Passiflora poslae | The Italian Collection of Maurizio Vecchia

DESCRIPTION:

This species is currently virtually absent from European collections and is not available from nurseries. I had the opportunity to grow it for a few years, thanks to a cutting obtained from the British National Collection of Passiflora. However, I never saw its flower in my own greenhouse. The only time I was able to admire it was during a Meeting of the Passiflora Society International in England, when we visited the greenhouses of John Vanderplank’s National Collection. There were many plants in excellent condition and Passiflora poslae was flowering at that time.

I remember that, besides the passionflowers, a few other plants attracted the attention of participants. An Aristolochia gigantea was producing large, hanging flowers of a dark colour, rather unsettling, like blood-stained rags. A Monstera deliciosa was full of ripe fruits and we tasted some: the flavour was unusual, halfway between coconut, banana and pineapple.

The official description of Passiflora poslae appeared in 2008 in Curtis’s Botanical Magazine, volume 25, issue 3, August 2008.

Passiflora poslae is recorded as native to Peru according to the Royal Botanic Gardens, Kew database, and it grows primarily in humid tropical biomes. A documented collection in the region crossed by the Madre de Dios river, in the Tambopata area and dating back to 1990, confirms its presence in the rainforests of the south-east of the country. 

The flower recalls Passiflora edulis in its colours and shapes. The corolla is white and the corona, also white, shows a clear and visible pink band in its centre, although thinner and less prominent than in edulis. Passiflora poslae is a species with entire leaves, with an ovate blade and elongated apex. 

Among its most curious details is a truly ingenious defensive strategy. The tips of the leaves bear two small yellow glands that imitate the eggs of butterflies of the genus Heliconius, particularly Heliconius erato. This butterfly lays yellow eggs at the tip of the leaves, exactly where Passiflora poslae prefers that they are not laid. The plant therefore shows the butterfly a “place already occupied”, discouraging it from choosing that leaf for its offspring. 

Cultivation requires conditions similar to those for many tropical passionflowers: a bright environment, well-drained soil and constant humidity. It is advisable to grow it in a pot so that it can be protected during the colder months, as it does not tolerate frost. In open ground it is suitable only in very mild climates.

The ideal substrate is soft, rich in organic matter and mixed with draining materials such as coarse sand or grit, to avoid harmful waterlogging. The exposure may range from full sun to partial shade; in very hot areas it is better to provide some shelter during the central hours of the day. 

During the growing season the soil should be kept slightly moist with regular but never excessive watering. In winter, if grown in a pot, watering should be reduced and the plant placed in a protected environment, with temperatures above 12 to 15 degrees Celsius.

Fertilisation can be carried out with balanced fertilisers at regular intervals during the growing period, supporting both vegetative development and flower production. A light pruning after flowering helps to contain the size of vigorous plants and to stimulate the formation of new shoots. 

Propagation is preferable by semi-woody cuttings in a warm and humid environment, faster and more reliable than seed, which generally requires longer times.