The Probert Encyclopaedia of Nature

BANANA

The banana is a perennial herb cultivated in tropical and sub tropical climates. Bananas are fast-growing, arising from underground rhizomes. The fleshy stalks or pseudostems formed by upright concentric layers of leaf sheaths constitute the functional trunks. The true stem begins as an underground corm which grows upwards, pushing its way out through the centre of the stalk 10 to 15 months after planting, eventually producing the terminal inflorescence which will later bear the fruit. Each stalk produces one huge flower cluster and then dies. New stalks then grow from the rhizome. The large rectangular or elliptic leaf blades are extensions of the sheaths of the pseudostem and are joined to them by fleshy, deeply grooved, short petioles. The leaves unfurl, as the plant grows, at the rate of one per week in warm weather, and extend upward and outward , becoming as much as 2.5 meters long and 0.75 meters wide. They may be entirely green, green with maroon patches, or green on the upper side and red-purple beneath. The leaf veins run from the mid-rib straight to the outer edge of the leaf. Even when the wind shreds the leaf, the veins are still able to function. Approximately 44 leaves will appear before the inflorescence. The banana inflorescence shooting out from the heart in the tip of the stem, is at first a large, long-oval, tapering, purple-clad bud. As it opens, the slim, nectar-rich, tubular, toothed, white flowers appear. They are clustered in whorled double rows along the floral stalk, each cluster covered by a thick, waxy, hood like bract, purple outside and deep red within.

The flowers occupying the first five to fifteen rows are female. As the rachis of the inflorescence continues to elongate, sterile flowers with abortive male and female parts appear, followed by normal staminate ones with abortive ovaries. The two latter flower types eventually drop in most edible bananas. The ovaries contained in the first (female) flowers grow rapidly, developing parthenocarpically into clusters of fruits, called hands. The number of hands varies with the species and variety.

The fruit (technically a berry) turns from deep green to yellow or red, and may range from ten centimetres to thirty centimetres in length and two centimetres to five centimetres in diameter. The flesh, ivory-white to yellow or salmon-yellow, may be firm, astringent, even gummy with latex when unripe, turning tender and slippery, or soft and mellow or rather dry and mealy or starchy when ripe. The flavour may be mild and sweet or slightly acid with a distinct apple tone. The common cultivated types are generally seedless with just vestiges of ovules visible as brown specks. Occasionally, cross-pollination with wild types will result in a number of seeds in a normally seedless variety.
Research Banana