The Mexican lime tree is exceedingly vigorous; may be shrubby or range from 6 1/2 to 13 ft (2-4 m) high, with many slender, spreading branches, and usually has numerous, very sharp, axillary spines to 3/8 in (1 cm) long. The evergreen, alternate leaves are pleasantly aromatic, densely set; elliptic- or oblong-ovate, rounded at the base, 2 to 3 in (5-7.5 cm) long, leathery; light purplish when young, dull dark-green above, paler beneath, when mature; with minute, rounded teeth and narrowly-winged petioles. Faintly fragrant or scentless, the axillary flowers, to 2 in (5 cm) across are solitary or 2 to 7 in a raceme, and have 4 to 6 oblong, spreading petals, white but purple-tinged when fresh, and 20-25 bundled white stamens with yellow anthers. The fruit, borne singly or in 2's or 3's (or sometimes large clusters), at the twig tips, is round, obovate, or slightly elliptical, sometimes with a slight nipple at the apex; the base rounded or faintly necked; 1 to 2 in (2.5-5 cm) in diameter; peel is green and glossy when immature, pale-yellow when ripe; somewhat rough to very smooth, 1/16 to 1/8 in (1.5-3 mm) thick; the pulp is greenish-yellow in 6 to 15 segments which do not readily separate; aromatic, juicy, very acid and flavorful, with few or many small seeds, green inside.
Origin and Distribution
The Mexican lime is native to the Indo-Malayan region. It was unknown in Europe before the Crusades and it is assumed to have been carried to North Africa and the Near East by Arabs and taken by Crusaders from Palestine to Mediterranean Europe. In the mid-13th Century, it was cultivated and well-known in Italy and probably also in France. It was undoubtedly introduced into the Caribbean islands and Mexico by the Spaniards, for it was reportedly commonly grown in Haiti in 1520. It readily became naturalized in the West Indies and Mexico, There is no known record of its arrival in Florida. Dr. Henry Perrine planted limes from Yucatan on Indian Key and possibly elsewhere. In 1839, cultivation of limes in southern Florida was reported to be "increasing". The lime became a common dooryard fruit and by 1883 was being grown commercially on a small scale in Orange and Lake Counties. When pineapple culture was abandoned on the Florida Keys, because of soil depletion and the 1906 hurricane, people began planting limes as a substitute crop for the Keys and the islands off Ft. Myers on the west coast. The fruits were pickled in saltwater and shipped to Boston where they were a popular snack for school children. The little industry flourished especially between 1913 and 1923, but was demolished by the infamous hurricane of 1926. Thereafter, the lime was once again mainly a casual dooryard resource on the Keys and the southern part of the Florida mainland.
In 1953, George D. Fleming, Jr., proprietor of Key Lime Associates, at Rock Harbor, on Key Largo, was the chief producer of limes. Though he had sold several of his groves, he was developing a new one as part of a "vacation cottage colony".
Fearing that this little lime might disappear with lack of demand and the burgeoning development of the Keys, the Upper Florida Keys Chamber of Commerce launched in 1954, and again in 1959 with the help of the Upper Keys Kiwanis Club, an educational campaign to arouse interest and encourage residents to plant the lime and nurseries to propagate the tree for sale.
The Mexican lime continues to be cultivated more or less on a commercial scale in India, Egypt, Mexico, the West Indies, tropical America, and throughout the tropics of the Old World. There are 2,000,000 seedling trees near Colima, Mexico. Mexico raises this lime primarily for sale as fresh fruit but also exports juice and lime oil. New plantings are being made to elevate oil production. In 1975, Rodolfo Guillen Paiz, Chief of the Citrus and Tropical Fruit Subproject of ANACAFE in Guatemala, reported the initiation of a program to establish the Mexican lime as an all-year commercial crop for the fresh fruit market, the production of juice and lime peel oil, and, as a first step, the creation of a collection of selections as a genetic base for development of an industry, possibly in association with cattle-raising since it had been observed that cattle do little damage to the trees.
Production of Mexican limes for juice has been the major industry on the small Caribbean island of Dominica for generations. There are at least 8 factories expressing the juice which is exported largely to the United Kingdom in wooden casks after "settling" in wooden vats and clarifying. In England, it is bottled as the world-famous "Rose's Lime Juice" put out by L. Rose & Co., Ltd., or as the somewhat different product of the chief competitor, A. C. Shellingford & Co. Surplus juice, over their requirements, is sold to soft-drink manufacturers. Since 1960, Rose has produced lime juice concentrate in Dominica for export. There is also considerable export of lime oil distilled from lime juice and oil expressed from the whole fruit. Jamaica, Grenada, Trinidad and Tobago, Guyana, and the Dominican Republic export lesser amounts of juice and oil. But the Dominican Republic has recently enlarged its plantings in order to increase its oil output. Montserrat ships only juice. Ghana is now the leading producer of lime juice and oil for L. Rose & Co., Ltd. Gambia began serious lime processing in 1967.
