Little is known about non-mycorrhizal endophytic fungi in tropical
orchids; still less is known about how endophytes vary within and
between individual orchid plants. Fungal endophytes were isolated from
roots and leaves of epiphytic and lithophytic orchids in the genus
Lepanthes; seven species, from rainforests in Puerto Rico,
were sampled. The endophytes observed most frequently were
Xylaria species and Rhizoctonia-like fungi, found in
29% of roots and 19% of leaves, and 45% of roots and 31% of leaves,
respectively. Five deuteromycete genera were also isolated, occurring
in 19% of roots and 43% of leaves (combined). At least nine species of
Xylaria were found, with several species sometimes occurring
in a single plant. Differences between roots and leaves in frequency of
Xylaria and Rhizoctonia isolates were not
significant, although differences among orchid species in number and
types of endophytes were. Heterogeneity of endophytes in single plants
and plant organs was greater than differences between species. Many
Lepanthes species are very restricted in distribution, and
knowledge of their interactions with endophytes might be useful in
species management.