Common name: Giant sensitive plant.
Giant sensitive plant is a shrub native to South America. The branches are square in shape and have a yellowish grey appearance. The entire plant is covered with recurved yellow colored prickles. Giant sensitive plant does not grow very tall, but spreads out horizontally with arching branches which can grow to more than 5 meters. Left alone, this plant forms wide impenetrable thick lets. This plant is commonly found on Palakkad road-sides and in some parts of Tamilnadu. Globally, in some areas it is considered as an invasive plant. The leaves are arranged in an alternate manner and is bipinnate. The entire leaf measurers around 9.5 cm in length; about 8 pairs of pinnae are seen; the leaflet (sessile) which number to more than 40 pairs are arranged in an opposite manner. The leaflets measure around 2 mm each. The leaflets are sensitive to touch. The inflorescence occur at branch ends; the flower heads are pink in color and globular in shape. The fruit is in the form of a dark colored pod-several such pods are arranged in clusters in the leaf axis. Each pod contains 3-4 seeds which are yellow in color and ovate in shape.