Passiflora lutea | The Italian Collection of Maurizio Vecchia

DESCRIPTION:

It propagates easily from root cuttings, to be taken in the period of quiescence. Stem cuttings or seeds can also be used.

It can be grown outdoors in all Italian climatic zones, except those that are too cold. It must be placed near a fence or, if isolated, must be equipped with light, thin supports. It requires rich, well-drained soil, as it can suffer from root rot in winter if there is excessive waterlogging.

Its flowers are small (up to 1.5 cm in diameter) and yellow-green, not particularly showy. The corona, consisting of two series of filaments, is very light green, almost white. Its spherical fruits, of a violet colour when ripe, do not reach 1 cm in diameter.

P. lutea is a small herbaceous climber native to the United States (Illinois, Pennsylvania, Florida, Texas), with small trilobate leaves. There is sometimes a slight yellow streak along the three main ribs. There are also cultivars with decorative leaves.

I have been growing a specimen in my garden for many years. In winter, it loses its aerial part completely and seems to no longer exist. When spring arrives, it does not hurry to grow, but waits, prudently, for the minimum night temperatures to rise steadily above 10°C. It will then release its first small shoots from the robust, fleshy roots that have remained dormant underground. Worried about this delay, I have sometimes moved the earth to check it has not completely disappeared, but, up till now, I have always found its white roots at a depth of 2-3 cm.

Until now, efforts have been disappointing and P. lutea seems resistant to producing hybrids worthy of interest.

This climber is certainly not cultivated for the beauty of its flowers or any other aesthetic feature. It has, in fact, a rather plain flower, does not produce edible fruit, and its leaves are not particularly striking. However, it is taken into consideration because it is one of the hardiest passionflowers in existence, tolerating winter temperatures down to -15°C. For this reason, many researchers have tried in vain to hybridise it with more beautiful and more delicate species. The hope is that it will be able to transfer its cold resistance genes to other species that cannot be grown where the winter frost is lethal to them.