of epiphytes and ferns in Monteverde and La Selva
than at the other sites, although this is in part due to
more thorough collecting of these life forms in Costa
Rica (Gentry 1985,1990, 1993). A notable difference
among sites is the high proportion of trees and low
representation of herbs in the flora of the Manaus site
compared with the other sites (Prance 1990). In terms
of tree species density (number of species per hect-
are), the Amazonian sites are much higher than the
others (Gentry 1990, Prance 1990). The Altantic slope
plots at Monteverde are comparable to lowland sites
in species density (Gentry 1990, Nadkarni et al. 1995;
see Table 3.6).
The cloud forest at Monteverde is also distinct from
the high cloud forest of the Cordillera de Talamanca
in southern Costa Rica. Most of the latter forest be-
longs to a life zone not found in Monteverde, the mon-
tane rain forest (which lies mostly above 2400 m) and
to the upper elevational limits of lower montane rain
forest (extending to 2400 m). Many of the tree species
characteristic of the highest peaks at Monteverde are
more typical of cloud forests in the Talamancas (e.g.,
Alfaroa costaricensis, Billia hippocastanum, Brunel-
lia costaricensis, Ilex vulcanicola, Ocotea pittieri, O.
viridiflora, Quercus corrugata, Weinmannia pinnata)
(Kappelle et al. 1990, Kappelle 1995, Kappelle and
Leal 1996). In South American cloud forest, most of
the genera are the same as those in Costa Rica, but
nearly all the species are different (Kelly et al. 1994).
The diversity of these montane cloud forests is gen-
erally lower than that of the lower montane life zone
(Kelly et al. 1994, Kappelle 1995).
Much of the flora of the seasonal moist and dry
forest on the Pacific slope extends from northwestern
Costa Rica to southern Mexico (Hartshorn 1983,
Janzen 1983). Excluding grasses (Poaceae), the flora
of Santa Rosa National Park totals 603 species (Janzen
and Liesner 1980), or about one-fifth as many species
as at Monteverde, which demonstrates the compara-
tively low diversity of seasonally dry habitats in Costa
Rica. In the same study, the whole of lowland
Guanacaste Province listed only 992 species, com-
pared with 3021 at Monteverde. The only notable af-
finity between the floras of Monteverde and Santa
Rosa National Park occurs on Pacific slope below 1200
m. A total of 75 species of trees and treelets occur in
both Monteverde and Santa Rosa; almost all of these
are from the dry Pacific slope. Only 11 species of trees
known from Santa Rosa reach the Monteverde com-
munity above 1200 m, and of these, only Trema
micrantha (a weedy light gap colonist) and Topobea
brenesii (a hemiepiphyte) reach the cloud forest
above 1500 m (Janzen and Liesner 1980, Hartshorn
and Poveda 1983, Haber 1991; Appendix 1).
Santa Rosa supports 17 species of orchids com-
pared to more than 500 at Monteverde, with only one
species (Polystachya masayensis) in common be-
tween the two sites. The largest family at Santa Rosa,
Fabaceae, has 125 species compared to 117 at Monte-
verde, of which only 10 species reach the cloud for-
est. Santa Rosa has 30 species of ferns and fern allies
compared to 358 at Monteverde. Conspicuous differ-
ences in the tree composition of the two sites are the
prominence of Fabaceae and Bignoniaceae in the dry
lowlands; those families are essentially replaced by
Lauraceae, Meliaceae, and Myrtaceae in the cloud
forest. Inga, with eight species occurring above 1200
m at Monteverde, is the only genus of Fabaceae well
represented in the montane flora (see Koptur, "Breed-
ing Systems," pp. 85-87).
In contrast, the flora of the Atlantic slope has a
much stronger relationship with the lowland wet for-
est habitat of La Selva and the similar forests of South
America (Croat 1978, Gentry 1983, 1985, 1993, Hart-
shorn and Hammel 1994). For example, 23% of the
114 species of orchids at La Selva also occur in Monte-
verde (Atwood 1987; Appendix 3). Both areas are
rich in Lauraceae, Rubiaceae, Melastomataceae, and
Piperaceae, and both display highly diverse epiphyte
communities. La Selva's fern and epiphyte floras ap-
pear to be generally more abundant and diverse than
at sites in similar life zones in South America (Gentry
1990, Hammel 1990, Hartshorn and Hammel 1994).
Epiphytes and ferns of Costa Rica's Atlantic slope are
favored by the northeast trade winds, which bring
moisture from the ocean during the dry season, and
by the cooling influence of cold air drainage down the
mountain slope at night at La Selva. In contrast, some
tree taxa (e.g., Moraceae and Sapotaceae) are much
less prominent in both the premontane and lower
montane life zone belts at Monteverde than in the
lowland wet forest sites (Gentry 1990, Hartshorn and
Hammel 1994).
Several species of Atlantic slope plants (e.g.,
Ticodendron incognitum, Ticodendraceae) indicate a
relationship between Monteverde's flora and the Cen-
tral American flora to the north. A very rare tree on the
Atlantic slope of the Tilaran mountains at 700 m,
Deherainia spec. nov. (Theophrastaceae), has its only
known relatives in Mexico, Guatemala, and Cuba. Simi-
larly, Decazyx macrophyllus (Rutaceae) was known
only from Nicaragua to Mexico previous to the
Monteverde Flora Project (Haber 1991). Another rare
tree, Caryodendron angustifolium (Euphorbiaceae),
collected on the Atlantic slope and at La Selva, is the
northernmost extension of this South American genus.
The vegetation of the cloud forest in Monteverde has
mixed origins, with clear affinities both to the cloud
forests of northern Central America (e.g., Quercus spe-
cies extending north to Mexico) and to South America68 Plants and Vegetation