P. laheyana grows in rain forests generally above an
altitude of 600m. The leaves of the vine are narrower and generally
shorter than P. praevenosa, the vine mostly sold as the
Birdwing Vine in Southern Queensland and Northern NSW.
Generally the leaves are softer than the lowland vine although
older leaves can be tough. The top surface of the leaves is
quite shiny and has far fewer hairs than P. praevenosa.
Leaves are alternate, and the petiole generally is quite kinked.
The clasp where the petiole connects to the stem almost extends
completely around the stem.
The bark on the older stems or trunks of the vine becomes corky
in appearance. The stems do not reach the thickness of P.
praeveonsa. The thickest I have seen is about 3cm, while
P.praevenosa can grow to the thickness of a man's forearm.
P.laheyana has pipe flowers similar in appearance
to those of P. praevenosa. Pollination is performed
by a small, unidentified fly which appears to become trapped
in the flower over night apparently in its search for a mate.
The seed elongated cylindrical seed capsule forms at the base
of the flower once pollination has occurred. It takes many months
to develop.
A mature seed capsule, light green to yellow in colour, may
contain between 30 and 60 small brown to black heart shaped
seeds.
Ripened seed capsules fall to the ground, where they are found
by scrub turkeys which break them open, consume the flesh and
scatter the seeds. As the turkeys scratch through the litter
on the forest floor, they cover the seeds, virtually planting
them.
This primitive and limited dispersal mechanism is partly responsible
for the slow natural distribution of the vine througout its
range. Once wild viines are removed from their natural habitat,
they are very slow to reproduce and re-colonize these areas.
Furthermore the seed is only viable for a few months.
Compare this to the North Queensland vine, Aristolochia
acuminata, commonly known as Tagala vine. It is the larval
host vine for the Cairns Birdwing Butterfly. In the north, it
is also known as the Birdwing Vine. Unlike Pararistolochias,
Aristolochia seed capsules burst open on the vine. Their
seed is wind dispersed and not reliant on bird distribution.
Hence the Cairns Birdwing and its host vine are not under threat.
Note: Tagala (Aristolochia
acumiinata) is NOT suitable as a host plant for Richmond
Birdwing Butterfly larvae. Eggs of Richmond Birdwing laid on
Tagala vine rarely develop properly.
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