Thursday, January 5, 2012

Golden Passionflower

Passiflora aurantia var. pubescens

I was mystified when my companions and I found this flower, while walking (on private property) at the Bunya Mountains.

Its leaves looked like those of the familiar red passionflower, Passiflora aurantia var. aurantia, (below), which grows at Picnic point and various other places around Toowoomba, but the flowers were very different.

In the photo above you can see that the petals and sepals of the flowers of the familiar plant, which age from white to red, are always concolorous (a word which means that the back is the same colour as the front.)

Both plants have five rather small petals, and five larger sepals - brightly coloured ones which look like petals.
In our mystery plant, the sepals are discolorous. Their backs backs age from the pale yellow of this bud, to a stronger shade of yellow, always with a hint of green.

The front of the sepals, on the other hand, brightened - as did the little petals - from greenish white...

to deep orange.

The little ring of filaments, the “crown of thorns” in the centre of the flower, was very eye-catching in all stages - a gleaming fluoro orange, quite different from the soft pinkish red of the more familiar variety of Passiflora aurantia.

To our delight, a little research revealed that what we had was indeed P. aurantia - but a rare variety of it. It is P. aurantia var. pubescens, as opposed to the familiar P. aurantia var. aurantia.

The reference book which helped us distinguish between the two(Stanley and Ross. “Flora of South-eastern Queensland”) doesn’t mention the conspicuous differences between the flowers, but focuses instead on the “hairiness” of var. pubescens. (“Pubescent” is a botanical term meaning “hairy”.)

In practice, we needed a good magnifying glass to find the almost-invisible little hairs on the leaves and on the ovary.
(The ovary is that ovoid bit that’s going to turn into the fruit. To see it enlarged, click on the photo.)

Compare these two flowers, and you can indeed see that our golden passionflower's ovary is indeed softly hairy, while the red passionflower's is smooth.

It would be interesting to compare the mature fruits.

Meanwhile, another difference that we noticed was our inability to find any hint of the little glands on the leaf petiole of var. pubescens.
P. aurantia var. aurantia
has a tiny, but easily found pair of them, just near the base of the leaf.
Something had been nibbling the leaves of our golden passionflower vine. Perhaps it was the caterpillars of glasswing butterflies, who may find it is just as good a host as its red-flowering relative. Like that plant, this light vine is something we would love to have in our garden.

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