Nickerbean Caesalpinia bonduc Caesalpiniaceae
Baybean Canvallia rosea Fabaceae
John is off boat-anizing in the Bahamas, and somebody had to stay in town to do the chores. This week my Palm Beach State College Native Plants Class visited John D. MacArthur Beach State Park on Singer Island, with a brief foray onto the beach, where the Sea Lavender was magnificent. Also fun on the sunny sand are the beans drifted up on the sand as well as growing there, a fascination dating back to my life in the Caribbean. Two beachy beans were around:
Baybean (Canavallia rosea) creeps across the sand, often in the company of its likewise creepy friend Railroad Vine (Ipomoea pes-caprae). Interestingly, the two have almost identical rose-violet flower colors, although of very different structure. Baybean has distinctive trifoliate leaves, hose rose-colored pea-type flowers, and a big thick pod full of tough beans. The beans are the interesting part.
They contain an amino acid called canavanine, which is one of the world’s most interesting poisons due to its insidious mode of action. Canavanine is named for Canavallia, although the toxin occurs in many other legumes. A little background. Proteins are chains of amino acids. They are comprised of about 22 different amino acids, of which canavanine is not properly included. It resembles the legitimate amino acid arginine, and sneaks into proteins in disguise. A chain is as strong as its weakest link. If you eat Baybeans the no-good canavanine infiltrates your proteins where arginine belongs, damaging the protein. It is a case of sabotage, as if a bad spy sneaks into the airplane plant and replaces the good rivets with ones that break apart when stressed, or if you replace “a” with “c” throughout a computer program.
The other seabean prevalent in MacArthur Park is a bristly old friend from the Caribbean, nickerbean (Caesalpinia bonduc). It defends itself before you get to its toxins: the vine is thorny, and the pods looks like a porcupine clam, loaded with hard glossy gray spherical seeds the sizes of grapes. The indestructible seeds have hollow spaces allowing them to float, and float they do, for example all the way from the Caribbean to northern European beaches. I have picked them up from the beach, abraded them until a little white shows through, and sprouted them in a pot, where they grow like a thorny Jack’s Beanstalk.
“Nicker” comes from an old name for marbles, and the seeds do serve as substitute marbles in games. In my experience, the ancient game Wari (Mancala) was popular in Barbados, and nickerbeans turn up as the “marbles” on the board. They make good necklace beads and slingshot ammo too. My favorite website, Wayne’s World, suggests rubbing them rapidly on fabric, which heats them up to a surprisingly high temperature due to their mini-wrinkled surface, and then branding your friend for a comical prank.
Do not try that on your spouse (believe me).