FRAZIER, CHRISTOPHER K.1* and TIMOTHY K. LOWREY2. 1New Mexico Natural Heritage Program, Dept. of Biology, University of New Mexico, Albuquerque, NM, 87131; 2Dept. of Biology, University of New Mexico, Albuquerque, NM, 87131. - Pollination and reproductive ecology of three lowland tropical pitcher plants (Nepenthes).
Tropical pitcher plants, Nepenthes, have been the subject of
substantial scientific scrutiny for their prey digestion, but other
aspects of their biology, particularly their reproductive ecology have
garnered much less attention. I studied the three species of
Nepenthes present in Johore, Malaysia and Singapore, N.
gracilis, N. ampullaria and N. rafflesiana , to
determine if there are significant differences among species in
phenology, floral and nectar characteristics and pollinators.
Differences in flowering period represents at best a partial barrier
to cross-pollination among species. Each species has three flowering
periods between January and July, but the timing of these episodes is
offset among species such that at any given time one, two or all three
species are in flower. Floral presentation differs among species in
such characters as the number of flowers per inflorescence, flower
size and color and sepal shape. N. ampullaria flowers present
pollen during the day, while the other two species open their flowers
in the evening. Nectar is produced nocturnally in all three species,
but they differ in sugar composition and quantity of nectar produced.
These differences suggest the species are adapted to attract different
suites of pollinators. All species are pollinated by moths and small
Diptera, but to differing degrees. N. rafflesiana is
pollinated almost entirely by moths and all of its pollination is
nocturnal. N. gracilis is pollinated almost equally by moths
and small Diptera at night and also by wasps during the night and day.
By day, N. ampullaria flowers have a foul odor and are
pollinated by large flies, wasps and butterflies. The flowers produce
a sweet odor at night and are then visited by moths. These differences
are significant between species, but are still not sufficient to
constitute a complete barrier to cross-pollination.
Key words: carnivorous plants, dioecy, entomophily, Nepenthes, phenology, pollination, vines