Floral Abnormalities in Jack

Abstract

The Jack tree (Artocarpus integrifolia, L.) is monoscious, bearing spikes of male and female flowers. The spikes are enclosed in stipules when young. Numerous male spikes are produced and within three weeks of its emergence from the stipule the male spike drops off, while the female develops into the so-called jack fruit. The latter as is well known, is a large multiple fruit with a spinescent appearance. Each spine represents the hardened apex of a perianth. These apices fuse together and form the spiny rind of the fruit. The female inflorescence has a number of fertile flowers and numerous sterile ones surrounding the fertile ones. The stigmas appear at the end of each spine. In a fertile flower the perianth enlarges, becoming succulent and enclosing a pericarp with a single seed. The unfertilised ones thicken out into flat ribbons and are often edible. An aborted seed and pericarp are found in these. The steriles develop into the whitish flakes filling up the intervening space. The colour of the edible flakes varies from pale yellow to reddish orange. At the Agricultural Research Station, Pattambi, a study is being conducted on this fruit plant, maintaining a collection of about 160 trees. The number of female spikes in a tree may vary from 3 to 40 per cent of all the spikes produced and they take 90 to 110 days to mature.