocarpus hispidus, Elaeoluma glabrescens, Elvasia elvasioides, Eschweilera integri- 
folia, Gouania colombiana, Gustavia brachycarpa, Hirtella tubiflora, Homalomena ery- 
thropus, Humiriastrum diguense, Inga cylindrica, Micropholis venulosa, Naucleopsis 
ulei, Oenocarpus mapora, Pradosia atroviolacea, Parabignonia steyermarkii, Para- 
machaerium gruberi, Parkia pendula, Paullinia tenuifolia, Persea pseudofasciculata, 
Pitcairnia quesnelioides, Pterygota excelsa, Qualea paraensis, Sagotia brachysepala, 
Sloanea brachytepala, Sphyrospermum ellipticum, Styrax glabratus, Uribea tama- 
rindoides, and Vochysia megalophylla. Some other species are disjunct from the north 
(Mexico—Nicaragua), e.g., Chamaedorea geonomiformis, Connarus lentiginosus, Gym- 
nanthes riparia, Oecopetalum greenmanii, Philodendron popenoei, Recchia simplicifo- 
lia, Reinhardtia latisecta, Sloanea longipes, S. petenensis, and Zygia cognata; some are 
shared immediately to the south with Panama, e.g., Alchornea grandis, Fusispermum 
laxiflorum, Oxandra longipetala, Philodendron burgeri, Pleurothyrium hexaglandulo- 
sum, and Tragia correae; and a few taxa are shared with the Antilles, e.g., Chrysophyl- 
lum oliviforme, Freziera grisebachii, Pleodendron, and Ziziphus chloroxylon. 
All of this is evidence that the Osa Peninsula is one of the richest areas in plant di- 
versity all along the Pacific coast, and even in the country. Plot studies have registered 
