Though many species of Passionflower exist and many cultivars are grown for their edible fruits, I'm guessing that our vines are PASSIFLORA EDULIS var. FLAVICARPA. Passiflora edulis has a purple-fruited variety and a yellow-fruited one, and the picture shows the latter, with the fruit just beginning to ripen.

Above the fruit has been cut open to reveal its many semi-hard seeds embedded in their pulpy arils. The aril in passion fruits is the outer covering of the seed, and it arises from the seed's hilum or funiculus. The funiculus is the "umbilical cord" connecting the fruit wall with the seed. You can see macaroni-like funiculi in the picture appearing as stalks arising from the fruit's inside wall. A seed's hilum is the scar or mark indicating the point of attachment of the seed with its funiculus. In the US we often run into fruiting Hearts-a-bustin', genus Euonymus, in which the seeds are enclosed in orange-colored aril that attract birds to come eat the seeds and transport them to parts unknown.

Another distinguishing feature of passion fruits is the tough stem affixed at the fruit's base. That stem is what becomes of the stalk upon which a passion flower's ovary perches inside the flower. You can clearly see the ovary's stalk (known as the gynophore) in the second and third pictures on our Passion-Flower page at http://www.backyardnature.net/fl_passn.htm.

Passion fruits are good to eat, though our yellow variety is a bit tart to eat without adding lots of sweetening. A delicious drink is made by blending the fruit pulp with ice, water, sugar, and a pinch of bicarbonate of soda. The juice is an excellent source of Vitamin C.

from the May 9, 2010 Newsletter issued from Hacienda Chichen Resort beside Chichén Itzá Ruins, central Yucatán, MÉXICO
YELLOW PASSION-FRUIT FLOWERING
In last February's Newsletter we met our fruiting Yellow Passion Fruit vines, shown above. Now those same vines are flowering, gorgeously so. You can see a three-inch-across (7.5 cm) blossom  below.

(By the way, passionflower blossoms display some unusual anatomy. You might enjoy figuring out what the various parts are of the blossom in the above picture by referring to my Passionflower page, with parts labeled, at http://www.backyardnature.net/fl_passn.htm.)