PASSIFLORA
Geo Coppens d'Eeckenbrugge (January 2001)
List of species
 


With more than 450 species, Passiflora is the most important genus of the family Passifloraceae. It is further divided into 24 subgenera (Killip, 1938; Escobar, 1988,1989). Most of the species producing an edible fruit belong to the subgenera Passiflora and Tacsonia. Many species present ornamental interest because of the unique and spectacular flowers, or are used for their sedative, antispasmodic, antibacterial, and insect-resistant properties (Coppens d’Eeckenbrugge et al., 1997).

General morphology

Passiflora species are generally perennial herbaceous or woody wines with alternate leaves, a pair of stipules and a tendril at each node, flowers solitary or in pairs (rarely in inflorescences). The flowers are very characteristic with their corona, their androgynophore bearing the ovary, three stigmas and five anthers well above the corolla. The floral cup is prolonged by a floral tube, both forming the hypanthium. An operculum and a limen close the nectar chamber. Despite this high number of very particular traits, Passiflora species show an impressive morphological variation at all the levels of their classification.

Taxonomy

The subgenus Passiflora is further divided into sections (Table 1). The most interesting are the Incarnatae (including the common maracuja, P. edulis), Tiliaefoliae (including the sweet granadilla, P. ligularis), Quadrangulares (including the barbadine, P. quadrangularis, and the sweet maracuja, P. alata), and Laurifoliae (including the bell apple, P. laurifolia, the granadilla de Quijos, P. popenovii, and a number of very interesting forest species).

The Andean subgenus Tacsonia, which includes the banana passion fruits, has also been divided into sections. However, this grouping is less clear and we shall not mention it in the description of species.

Table 1. Subgeneric classification of some edible passion fruit species 
(in order of economic importance)

Economic importance

Statistics on production of passion fruits are scant and incomplete. The most important species is maracuja, and more particularly yellow maracuja (P. edulis f. flavicarpa). Brazil is by far the largest producer with more than 300,000 t, of which more than 50% is processed into juice for the domestic market. Other significant producers are Colombia, Ecuador, Peru, and Indonesia with a few tens of thousand tons each.

Only producer countries have significant fresh fruit markets. The international exchanges essentially consist of 10,000 to 15,000 tons of concentrate at 50°Brix (about 10 tons of fruit are required for 1 ton of concentrate). Europe is the leading importer, with 60-70% of the exported product, versus 20-22% for the USA.

Other species are commonly found on South American national markets, the sweet granadilla and the banana passion fruit (P. tripartita var. mollissima) in the Andean countries, the barbadine in tropical lowlands. The cultivation of sweet maracuja is developing rapidly in southern Brazil. The great majority of Passiflora species are home garden products and their commercialization is anecdotal.

Commercial production of passion fruits is recent. It started in the 1950's for the maracuja, in Hawaii and Australia, and the banana passion fruit and sweet granadilla in the Andes of Colombia.

 Reproductive biology

This figure shows the characteristic elements of passion flowers. The floral tube is particularly long in the subgenus Tacsonia. The number of sepals and petals may be three, five or eight. The ovary and five stamens are borne on an androgynophore. The unilocular and tricarpelar ovary is surmounted by three styles. The fruits are usually globular or oval berries. The edible part is constituted of the juicy or mucilaginous pulp contained in the arils surrounding the seeds.

The species of subgenus Passiflora are generally pollinated by insects, mostly big bees of the genus Xylocopa, which are strong enough to reach the nectary chamber through the operculum, and large enough to touch the anthers and stigmas during the operation. In many species, the styles, erect in the opening flower, bend and bring the stigma surface close to the stamens, enabling this contact with the pollinators. Some flowers do not show this stigmatic movement and present reduced female fertility. The proportion of fully fertile and male fertile flowers may vary along the flowering season. The long corona filaments, forming an attractive disc tinged with concentric violet stripes and facilitating the insect maintenance on the flower, constitute another adaptation to the pollinator. Most species of subgenus Passiflora are self-incompatible. These adaptations to allogamy contribute to maintain a high genetic diversity in the crops propagated by seeds.

The long-tubed flowers of subgenus Tacsonia, with attractive colors where red is often dominant, are adapted to pollination by hummingbirds, which is also a sign of allogamy. However, the cultivated species of banana passion fruits are self-compatible.

Some Passiflora species (e.g. P. mucronata) are pollinated by bats.

Propagation and cultivation cycle

Passion fruits may be multiplied from seeds or from cuttings. Seeds may show some dormancy (up to about 5 months). Seedlings are produced in nurseries and planted in the field after two to four months. Under tropical conditions, the first flowering generally occur six months after emergence and production begins three months later. In their habitat, Andean species start production 12 to 18 months after planting. The vines remain productive for ten years and more. However, in Brazil and Colombia, plantations of yellow maracuja are often renewed after about two years to maintain higher production and/or keep the crop free of viral diseases.

Origin of cultivated forms

The origin of cultivated passion fruits is rarely an enigma as most of them still exist in the wild, sometimes in directly cultivable forms. They have become naturalized in many tropical countries. But many wild species are disappearing, some without having been described, because of the rapid degradation of their habitats, particularly in the Andean valleys where isolation has favored numerous endemisms.

General references

Killip (1938), Vanderplank (1996), Coppens d’Eeckenbrugge et al. (1997).


 Family chart