Excerpts from Jim Conrad's
from the September 21, 2007 Newsletter issued from Sierra Gorda Biosphere
Reserve, QUERÉTARO, MÉXICO
Climbing into the mesquites was a vine with trifoliate leaves and eye-catching fruits, which you can see below:
This is CARDIOSPERMUM HALICACABUM, called Balloon-vine in English, a member of the Soapberry Family, the Sapindaceae, a family not well represented beyond the tropics. Another species you might know in the family is the Golden-rain-tree from Asia, sometimes planted as a street tree and also producing papery-walled fruits.
In the picture I'm holding one of the Balloon-vine's fruit pods from which one side has been removed so you can see how the immature seed is suspended inside the bladder. This is a beautiful example of how a fruit can be adapted for wind dispersal. Bladders fall to the ground, perhaps being blown a good distance from the vine as they fall, then wind can roll them even farther.
Balloon-vines are native to tropical America but it's planted in northern climes where it dies back each winter, and is considered an annual ornamental. In Mississippi it was a weed in my garden and climbed lustily along fences.