The Winged bean (Psophocarpus tetragonolobus), a lso
known as the Goa bean and Asparagus Pea and Winged Pea (Lotus
tetragonolobus), is a tropical legume plant native to New Guinea. It
grows abundantly in hot, humid equatorial countries, from the
Philippines and Indonesia to India, Burma, Thailand and Sri Lanka.
It does well in humid tropics with high rainfall. There are also
varieties that can be grown in most areas of the U.S..
The winged bean plant grows as a vine with climbing stems and
leaves, 3–4 m in height. It is an herbaceous perennial, but can be
grown as an annual. It is generally taller and notably larger than
the Common bean. The bean pod is typically 15–22 cm (6–9 in) long
and has four wings with frilly edges running lengthwise. The skin is
waxy and the flesh partially translucent in the young pods. When the
pod is fully ripe, it turns an ash-brown color and splits open to
release the seeds. The large flower is a pale blue. The beans
themselves are similar to soybeans in both use and nutritional
content (being 29.8% to 39% protein).
The plant is one of the best nitrogen fixers with nodulation
accomplished by the soil bacterium Rhizobium. Because of its ability
to fix nitrogen from the atmosphere, the plant requires very little
or no fertilizers.
Being a tropical plant, it is sensitive to frost. Most plants
will not flower if the day length is more than 12 hours, meaning
they will not produce pods in most temperate zones, although day
length neutral cultivars do exist. The seeds have a hard coat and it
helps to soak them before planting to hasten germination. The plant
grows very quickly, reaching a length of four meters in a few weeks.
Uses
This bean has been called the "one species supermarket" because p ractically
all of the plant is edible. The beans are used as a vegetable, but
the other parts (leaves, flowers, and tuberous roots) are also
edible. The tender pods, which are the most widely eaten part of the
plant (and best eaten when under 1" in length), can be harvested
within two to three months of planting. The flowers are often used
to color rice and pastries. The flavor of the beans has a similarity
to asparagus. The young leaves can be picked and prepared as a leaf
vegetable, similar to spinach. The roots can be used as a root
vegetable, similar to the potato, and have a nutty flavor; they are
also much richer in protein than potatoes. The dried seeds can be
useful as a flour and also to make a coffee-like drink. Each of
these parts of the winged bean provide a source of vitamin A,
vitamin C, calcium, iron, and other vitamins . The seeds contain 35%
protein and 18% oil. |
