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VEGETABLE SPONGE
Luffa cylindrica (L.) Roem., family Cucurbitaceae

The vegetable sponge is also known as sponge gourd, dishrag gourd, dishcloth gourd, loofah gourd, and smooth loofah (Purseglove 1968*, Whitaker and Davis 1962*). It is grown for food in India, where the young tender fruits of the nonbitter types are eaten fresh like cucumbers, cooked as a vegetable, or used in soups. The seeds yield a colorless, odorless, tasteless oil that can be used in cooking. Its primary use, however, is for the fibrous material inside the mature fruit, which is used in commercial filters and for insulation in pot-holders, bathmats, and related uses (Porterfield 1955).

Except during the war years of 1941-45, Japan has maintained an unbroken monopoly on the production of vegetable sponge filters for industrial purposes (Whitaker and Davis 1962*, Howes 1931). Before World War II, 60 percent of the vegetable sponge imported into the United States was used in filters of marine steam and diesel engines (Purseglove 1968*). Production in other areas of the world has not been too successful (Wester and Boswell 1943).

Plant:

The plant is a vigorous trailing or climbing annual that has a distinctive fetid odor when bruised. The leaves are 3 to 12 inches across, kidney shaped, smooth, and softly pubescent. It is commonly trained on a trellis and pruned to the main stem. The fruit is oblong to cylindrical, 1 to 2 feet in length, and full of strong fibrous cells and numerous seeds. The rind is hard but thin and can be softened when soaked in water about 5 days, when it and the seeds can then be removed leaving only the fiber.

The seeds are planted in hills 3 to 4 feet apart, the plants thinned to one; then it is trimmed and thinned to permit development of only 20 to 25 fruits. About 24,000 fruits per acre may be produced. Some cultivars produce the best vegetables and some produce the best sponge (Purseglove 1968*).

Inflorescence:

The flowers are produced in the leaf axil with 4 to 20 staminate flowers and one pistillate flower in the same axil. The yellow showy flowers are 2 to 5 inches across, with five free petals, five free stamens, and three stigmas. The flower opens in the early morning and is open only 1 day. The pistillate flower has a long, tubular ovary. Singh (1958) reported that L. cylindrica was only monoecious but that other species of Luffa had four types of inflorescences: monoecious, andro- monoecious, gynoecious, and hermaphroditic.

Pollination Requirements:

Vegetable sponge flowers require the transfer of pollen from the staminate to the pistillate flowers during the 1 day a flower is open.

Pollinators:

The vegetable sponge is not wind pollinated. It is pollinated by insects (Purseglove 1968*), principally bees. The number of seeds in a mature fruit would indicate that numerous bee visits may be beneficial.

Pollination Recommendations and Practices:

No recommendations on the need for or supplying of pollinators have been made; however, if the crop were grown on a large scale, the need of supplemental pollination to ensure adequate pollen transfer would doubtless be necessary.

LITERATURE CITED:

HOWES, F. N.
1931. THE LOOFAH INDUSTRY. Kew Roy. Bot. Gard. Bul. Misc. Inform. 5: 266-269.

PORTERFIELD, W. M., JR.
1955. LOOFAH - THE SPONGE GOURD. Econ. Bot. 9: 211-223.

SINGH, S. N.
1958. STUDIES IN THE SEX EXPRESSION AND SEX RATIOS IN LUFFA SPECIES. Indian Jour. Hort. 15: 66-71.

WESTER, R. E., and BOSWELL, V. R.
1943. OBSERVATIONS ON CULTURE AND HANDLING OF THE DISH-RAG GOURD IN MARYLAND. Amer. Soc. Hort. Sci. Proc. 42: 579-584.

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