Defences There is an extraordinary special relationship between Passiflora and the Heliconius butterflies known as Longwings. (Their classification is in doubt, I think being thought of either from the Heliconiinae subfamily of Nymphalidae or Heliconiidae family within the Papilionoidea.) This is a uniquely uneasy relationship however as, although each needs the other, at the same time there is a constant battle of wits. These beautiful insects, which often appear to fly in slow motion, almost always lay their eggs on passion flowers. The eggs are usually laid singly, though sometimes in groups. The larvae (caterpillars), which may have irritant spines, then hatch out & eat the leaves of the plant. In sufficient numbers they will destroy it. At the same time however in some species the adults will pollinate the flowers. The table here shows the battle in progress. These are clever plants. They have a number of different defences to try to prevent butterflies laying their eggs on them. The reason they object to this is that the eggs hatch out into voracious caterpillars whcih can severely damage or even kill the plants. The sophistication of the defences gives an insight into the evolutionary pressures on these plants. Defences include:- Mimicry Butterfly egg mimicry as on the growing tips, petioles and stipules of P. actinia above and the growing tips of P. holosericea. See possible larvae (caterpillar) mimicry on P. 'Byron Beauty'. Any butterfly that sees eggs from another butterfly on a plant will not lay its own eggs as they would ripen after the ones already there and would have little food i.e. leaves to eat. In the case of P. pinnatistipula what appears to be another tactic, mimicry of an insect predator which might eat the eggs. Drooping growing tips A drooping growing tip on P. helleri typical of many passion flowers. This suggests to butterflies & other predators that the plant is in poor condition & wilting & so is less appealing either as a snack or as a future food source for eggs that may then be laid elsewhere.D r Changing leaf shape. Butterflies have very sharp eyesight and look for leaf shapes that match their template of what a suitable plant for egg laying should look like. A number of Passiflora change their leaf shape to try to throw them off the scent. P. suberosa is well known for this and I have a nice sequence of different leaf shapes on P. colinvauxii here. Even the Common Passion Flower varies its number of leaf lobes. Toxic foliage and fruit Foliage which becomes toxic when attacked by herbivores from caterpillars to donkeys. Fruit which remain toxic until they are ripe.
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Passiflora defences
