| A curious, attractive fruit of the Oxalidaceae, the carambola, Averrhoa carambola L., has traveled sufficiently to have acquired a number of regional names in addition to the popular Spanish appelation which belies its Far Eastern origin. In the Orient, it is usually called balimbing, belimbing, or belimbing manis ("sweet belimbing"), to distinguish it from the bilimbi or belimbing asam, A. bilimbi L. In Ceylon and India, the carambola has the alternate names of kamaranga, kamruk, or other variants of the native kamrakh. In Vietnam, it is called khe, khe ta, or similar terms; in Kampuchea, spu; in Laos, nak fuang, or the French name, carambolier; in Thailand, ma fueang. Malayans may refer to it as belimbing batu, belimbing besi, belimbing pessegi, belimbing sayur, belimbing saji, kambola, caramba, or as "star fruit". Australians use the descriptive term, five corner; in Guam, it is bilimbines; to the Chinese, it is yang-táo. Early English travelers called it Chinese, or Coromandel gooseberry, or cucumber tree. In Guyana, it is five | |
The carambola tree is slow-growing, short-trunked with a much-branched, bushy, broad, rounded crown and reaches 20 to 30 ft (6-9 m) in height. Its deciduous leaves, spirally arranged, are alternate, imparipinnate, 6 to 10 in(15-20 cm) long, with 5 to 11 nearly opposite leaflets, ovate or ovate-oblong, 1 1/2 to 3 1/2 in (3.8-9 cm) long; soft, medium-green, and smooth on the upper surface, finely hairy and whitish on the underside. The leaflets are sensitive to light and more or less inclined to fold together at night or when the tree is shaken or abruptly shocked. Small clusters of red-stalked, lilac, purple-streaked, downy flowers, about 1/4 in (6 mm) wide, are borne on the twigs in the axils of the leaves. The showy, oblong, longitudinally 5- to 6-angled fruits, 2 1/2 to 6 in (6.35-15 cm) long and up to 3 1/2 (9 cm) wide, have thin, waxy, orange-yellow skin and juicy, crisp, yellow flesh when fully ripe. Slices cut in cross-section have the form of a star. The fruit has a more or less pronounced oxalic acid odor and the flavor ranges from very sour to mildly sweetish. The so-called "sweet" types rarely contain more than 4% sugar. There may be up to 12 flat, thin, brown seeds 1/4 to 1/2 in (6-12.5 mm) long or none at all.
The carambola is believed to have originated in Ceylon and the Moluccas but it has been cultivated in southeast Asia and Malaysia for many centuries. It is commonly grown in the provinces of Fukien, Kuangtung and Kuangsi in southern China, in Taiwan and India. It is rather popular in the Philippines and Queensland, Australia, and moderately so in some of the South Pacific islands, particularly Tahiti, New Caledonia and Netherlands New Guinea, and in Guam and Hawaii.
The carambola is widely grown from seed though viability lasts only
a few days. Only plump, fully developed seeds should be
planted. In damp peat moss, they will germinate in one week in summer,
require 14 to 18 days in winter. The seedlings are
transplanted to containers of light sandy loam and held until time
to set out. They are very tender and need good care. Seedlings are highly
variable. Air-layering has been practiced and advocated. However, root
formation is slow and later performance is not wholly satisfactory. Inarching
is successful in India, shield-budding in the Philippines and the Forkert
method in Java. Trees can be top-worked by bark-grafting, a popular technique
in Java. For mass production, side-veneer grafting of mature, purplish
wood, onto carambola seedlings gives best results for most workers. The
rootstocks should be at least 1 year old and 3/8 to 5/7 in (1-1.5 cm) thick.
One Florida farmer prefers cleft-grafting of green budwood and has 90%
success. Grafted trees will fruit in 10 months from the time of planting
out. Mature trees can be top-worked by bark-grafting.
The tree needs full sun. A spacing of 20 ft (6 m) has been advocated
but if the trees are on good soil no less than 30 ft (9 m)
should be considered. At the Research Center in Homestead, trees 8
to 10 ft (2.4-3 m) high respond well to 1 lb (0.5 kg)
applications of N, P, K, Mg in the ratio of 6-6-6-3 given 3 to 4 times
per year. If chlorosis occurs, it can be corrected by added iron, zinc
and manganese. Some advisers recommend minor-element spraying 4 times during
the year if the trees are on limestone soils. Moderate irrigation is highly
desirable during dry seasons. Heavy rains during blooming season interfere
with pollination and fruit production. Interplanting of different strains
is usually necessary to provide cross-pollination and obtain the highest
yields.