Manual de Plantas de Costa Rica 107 
pachyphylla, Coccoloba liportizii, Cojoba costaricensis, Cosmibuena valerioi, Den- 
dropanax latilobus, D. querceti, Drymonia turrialvae, Ficus tuerckheimii, Geonoma 
edulis, Guatteria costaricensis, Gymnosporia haberiana, Ilex lamprophylla, I. pallida, 
Macleania insignis, Maianthemum gigas, Meliosma idiopoda, Miconia amplinodis, 
M. tonduzii, Myrsine coriacea, Naucleopsis capirensis, Panopsis costaricensis, Phyllo- 
noma laticuspis, P. tenuidens, Plinia salticola, Podocarpus oleifolius, Prunus annularis, 
Pseudolmedia mollis, Psychotria monteverdensis, Quercus spp., Roupala glaberrima, 
Sanicula liberta, Saurauia montana, Schefflera brenesii, S. rodriguesiana, Schoepfia 
vacciniiflora, Senecio arborescens, S. copeyensis, Sphyrospermum buxifolium, Symbo- 
lanthus calygonus, Symplocos bradei, S. povedae, S. tribracteolata, Talauma glorien- 
sis, Ternstroemia tepezapote, Viburnum costaricanum, Weinmannia pinnata, Wercklea 
insignis, and Zygia palmana. The Continental Divide, where very strong winds in com- 
bination with high precipitation prevail, is home to elfin forests whose characteristic 
species include Ardisia calycosa, A. crassiramea, Freziera forerorum, F. friedrichs- 
thaliana, Gentlea austin-smithii, G. micranthera, Hillia palmana, H. panamensis, 
Roupala loranthoides, and Zanthoxylum melanostictum. 
The Caribbean slope of this cordillera, wetter and more diverse than the Pacific 
slope, harbors some elements from the Pacific slope that occur down to the elevational 
band of (S00—)600—700 m (but in gradually diminishing abundance). However, at these 
middle elevations, the influence of species from the wet lowlands becomes more obvi- 
ous; some taxa clearly evident of this influence are the arborescent palms /riartea del- 
toidea, Socratea exorrhiza, and Welfia regia, as well as Carapa guianensis, Hieronyma 
alchorneoides, Myristicaceae, and Vochysiaceae. 
In general, the Cordillera de Guanacaste is relatively drier and more seasonal than 
the ranges to the south. Perhaps one of the elements that best reflects this is the family 
Rutaceae, which is more diverse in dry to moist forests than in wet forests. Here, the 
Rutaceae reach their highest indices of diversity and abundance in the country, even 
higher than in the contiguous Cordillera de Tilaran, underscoring some of the floristic 
differences between these two ranges. Of the total of 16 genera of Rutaceae known 
from Costa Rica, 75% can be found in the Cordillera de Guanacaste, as well as 60% of 
the 33 total species; Zanthoxylum, the most diverse genus, is represented here by 58% 
of the 12 species known from the country. The species with the highest abundance 
index in this family, some forming almost pure stands, are Peltostigma guatemalense, 
Pilocarpus racemosus, Angostura granulosa, and Amyris balsamifera. The greater sea- 
sonality and dryness of this cordillera compared to the others is also reflected graphi- 
cally by the relatively small area covered by the rain forest life zone (see Tosi, 1969). 
Cordillera de Tilaradn 
The Cordillera de Tilaran is of moderate elevation, rather brief extent, and somewhat 
uniform; its highest points along the Continental Divide lie between 1600 and 1842 m. 
In terms of mountain peaks, it extends in a curve that is more or less convex (viewed from 
