Artful Aristolochia

Looking up the glass ceiling of the greenhouse at Teplice Botanical Garden, I was surprised by the sight of Aristolochia gigantea flowers dangling everywhere - each bloom is larger than a human head.

These flowers look and smell like rotten meat, but they are really much smarter. On the first day of opening (anthesis), the flower is in female phase during which flies, fooled by the sight and smell, enter a chamber via a constricting entrance lined by inward pointing hairs. This is where the reproductive structure(gynostemium) sits.

And there, they are trapped, but not too long - just 1 day, which gives them sufficient time to deposit pollen collected previously from another flower onto the stigma.

The next day, the flower change sex into a male and the fly is dusted with a new pollen coat once more. Soon, the hairs lining the entrance became flaccid and the fly can leave at will to visit another female flower - and repeat the ordeal.
At Dresden Botanical Garden, I saw a less well-known member of the family - Pararistolochia promissa, much smaller in size but no less intriguing nor pungent. This is a predominantly tropical African genus (with only 1 Asian species so far) that differs from the usual Aristolochias by having fleshy, colourful fruits rather than dry brown capsules. Most likely, it rely on fruit eaters for dispersal. And like its bigger cousin, it uses the same trick to get some. This plant is still restraining its unwilling runner in its smelly jail cell.