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Excerpts from Jim Conrad's
Naturalist Newsletter
entry from field notes dated May 6, 2023, on west side of El Bosque de las Hojas on the road connecting Hwy120 and El Doctor; oak, pine and juniper forest on limestone bedrock; elevation ±2650m (8700 ft); Eastern Sierra Madre mountains of east-central Querétaro state, MÉXICO, (N20.88°, W99.62°)
WHITE PASSIONFLOWER IN FRUIT
After being cleared of trees, a steep, rocky slope was densely revegetating with young junipers and a few pines. Numerous leafy vines had draped themselves across the trees' tops, and I wondered what they were. The slope was very steep and fenced off, so I couldn't get close, but from the road a few details could be spotted. The camera had a modest telephoto lens, and later the pictures could be enlarged to see things better; here's one feature that turned up:
Despite the slender shape, the fruit's size, and its dangling from a vine on a long, slender stem, or stipe, suggested a passion fruit, genus Passiflora of the Passionflower Family, the Passifloraceae. Most passion fruits sold in markets are spherical and purple skinned, but over 400 species of Passiflora currently are recognized, and there's plenty of variation among them. But, lacking flowers, could this species be identified?
Above you can see that the leaves are so wilted that it's hard to determine their shapes. However, the leaves' undersurfaces are silvery with pinkish veins and the margins bear small, saw-type teeth. Also, later, by greatly enlarging a telephoto picture, the shot at the right was achieved.
On the leaf's petiole, notice the four or five wart-like bumps, which are glands. Later, for identification purposes, it would be important to know that the glands cluster near the petiole's attachment with the blade, not near the attachment point with the stem. Also, near the petiole's attachment with the blade, the blade's sides project backward a little; the base is "shallowly cordate."
By searching several pictures of the vine-covered area, eventually a leaf in deep shadows turned up hardly wilted at all, revealing its shape, shown at the left. It was like a fig leaf, deeply three-lobed, with a broad, gently curving side opposite its middle lobe.
In the upland, central Mexican region known as the Bajío, where we are, if you have a Passiflora whose leaves are three-lobed like fig leaves, with backward projecting lobes at the blade base (cordate), on petioles with noticeable glands nearer the leaf base than the stem, the mature fruits are longer than 2.5cm (1in), are yellow and more elongate than spherical, then you have PASSIFLORA SUBPELTATA. In English the vine usually is known as White Passionflower, for its blossoms are white.
Passiflora subpeltata is a somewhat common but sporadically occurring vine appearing mostly in disturbed upland forests. It's native from central Mexico south into Guatemala, then from Panamá into northern South America, plus it's been introduced into other tropical countries, where it's become an invasive weed.
The CABI website (Centre for Agriculture and Biosciences International) tells us that as an invasive it climbs into and over vegetation, smothering native plants and reducing plant diversity. Further, CABI says that the vines contain cyanic acid and are thought be poisonous to humans and livestock. The nice-looking fruits are inedible.
On the other hand, the 2014 work by Shanmugam Saravanan and others entitled "Antioxidant, analgesic, anti-inflammatory and antipyretic effects of polyphenols from Passiflora subpeltata leaves – A promising species of Passiflora" is enthusiastic about the plant. There we're told that in India's traditional medicine the leaves of Passiflora subpeltata are used in herbal formulations to treat various pain- and inflammation-related health disorders. Moreover, the leaves are widely consumed as a leafy vegetable. The study concludes that "... the acetone extract of P. subpeltata leaves acquire substantial antioxidant, analgesic, anti-inflammatory and antipyretic properties, and that the extract "has immense scope as a source of a new drug in various pharmaceutical industries and pharmaceutical applications."
So, our passionflower vine at home atop a steep slope's junipers, when out in the world, can be a problem, or something to eat and use, depending on your perspective. Here in its Mexican homeland, however, it's just a vine with flowers pretty enough to be planted in gardens, and certainly it's appreciated by pollinators, and whoever else has co-evolved with it, to feed on its fruits and leaves.