Chapter 9: Crop Plants and Exotic Plants

BLACK PEPPER AND WHITE PEPPER¹⁷Piper nigrum L., family Piperaceae
The plant that yields ground pepper is not grown commercially in the United States, but it is an important one worldwide. In terms of usage and value, pepper is the most important of all spices in world trade. The United States imports 35 to 40 million pounds annually. India and Indonesia account for about two-thirds of the world production. Some pepper is produced in Brazil for 10 days but that it is at its peak of receptivity after (Kevorkian 1964). It has been grown experimentally 3 to 4 days. under glass in Maryland (Creech 1955).
__________
¹⁷ See "Pepper, Green," p. 292.

Plant:
Piper nigrum is a strong, somewhat woody, perennial evergreen vine that may climb to 30 feet in its preferred hot, wet, nonseasonal climates. Under cultivation, growth is usually held to 10 to 15 feet. The plant has oval, dark-green leaves, as much as 7 by 4 inches in size, that arise at the nodes. Hardwood posts or trees provide columnar support for the vines that may reach 5 feet in width (Purseglove 1968 *). There are many cultivars.

The fruit, called a corn, is 1/4 to l/5 inch in diameter and is picked just before it ripens. The corns are separated from the stems, then dried in a manner similar to coffee drying. Within 2 to 3 days, the pericarp turns black. If the corns are ground while in the pericarp, the product is black pepper. If the black pericarp is removed before the fruit is ground, the product is white pepper (Blacklock 1954, Gentry 1955).

Inflorescence:
The flowers are borne on the vine, at the node opposite the leaves, in catkins or spikes. A spike may have 50 to 150 rather inconspicuous yellowish green apetalous florets only 1 to 3 mm in diameter. The florets are usually hermaphrodite but may be unisexual, with staminate and pistillate flowers on the same plant or on separate plants. Frequently, the florets are unisexual near the base of the spike and hermaphrodite toward the tip. Flowering begins at the base and continues to the tip over a 7- to 8-day period (Ridley 1912* Gentry 1955)

The hermaphrodite floret is protogynous, the two to three stamens appearing at the base of the ovary only after the star-shaped stigma with its three to five rays has matured (Cobley 1956*). The stigma may be receptive for 10 days with peak receptivity at 3 to 5 days (Purseglove 1968*). The pollen is then released in gelatinous masses to pollinate receptive stigmas of other flowers. The unilocular ovary produces only one seed. The stigmatic rays are coated with long tubular hairy growths with their tips somewhat bulbous. The feltlike surface acts as a medium for trapping the pollen grains (Anadan 1924).

Pollination Requirements:
Because of the protogynous nature of Piper nigrum, self-pollination of the floret is impossible. Cobley (1956*) stated that cross-fertilization was the rule, but he apparently referred to transfer of pollen between flowers on a plant rather than between plants. Martin and Gregory (1962) concluded that self-pollination between flowers on a plant was undoubtedly the rule. Free (1970*) stated that the stigma may be receptive for 10 days but that it is at its peak of receptivity after 3 to 4 days.

Pollinators:
Anadan (1924) and Menon (1949) considered rain as the pollinating agent of Piper nigrum. This was supported by the observation by Anadan (1924) that a vine protected from rain failed to set fruit. Martin and Gregory (1962) stated that wind pollination, with or without rain, was not very effective. They believed that self-pollination was undoubtedly the rule, but they did not explain how the pollen might have been transferred from the anthers of one flower to receptive stigmas of another. Cobley (1956*) attributed the transfer of pollen to wind, rain, and ants. Free (1970*) stated that pollination was the result of gravity possibly aided by rain or wind. Purseglove (1968*) stated that although the pollen was in gelatinous masses, a light rain would break up these masses, then the pollen grains would be dispersed and finally caught in the papillae of the stigma. He concluded that the degree to which insects assist in pollination is not known. Martin and Gregory (1962) stated that no insects, large or small, visited the spikes. Anadan (1924), as previously mentioned, stated that a vine protected from rain failed to set, even with bees. He did not elaborate on the kind or activity of the bees. No other observer mentioned visitation of the flowers by bees. It is not clear, therefore, the degree to which insects pollinate Piper nigrum.

Pollination Recommendations and Practices:
None.

LITERATURE CITED:
ANADAN, N.
1924. OBSERVATIONS ON THE HABITS OF THE PEPPER VINE WITH SPECIAL REFERENCE TO THE REPRODUCTIVE PHASE. Madras Dept. Agr. Yearbook 1924: 49-69.

BLACKLOCK, J. S.
1954. A SHORT STUDY OF PEPPER CULTURE WITH SPECIAL REFERENCE TO SARAWAK. Trop. Agr. [Trinidad] 31: 40-56.

CREECH, J. L.
1955. PROPAGATION OF BLACK PEPPERS. Econ. Bot. 9: 233-242.

GENTRY, H. S.
1955. INTRODUCING BLACK PEPPER INTO AMERICA. Econ. Bot. 9: 256-268.

KEVORKIAN, A. G.
1964. PEPPER, VANILLA, AND OTHER SPICES. U.S. Dept. Agr. Yearbook 1964: 195-200.

MARTIN, F. W., and GREGORY, L. E.
1962. MODE OF POLLINATION AND FACTORS AFFECTING FRUIT SET IN PIPER NIGRUM L., IN PUERTO RICO. Crop Sci. 2: 295--299.

MENON, K. K.
1949. THE SURVEY OF POLLU AND ROOT DISEASES OF PEPPER. Indian Jour. Agr. Sci. 19: 89-136.