Passiflora caerulea (Blue Passionflower)

Scientific name

Passiflora caeruleaL.

Synonyms

Passiflora caerulea Lour.; Passiflora caerulea var. angustifolia G.Don; Passiflora caerulea var. glauca Mast.; Passiflora caerulea var. glaucophylla Loudon; Passiflora caerulea var. imbricata Mast.; Passiflora caerulea var. regnelliiMast.

Common names

Blue passionflower

Family

Passifloraceae

Origin

Passiflora caerulea is native to southern Brazil and Argentina

Naturalised distribution (global)

Locations within which Passiflora caerulea is naturalised include New Zealand and several oceanic islands in the Pacific Ocean.

Introduced, naturalised or invasive in East Africa

Passiflora caerulea has been documented in parts of East Africa, particularly in parts of Central and Nairobi Provinces of Kenya.

Habitat

Passiflora caerulea is found on margins of forests and gaps and in riparian zones (banks of watercourses).

Description

Passiflora caerulea  is a woody climber growing up to 25 m high, depending on supporting tree height.

The stems of P. caerulea  are very short. Leaves are palmately 5-lobed (sometimes 3 or 7 lobes),10-18 cm long and wide. The base of each leaf has a  twining tendril 5-10 cm long, which helps to support the plant by twining on the supporting plant.

Flowers of P. caerulea are about 10cm diameter with 5 sepals and petals that are similar in appearance. 5 greenish-yellow stamens and 3 purple stigmas.

The fruit is an orange-yellow berry 6 cm long by 4 cm diameter, containing many seeds.

Reproduction and dispersal

Flowers of Passiflora caerulea are generally not self-fertile, and will need other blue passionflower vines in close proximity to be cross-pollinated. Seeds are dispersed by mammals and birds. It also spreads through cuttings.

Economic and other uses

Passiflora caerulea is a popular ornamental plant. Its fruit is edible but is not highly valued. These uses cannot compensate for this plant's overall negative impacts.

Environmental and other impacts

Wild plants can smother trees and shrubs and can naturalise in disturbed forests, along river banks, fencerows, abandoned farms, and urban open spaces. Passiflora caerulea has been listed as a noxious weed in South Africa(prohibited plants that must be controlled. They serve no economic purpose and possess characteristics that are harmful to humans, animals or the environment).

Management

The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species. Some components of an integrated management approach are introduced below.

The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.

Small plants can be hand-pulled. Larger plants can be treated chemically by cutting the stem close to ground level and treating the stump. Spraying whole plants is problematic as it can affect the host plants. When using any herbicide always read the label first and follow all instructions and safety requirements. If in doubt consult an expert.

Biological control agents have been developed for related species of Passiflora.

Legislation

Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.

Notes

There are varieties, like Passiflora caerulea 'Constance Eliott', that have pure white fragrant flowers. In tropical climates, P. caerulea will bloom throughout the year.

References

Henderson, L. (2001).  Alien weeds and invasive plants. A complete guide to declared weeds and invaders in South Africa.  Plant Protection Research Institute Handbook No. 12, 300pp. PPR, ARC South Africa.

Pacific Island Ecosystems at Risk (PIER). Passiflora caerulea L., Passifloraceae: plant threats to Pacific ecosystems. www.hear.org/pier/species/passiflora_caerulea.htm. Institute of Pacific Islands Forestry, Hawaii, USA. Accessed March 2011.

Editors

Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.

Acknowledgments

This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).

Contact

BioNET-EAFRINET Regional Coordinator: eafrinet@africaonline.co.ke