Growth Habit: Bananas are fast-growing herbaceous perennials 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 center of the stalk 10-15 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. Banana plants are extremely decorative, ranking next to palm trees for the tropical feeling they lend to the landscape.

Foliage: The large oblong 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 9 feet (2.74 meters) long and 2 feet (0.61 meters) wide. They may be entirely green, green with maroon splotches, 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.

Flowers: Upon flowering, the true stem or growing point emerges from the center of the tightly rolled bunch of leaves. This odd-looking “flower cluster” is actually an elongated, plump, purple to green “ bud ” (sometimes called the “bell” or “heart”), which at first displays large female flowers (whose ovaries ripen into fruit). As the “ bud ” elongates, it exposes semicircular layers of female flowers, then neutral flowers, and finally small, generally non-functional (with no viable pollen) male flowers. Each group of flowers is arranged radially on the stem in nodal clusters. Each flower cluster is borne on a prominence on the stem bearing the fruit (peduncle) and covered by a bract. About 12–20 flowers are produced per cluster. Collectively, the flowering parts and fruit are referred to as the bunch. Individual clusters of fruits are known as hands, and individual fruits are known as fingers.

Fruits: Musa fruits are variable in size, shape, and color. They are generally elongate-cylindrical, straight to strongly curved, 3–40 cm (1.2–16 in) long, and 2–8 cm (0.8–3 in) in diameter. The fruit apex is important in variety identification; it may be tapered, rounded, or blunt. The skin is thin and tender to thick and leathery, and silver, yellow, green, or red in color. Inside the ripe fruit, the flesh ranges from starchy to sweet, and in color from white, cream, yellow, or yellow-orange to orange. Bananas also vary in peel thickness. Some varieties have a thin peel and are more susceptible to damage in transport, whereas others have a comparably thicker peel.

Source: http://www.crfg.org/pubs/ff/banana.html

The edible bananas are restricted to tropical or neartropical regions, roughly the area between latitudes 30°N and 30°S. Within this band, there are varied climates with different lengths of dry season and different degrees and patterns of precipitation. A suitable banana climate is a mean temperature of 80°F (26.67°C) and mean rainfall of 4 in (10 cm) per month. There should not be more than 3 months of dry season.

Cool weather and prolonged drought retard growth. Banana plants produce only one leaf per month in winter, 4 per month in summer. If low temperatures occur just at flowering time, the bud may not be able to emerge from the stem. If fruits have already formed, maturity may be delayed several months or completely suspended. If only the leaves are destroyed, the fruits will be exposed to sunburn. Smudging, by burning dry trash covered with green clippings to create smoke, can raise the temperature 2 to 4 degrees. Flooding the field in advance of a cold snap will keep the ground warm if the chill weather is brief. In Australia, bananas are planted on sunny hill sides at elevations of 200 to 1,000 ft (60 to 300 m) to avoid the cold air that settles at lower levels. Brief frosts kill the plants to the ground but do not destroy the corm. 'Dwarf Cavendish' and the 'Red' banana are particularly sensitive to cold, whereas the dwarf cultivar 'Walha', or 'Kullen', of India is successful up to 4,000 ft (1,220 m) in the outer range of the Western Ghats. 'Vella vazhai' is extensively cultivated in the Lower Pulneys between 3,200 and 5,500 ft (975 and 1,616 m). A cooking banana, 'Plankel', survives winters in home gardens in northern India. In South Africa, the main banana-producing area is along the southeast coast at 3,000 ft (915 m) above sea level with summer rainfall of 35 to 45 in (90-115 cm). The major part of the crop in East Africa is grown between 4,000 and 5,000 ft (1,220 and 1,524 m) and the total range extends from sea-level to 7,500 ft (2,286 m).

Wind is detrimental to banana plants. Light winds shred the leaves, interfering with metabolism; stronger winds may twist and distort the crown. Winds to 30 mph break the petioles; winds to 40 mph will topple a pseudostem that is supporting the weight of a heavy bunch unless the stem is propped, and may cause root damage in non fruiting plants that are not blown down; winds of 60 mph or over will uproot entire plantations, especially when the soil is saturated by rain. Windbreaks are often planted around banana fields to provide some protection from cold and wind. Cyclones and hurricanes are devastating and the latter were the main reason for the shift of large scale banana production from the West Indies to Central America, Colombia and Ecuador. Hail results from powerful convection currents in the tropics, especially in the spring, and does much damage to bananas.

Edible bananas originated in the Indo-Malaysian region reaching to northern Australia. They were known only by hearsay in the Mediterranean region in the 3rd Century B.C., and are believed to have been first carried to Europe in the 10th Century A.D. Early in the 16th Century, Portuguese mariners transported the plant from the West African coast to South America. The types found in cultivation in the Pacific have been traced to eastern Indonesia from where they spread to the Marquesas and by stages to Hawaii.

Source: http://www.hort.purdue.edu/newcrop/morton/banana.html