I spotted this thing in a thicket along the way to the beach the other day. It had a weird little complicated yellow-green flower, largish three lobed leaves, and was a climbing vine with tendrils. I thought to myself that the flower sure looked like a tiny version of a Passionflower, but discounted it:
Passiflora lutea, the yellow passionflower, is a flowering plant in the family Passifloraceae, native North America, in the eastern and south-central parts of the United States from Pennsylvania west to Kansas, and south to Florida and Texas. It is the northernmost species of Passiflora, occurring slightly further north than P. incarnata, and tolerant of winter temperatures down to −15 °C, and even −30 °C for short periods.
It is a perennial herbaceous climbing or trailing vine that can reach 3–5 m in length. The leaves are trilobed, 3–7 cm long and 3–15 cm broad, with a 5 cm petiole; in the north of its range, it is deciduous. The common name as well as the scientific name refers to the small, 1-1.5 cm diameter chartreuse (yellow-green) or off-white flowers it produces in summer. The flowers are followed by small black berries that contain seeds that are brown and bumpy. P. lutea grows in bright shade to sunny places with moist, rich soil. Very similar to Passiflora suberosa.
Yellow passionflower is often good for butterfly gardens, as it is a host for Gulf fritillaries, julia butterflies (Dryas julia), and zebra longwings (Heliconius charitonius). It is also the only pollen source used by an unusual specialist bee, Anthemurgus passiflorae, which is the sole member of its genus; this rare bee is unusual in that despite its obligate relationship with the plant (oligolecty), it rarely pollinates it.
Passiflora lutea is considered an endangered species in Pennsylvania.
I think I'll keep track of it, and collect some seeds. It would be a fun plant in the garden.