I was recently walking along a local beach, when I spotted a happy couple harvesting the smooth, grey beans from a Caesalpinia bonduc. These sea beans, sometimes known as “sea pearls” or “eaglestones,” can be quite attractive and are occasionally used in crafts. There was nothing creative in my interest, though. I was waiting to see if the lady was going to get her fingers jabbed. You see, the bean is the only visible part of the plant that isn’t coated in spines. Even the underside of the leaves can have spines. The bean pod, in particular, has a remarkably fierce array.
There are only two local, native plants that have ever gained my lasting ire; poison ivy and Caesalpinia bonduc. I had the misfortune of becoming entangled in a Caesalpinia bonduc...once. From that point on, I’ve taken great care on working around them. I assure you, getting ensnared was a painful experience and not too good for the clothing, either. Since that day, I’ve viewed briar as almost a wannabe prickle.
I have always informally known Caesalpinia bonduc as knicker bean, but understand now that it also goes by nicker bean, gray nicker bean, yellow nicker, nickernut, nakkar bean, molucca bean, Warri tree, fever nut, and benga nut. The number of names is not surprising as this plant is pretty much know world-wide throughout the tropics and the beans are not infrequently found washing ashore as far north as the Orkney Islands! Though the plant is considered a Florida native, it also is very well established throughout the Carribean, plus in Africa and India. I don’t know, but it might hard to tell exactly which location was the original place of origin. Knicker bean is seriouly designed for survival. A hard shell protects the seed and, should the bean be taken out to sea by flood or rain waters, extra air room inside the shell provides buoyancy. The bean may float for a very long time and can remain viable for thirty years! Once sprouted, the plant can be very aggressive. Through Caesalpinia bonduc may be referred to as a tree or bush, it is actually in the legume family and can act as a vine, using neighboring trees as a climbing structure, eventually completely overtaking them.
As I watched the couple amass a couple of handfuls of beans, we talked and the question arose, what good is the knicker bean? Other than a pretty seed, what possible use does this spine-laden beach-bane hold? I had no idea and my personal bias sought to limit my visions to maybe nothing more than a defensive hedge. I knew that couldn’t be the truth, so I soon set about researching.
Never could I have been more wrong about a plant.
If properly prepared, Caesalpinia bonduc can have many medicinal uses and has long been used as a source for traditional medicines in many locations across the world. The list curative uses is very extensive. Caesalpinia bonduc has often been used as a key ingredient in treating Malaria and has been known as the “quinine of the poor.” It has been used as a diuretic, fever reducer, expectorant and an effective anti-diarrhetic. Uses also include curing convulsions in infants and hypertension, controlling cerebral hemorrhage, assisting digestion, controlling diabetes and it has even been used to fight parasitic worms. Clinical studies have proven Caesalpinia bonduc components as having true antioxidant and anti-inflammatory properties.
With all of that wonderful news, I will also add a fair warning. Caesalpinia bonduc is also poisonous! Please, do not attempt to create knicker bean curatives, if you are not trained and qualified to do so!
There is one more use for the Knicker Bean plant and probably the best one of all. This plant is a major food source for the larvae of Cyclargus thomasi bethunebakeri, the extremely rare Miami Blue butterfly.