Pollination

Passiflora cincinnata with hover flies. – Click the photo for enlargement

Passiflora tarminiana with fly on an anther, Madeira. Photo: Helene Heide-Jørgensen.

     Species, inclusive Passiflora coerulea, with a short androgynophor and a well-developed corona generally emit a sweet fragrance attractive to bees, bumble bees and other flying insects, which land on the corona from where they can reach the nectar produced in the hypanthium below the so-called operculum (See flower construction). The pollinator gets pollen on the back from the open downward directed anthers.

      In species with a long androgynophor and at the same time often also a long corolla tube, bees and other insects with a short proboscis cannot reach the nectar, and usually they will neither obtain contact to the anthers or stigmas if they should land on the corolla. Some of these species are pollinated by butterflies and the red- and yellow colored species are pollinated by hummingbirds, while a few white colored flowers are pollinated by bats. In this case the long androgynophor ensures that anthers and stigmas come in contact with the pollinators head or body or in the case of butterflies primarily the wings. The corona does not emit a scent and the filaments are highly reduced since the corona is not to serve as a landing site. The open anthers do not turn downwards against the corolla but outwards towards the surroundings where the pollinator hangs floating in the air. In the subgenus Passiflora there is a group (Tacsonia) in the northern Andes with 61 species where the corolla tube in most of the species is 10-15 cm long. Only the hummingbird Ensifera ensifera has a 10 cm long beak and a tongue long enough to reach the nectar in these flowers and the distribution area of the hummingbird and Tacsonia group are coincident. This hummingbird also pollinates certain parasitic plants in the family Loranthaceae, where the flowers have a similarly long corolla tube (Heide-Jørgensen 2008).

     At least five species (among these Passiflora mucronata and P. penduliflora) are pollinated by bats such as Glossophaga soricina. These passion flowers have white or greenish fragrant flowers opening in the evening. The corolla tube is broad, corona filaments are short, and the androgynophor is bent aside to make admittance to the flower more easy for the snout and tongue of the bats.

     In Denmark, the flowers are often visited by hover flies (Syrphidae) and wasps and these insects can occasionally function as pollinators. Whether flies also pollinate some Passiflora species in nature is unknown. It is often necessary to perform hand-pollination to ensure fruit production in the edible species.

H. S. Heide-Jørgensen, August 2021.

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