plant material. They usually lack chlorophyll and do
not photosynthesize. The Burmanniaceae are terres-
trial saprophytes related to the Orchidaceae. They
lack chlorophyll and have thin stems with spiraled,
scale-like leaves. Gymnosiphon suaveolensha.sa.weak,
4-8-cm stem with one to several flowers at its tip; both
the flower and stem are lavender-white. Usually grow-
ing in small groups, it is widespread, though uncom-
mon in Monteverde. Apteria aphylla is a similar but
much less common herb found in the Penas Blancas
valley (800-900 m). The highly reduced gentian
Voyria flavescens (Gentianaceae) is a solitary, 7-10-
cm herb with a yellow stem and flower. Lacking chlo-
rophyll, with its leaves reduced to scales, this deli-
cate herb superficially resembles Gymnosiphon. This
rare mycotrophic species has only been collected in
the understory of secondary forest in the Monteverde
community (1300-1400 m). A similarly shaped mono-
cot, Triuris sp. (Triuridaceae), is known from Monte-
verde from a single individual collected in the elfin
forest (Davidse et al. 1994).
Stranglers. Stranglers begin life as epiphytes. As they
increase in size, they send down adventitious roots
that coalesce into a network enclosing the trunk of the
host tree. The strangler's crown overtops the crown
of its host. The combination of shading, competition
for nutrients and, possibly, a girdling effect of the fig
roots encircling the host's trunk kills the host. Once
the host tree is dead, the strangler can persist for de-
cades as a free-standing tree (Fig. 3.16).
Species of Ficus are the best-known Stranglers, and
several species are common at Monteverde (see Burger
1977 for a key to species). Germination experiments
with the seeds of F. pertusa and F. tuerckheimii un-
der simulated epiphytic and terrestrial conditions
showed that Ficus seeds rarely germinate in soil, but
show no autopathic effects (Titus et al. 1990; see Titus,
"Why Strangler Figs," p. 71). Evidence for a specific
host preference in F. crassiuscula was documented by
long-term observations (Daniels and Lawton 1991,
1993). The independent evolution of the strangling
habit in F. crassiuscula, a member of the usually free-
standing subgenus Pharmacosycea, was discussed by
Lawton (1986, 1989) and Ramirez (1988).
Ficus crassiuscula, a common tree in the cloud
forest known locally as chilamate, is not a true hemi-
epiphytic strangler. It begins life as a vine, snaking
through the understory in search of an appropriate
host tree to climb. The vines show a preference for
Guarea kunthiana, a canopy tree common in the cloud
forest (Lawton 1986,1989, Daniels and Lawton 1991,
1993). Four species of Ficus found on the upper Pa-
cific slope between 1200 m and the Continental Di-
vide are true Stranglers of the subgenus Urostigma.
Ficus hartwegii grows to be a huge canopy tree inFigure 3.16. View upward into the hollow trunk of a strangler fig, Ficus tuerckheimii (Moraceae) after
the trunk of the host tree has died and rotted away. Photograph by Gregory Dimijian.59 Plants and Vegetation