Lantern flowers of the Ceropegia genus open in the post-monsoon hills
September 4, 2026
Late in the monsoon is when the lantern flowers open in the hills south of Pune. Two of them have been turning up over the past several weeks: , logged five times between August 20 and August 28 below Sinhagad fort, around Chirmodi and Phanshi in the Velhe hills, and in Pune itself, and , seen seven times from July 2 into late August from Pune out to Wai and the Panchgani road.Ceropegia is a genus of the milkweed family, and the Western Ghats hold more of its species than almost anywhere else on earth. Most of the local ones live the same way. A tuber sits dormant underground through the eight dry months, sends up a thin twining stem when the rains break, climbs whatever grass or shrub is nearest, flowers in August and September as the monsoon starts to slacken, sets seed, and dies back to the tuber before the ground hardens. The whole above-ground plant exists for a few months a year, which is why a slope that shows nothing in March can carry dozens of them in September.The flower is the reason to go looking. It is a narrow tube, often swollen at the base, whose five petal lobes stay joined at their tips instead of spreading open, so the top of the flower forms a small cage or lantern. In the Eyed Ceropegia the tube is pale and marked with dark, eye-like blotches (the "oculata" in the name), and the lobes carry long, fine purple hairs that move in the slightest breeze. Hairy Ceropegia is a smaller plant, hairy along its stems and leaves as the name says, with a shorter greenish-yellow flower mottled in purple.That lantern is a trap. The flower produces a scent that draws small flies; it offers them no nectar, and in several species studied the scent imitates something the fly is actually hunting for, such as the smell of an injured insect that certain flies feed on. A fly that lands and crawls in finds the inside of the tube slick and lined with downward-pointing hairs, so it slides to the swollen base and cannot climb back out. Down there it blunders against the flower's reproductive column, where pollen is packaged in tiny paired sacs with a clip that snaps onto a leg or the base of the mouthparts. The fly is held for roughly a day. Then the flower begins to wilt, the tube softens and the hairs slacken, and the fly walks out carrying the pollen to the next lantern that fools it. The families involved are mostly the very small flies most people never notice: freeloader flies, grass flies, biting midges and their relatives, a few millimetres long.The tubers have a long human history in these hills too. Several Ceropegia species have edible starchy tubers that were dug and eaten in the Sahyadri, and digging remains one of the pressures on the genus, alongside the loss of the open grassy slopes and rock-edged plateaus where the vines climb. A good many of the Ghats species grow in only a handful of hill ranges each.For anyone walking the Sinhagad or Velhe slopes in the next few weeks, the thing to look for is a thread-thin vine wound through grass or a low shrub, with one or two odd pale tubes standing off it, each topped with a little hairy cage. Look closely at the cage and there may be a fly inside, waiting to be let go.
