or tissue culture using aesthetically superior clones
as parent stock. Monteverde would provide the ideal
climate for production of many orchids. Although
some species clearly require undisturbed habitats,
others are locally weedy on disturbed roadsides, in-
cluding Habenaria monorrhiza, H. floribunda, Epi-
dendrum radicans, and numerous Elleanthus. These
species, which naturally occur along landslides or
areas that are occasionally burned, benefit from patchy
human disturbances.
Endemism among orchids of Monteverde appears
to be low. Ten species are known only from Monte-
verde, but these are mostly minute and easily over-
looked. Of these minute orchids, five species of Stelli-
labium have been discovered, three of them originating
from a single branch fall. One of the five species, S,
barbozae, was discovered in 1995 growing at the In-
formation Center of the MCFP in public view. The
yellow-flowered Maxillaria haberi is known only
from the lower Penas Blancas Valley and one site on
the Atlantic slope of Volcan Barva.
As at La Selva (Atwood 1988), the largest three or-
chid genera at Monteverde are Epidendrum, Maxillaria,
and Pleurothallis, comprising 37% of the orchid flora
(Appendix 3). No large orchid genus is as well studied
as Maxillaria in Costa Rica (106 spp.). If the number of
Maxillaria species is representative of the orchids as a
whole, the total number of orchid species in Monteverde
could exceed 600. The patchy and lofty distribution of
orchids makes documentation a long process.Acknowledgments I thank William Haber for his
logistic help, access to his continually revised species
database, and general encouragement in field efforts,
and Robert Dressier for discussions with the species
list. I thank Steve Ingrarn and Karen Ferrell-Ingram
for collecting Costa Rican orchids, and Dora Emilia
Mora de Retana for identifications of species of
Oncidiinae and persistence in obtaining permits. This
material is based on work supported by the National
Science Foundation and by the Office of Forestry,
Environment and Natural Resources, Bureau of Sci-
ence and Technology, of the U.S. Agency for Interna-
tional Development under NSF Grant DEB-9200812.EVOLUTION IN CLOUD FOREST PSYCHOTRIA SECTION
NOTOPLEURA VIA GROWTH FORM DIVERSIFICATION
Molly Nepokroeff & Kenneth J, Sytsmahe epiphytic growth form has evolved inde-
pendently in at least 80 families of vascular
plants (Kress 1989; see Ingram, "Epiphytes,"
pp. 72-73). Their growth form evolution has been
little studied in cloud forests. The evolution of epiphy-
tism from terrestrial ancestors has been documented
in Columnea (Gesneriaceae; Smith and Sytsma 1994)
and has been suggested for woody gentians (Sytsma
1987). However, the evolution of epiphytism has most
likely occurred via many different evolutionary path-
ways, even within families and genera (Benzing 1989).
The genus Psychotria (Rubiaceae) is one of the larg-
est genera of flowering plants, with 1250—1600 species
worldwide (Hamilton 1980). Appendix 1 lists three
species of epiphytic Psychotria (Rubiaceae), a genus
of mostly understory shrubs. In growth form, most
Psychotria are branched understory shrubs. Others are
epiphytes, tuberous myrmecophiles (ant-inhabited
plants), lianas, and succulent, single-branched forms
(Sohmer 1988). In Monteverde, many species of Psy-
chotria occur sympatrically. Due to its large number
of species, the genus serves as a model system to un-
derstand speciation patterns in the tropics.Phylogenetic systematles provides the historical
framework for understanding processes of evolution
and adaptive radiation (O'Hara 1988). A promising
technique to study the adaptive radiation of a lineage
is to superimpose the characters of interest onto a
well-supported phylogeny (Harvey and Pagel 1991).
A molecular phylogeny derived independently from
morphological characters avoids the bias inherent in
analyzing evolutionary events based on the charac-
ters under examination (Givnish et al. 1994).
One natural group, Psychotria section Notopleura
Bentham, is represented in the MCFP by seven species.
Members of section Notopleura are characterized by
succulent, unbranched, terrestrial habit or branched,
epiphytic growth form, a single dorsal median ridge on
the seeds, and a single inflorescence in each leaf axil.
Psychotria section Notopleura is well differentiated
from other members of the genus Psychotria, and mo-
lecular evidence suggests that it may hold a basal po-
sition in the genus or may be considered a separate
genus (Nepokroeff and Sytsma 1996).
A recent phylogeny, based on independent mo-
lecular characters (ribosomal DMA sequence data;75 Plants and VegetationT