TRAP TYPE: Pitfall Trap
Currently six listed species occupying mountain plateaus of the Guiana
Shield in north-central South America (Venezuela and bordering Brazil
Heliamphora is one of three genera of the family Sarraceniaceae
(the others are Darlingtonia and Sarracenia). One interesting
fact about Heliamphora is the area where it grows: the flat-topped
mountains (called "tepuis") of what is collectively called the Guiana
Highlands. These mountains, which average about 2400 m tall, rise rather
sharply to flat summit areas that are often cloud covered. Heliamphora
can be found in wet, boggy areas of the tepuis. This picture shows Heliamphora
minor on Chimanta-Tepui.
There are six species of Heliamphora on the tepuis. Five of the species,
like H. minor (shown), tend to have short stems, but one, H.
tatei, tends to climb or lean on other plants and reaches 4 m in
height. According to DNA data, Heliamphora is most like the ancestor
of the family Sarraceniaceae. The flowers are recurved, as in Darlingtonia
and Sarracenia. Recurved flowers have been claimed to be an adaptation
for keeping rain from collecting in flowers, and thus pollination could
occur even during rainy periods.
The leaves of Heliamphora are reportedly not very efficient
at catching insects, judging from the quantity of insects found at the
bottom of the tubular leaves ("pitchers"). The leaves of H. heterodoxa,
shown here, show several distinct regions. The small hoodlike "spoon"
at the tip of a leaf has nectar glands on its lower surface. The reddish
color of the spoon may attract insects, and the hoodlike shape might prevent
nectar from being washed away by rain--these are only guesses. The funnel-like
zone of the leaf below the spoon tends to be reddish and therefore an
insect might follow that color cue. The lower necklike part of the funnel
has downwardly-pointing hairs that insure that an insect will continue
to walk downward, since walking upward against these tiny spikes would
be difficult. The lower part of the leaf, a little wider than the base
of the funnel, contains water with a digestive enzyme, a pool from which
an insect, once caught, rarely escapes. The leaf seems like a well-designed
trap. If the number of insects caught is fewer than in leaves of Darlingtonia
and Sarracenia, perhaps that reflects a relatively low insect
density in the relatively high elevations of the tepuis.
The sepals of Heliamphora heterodoxa are easily seen and vary
from green to red in color--the petals are small and can't be seen in
this picture. The flowers tend to become upright as the fruits mature.
The fruits of Heliamphora are dry when they mature, and split
open at the sides to reveal numerous seeds--botanists call such fruits
capsules. The seeds probably shake out through the slits in the capsule.
A stronger wind would shake out more seeds, which would be advantageous
in carrying a higher proportion of the seeds for longer distances.
The seeds of Heliamphora, seen much magnified here, have wings
on them. This suggests that they are dispersed by wind. The wings probably
permit the seeds to be picked up by gusts of wind, once they have fallen
to the ground. However, wings of this sort aren't efficient at dispersal
for long distances in wind--a few seeds would be carried long distances
in major storms, but in most weather conditions, many seeds would fall
near the parent plant. This may be a good dispersal strategy, because
the tepuis are like relatively small islands, so most of the habitats
where Heliamphora could grow are very close to the existing plants.
Heliamphora does not grow in the lowland areas surrounding the
tepuis--the climate and other conditions are just too different from the
temperature and moisture on the top of these tableland mountains.
Ca. 6 Listed Species
H. nutans Bentham (1840) | H.
tatei Gleason (1931) | H. tyleri
Gleason (1931) | H. minor Gleason
(1939) | H. heterodoxa Steyermark
(1951) | H. ionasii Maguire (1978)
| H. hispida Wistuba & Nerz
(2000) | H. folliculata Wistuba,
Harbarth & Carow (2001) |
H. chimantensis Wistuba, Carow & Harbarth (2002)
| H. elongata Nerz (2004) |
H. pulchella Wistuba, Carow, Harbarth & Nerz (2005)
| H. sarracenioides Carow, Wistuba & Harbarth (2005)