Tree of the Week: That banana is really an herb, not a tree

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The Banana Tree – Musa acuminata

For a tropical plant, the banana tree is amazingly at home in the Los Angeles area: not only does it grow here, after 10 to 15 months of frost-free conditions it actually produces a flower stalk and edible fruit (Sunset zones 21-24 and some below). Its huge leaves convey a tropical look and indicate that serious frost (below 28 degrees F) seldom or never occurs at that location.

The first bananas were known more than 2,000 years ago in Southeast Asia, centered on the Malaysian peninsula; they were inedible, seeded fruits, but crossing produced seedless, edible or cooking varieties which ripened to red or green fruits. Like many fruit trees the plant has a tendency to produce mutations or ‘sports.’ In 1836 the Jamaican Jean Francois Poujot discovered a sweet yellow mutant strain in his orchard, the now familiar dessert fruit; it was introduced to this country in 1876. The California Rare Fruit Growers indicate that some 10 varieties are grown here locally; worldwide the number of cultivars is in the hundreds.

A giant perennial herb rather than a tree, the banana plant grows quickly from underground rhizomes (rootstocks) into a 10 to 25 feet tall and wide plant, depending on variety, with dwarfs half the size of regular trees. The trunk (pseudostem) consists of leaf sheaths wrapped around each other. Many suckers come up from the roots, but only one should be allowed to remain, to replace the fruiting trunk after bearing. Large elliptic green or purple leaves can grow as huge as 9 feet tall and 2 feet wide; protect them from wind if you like to see the leaves whole and the tree standing up straight.

A reflected heat location next to a south wall or a driveway makes for tastier fruit, as does placement at the top of a slope (cold air flows downward); on the other hand the tree may require some afternoon shading to prevent sunburn. The enormous flowerstalk first grows upward, then down; it carries clustered rows of white flowers, covered with purple bracts on the outside. The first 5 to 15 rows are female; later rows centered near the end of the stalk carry sterile male and female parts. The female flowers develop without pollination into clusters of fruits, called hands; each fruit may be from 2½ to 12 inches long and three-quarters to 2 inches wide. Ripening may take eight months.

The trees want full sun and most any soil as long as it is very rich (an old compost pile is great) and lots of water, but no overwatering. In contrast to the tropics they suffer from few pests here: scale, aphids and sooty mold, which can be prevented by controlling ants in the tree.

Several ornamental species of banana are found in the genera Ensete and Musa.

--Pieter Severynen

Thoughts? Comments?