BEAN, Big Jack Bean or Sword Bean
QUESTION: A lady placed this big bean on my
desk. I have never seen a
bean of this size. She says the seed came from West Texas. She
to know what it is and if you can eat it. Gideon Jennings, County
ANSWER: This is called a Jack Bean -- Canavalia
ensiformis (L.) or in
your case, probably a Sword Bean -- Canavalia gladiata (Jacq.)
The jack bean and the sword bean are very similar. Other names
them are: Chickasaw lima bean, Brazilian broad bean, coffee bean,
ensiform bean, horse bean, mole bean, go-ta-ki, overlook bean,
bean, watanka, and raba de burro.
In both species, pods reach a length of 10-14 inches, and a width
to 1* inches. Seeds are large, *-* inch long and nearly as broad.
two species differ mainly in the length of the seed hilum (scar).
hilum of sword bean (C. gladiata) is more than one-half the length
the seed, whereas that of the jack bean (C. ensiformis) is only
one-third as long as the seed. Most of the jack beans identified
Texas have been white with a black seed scar, while the sword
been red seeded.
There probably are many varietal and environmental variations
growth habit of the plants; however, it appears that the jack
is bushy in comparison with the vining nature of the sword bean
One gardener noted that one sword bean plant covered his entire
of 400 square feet.
Neither bean has commercial importance in this country. Both are
reported to be edible in the young tender immature stage by slicing
boiling the tender pods, or peeling and using the seeds as broad
Also, reports have indicated the possibility of mild toxicity
when eaten in large quantities. Because of this, the boiling water
should be drained off to remove any poisonous substances coming
beans. Pharmaceutical companies have shown some interest in the
a possible source of the enzyme urease.
Jack Bean-- Canavalia ensiformis-- is naturalized in Texas in
You can see an image of the white Jack Bean at:
You can see an image of the Sword Bean at: