The author of today’s entry is again Lindsay Bourque. Lindsay writes:
Echinocystis lobata is an annual herbaceous vine commonly known as wild cucumber, balsam-apple or mock apple. The species is widely distributed throughout eastern North America, where it is found growing in wet lowland areas. It is also found elsewhere in North America, including British Columbia, as an introduced species. The genus name is derived from the Greek echinos, meaning “hedgehog”, and cystis, meaning “bladder”.
Pictured today is the inflated fruit (though also of interest is its sweetly-scented flowers). These fascinating fruits go out with a bang, having an explosive dehiscence mechanism. Each fruit contains four seeds, which develop under increasing hydrostatic pressure. If birds or small mammals don’t interfere with the fruit before it fully ripens, the fruit will expel its seeds at a speed of 11.5 m/s (PDF)!