A couple of years ago, when I was in Belize with Anne hiking around the rainforest, exploring Mayan power sites, and talking to a range of different plant people, two main species came up over and over: the cockspur acacia (A. cookii, A. cornigera) and the trumpet tree (Cecropia spp). The former was always touted as a remedy for snakebite, and the presence of cardioactive glycosides in its bark may be potentially related to this traditional use (slowing the heart rate and perhaps decreasing the circulation of poison). "It won't cure it", one gentleman told me, "but it will give you time to get to help, even if you have to walk a long distance". Seemed like a useful tip.
The latter, a middle canopy plant known as the trumpet tree, seemed to have a special place in the hearts of nearly everyone I spoke with who knew anything about the jungle. "It's the toucan's favorite". "The stems, which are hollow, can be used as a trumpet". "We use it to communicate with the spirits" (hollow stemmed plants often have this power, as with the Elder tree). "It makes high blood pressure go away". "It helps with men's issues". Fresh research now points to the power of this plant in treating hypertension and the bronchiospasm of asthma. Though these studies are from animal models, I feel more confident about their conclusions (the authors speculate a Ca-channel blocking activity) given the wealth of traditional information that is available.
From Phytomedicine:
Antihypertensive effect
Antispasmodic effect in bronchial asthma
File another one under the "Science plays catch-up" tab.