The Mexican lime grows wild in the warm valleys of the Himalayas and is cultivated not only in the lowlands but up to an elevation of 4,000 ft (1,200 m). It was first planted on the South Pacific island of Niue in 1930. A small commercial industry has been expanding since 1966. Some of the fruit is sold fresh but most of the crop is processed for juice and oil by the Niue Development Board Factory. These products are shipped to New Zealand, as are a good part of the peels for the manufacture of marmalade and jam. Production was crippled by a hurricane in 1979. This storm inspired a search for rootstocks that could be expected to withstand strong winds.
There are few varieties of the Mexican lime, except for several spineless selections, inasmuch as there is no great variation in the wild or under cultivation. Some old named cultivars may not be recognized today.
'Everglade' (Philippine Islands #2182')a seedling of a Mexican lime pollinated by flowers of a grapefruit or pummelo, but the fruits show no grapefruit or pummelo characteristics. Introduced into Trinidad in 1922. Planted in the Citrus Experiment Station collection at Riverside, California, it showed little or no distinguishing features. It is limelike, elliptical, with fairly large nipple at apex; 1 1/2 to 2 in (4-5 cm) wide, 1 3/4 to 2 1/8 in (4.5-5.4 cm) high; peel light-yellow when ripe, medium-smooth, the largest oil glands slightly sunken; thin, about 1/16 in (1.5 m); pulp light-greenish, in 8 to 10 segments with tender walls; aromatic, very juicy, of excellent quality and texture; the flavor sprightly acid; seeds 2 to 10, averaging about 5. The fruits are borne in large clusters because all the flowers are perfect. Tree is highly susceptible to withertip.
'Kagzi'the name given the Mexican lime most commonly cultivated throughout India. It is represented by numerous subtypes differing slightly in size, shape and color.
'Palmetto'a selected seedling from a Mexican lime pollinated by the 'Sicily' lemon; first described by Dr. H.J. Webber in the United States Department Yearbook for 1905; elliptical or nearly round with small nipple at apex; small of size, 1 3/8 to 1 1/2 in (3.6-4 cm) wide; 1 3/8 to 1 3/4 in (3.6-4.5 cm) high; peel pale-yellow when ripe, smooth, very thin, less than 1/16 in(1.5 mm); pulp light greenish-yellow, in 8 to 10 segments; tender, very juicy, of fine quality, aromatic, with sprightly acid flavor; usually 3 to 6 seeds.
'Yung' ('Spineless Mexican')of unknown origin; was introduced into California from Mexico by George Yung around 1882.
Another spineless sport was reported in Dominica in 1892 and apparently the same was sent to the United States Department of Agriculture from Trinidad in 1910, and several thornless sports were found in lime groves near Weslaco, Texas, after a 1925 freeze. In 1967, seeds of a lime tree seen flourishing in the desert at Yuma, Arizona were brought to southern Florida by Burt Colburn and planted. Of 50 resulting seedlings, 8 were practically thornless. Budwood from these was grafted onto rough lemon stock for distribution.
In Trinidad, hybridization was undertaken in 1925 in the hope of developing a type immune to withertip. A seedling selection from hybrids was labeled 'T-l'. The fruits were not as juicy in the green stage and a bit larger than the typical Mexican lime. Back-crossing was done to arrive at 'T-145' more closely resembling a typical Mexican lime in size.
The Mexican lime is more sensitive to cold than the lemon, and can be grown only in protected locations in California. It thrives in a warm, moist climate with annual rainfall between 80 and 150 in (203-381 mm). Nevertheless, it tolerates drought better than any other citrus fruit. When there is excessive rainfall, the tree is subject to fungus diseases.
The oolitic limestone of the Florida Keys seems perfectly acceptable to the Mexican lime. The tree grows reasonably well in a variety of other soils. In sandy locations on the Florida mainland, best growth is achieved by the periodic addition of lime to raise the pH. Other-wise there will be a lighter crop of fruits; they will be larger than normal with thicker peel and less juice. In Hawaii, this lime is cultivated in rich sandy or gravelly, well-drained soil. Porous lava soil is acceptable if there is abundant rainfall. Stiff clay soils are unsuitable. On the island of Niue, limes are grown on a thin layer of topsoil underlain with limestone. Farmers are advised to avoid breaking up the limestone too much and mixing excessive calcium with the topsoil.
The Mexican lime is usually propagated by seed because most seeds are polyembryonic and reproduce faithfully to the parent. In some areas, root sprouts from mature trees are taken up and transplanted into groves. Sprouting may be encouraged by digging around the parent tree to sever the roots wholly or partly. Cuttings of mature wood may also serve for propagation but usually do not develop strong root systems. Selected clones have been budded onto rough lemon or sour orange. The latter is said to provide more resistance to hurricanes. Pummelo has been used in Hawaii but doesn't make a perfect union. In Indonesia, this lime has always been air-layered. In the 1940's, air-layering became popular in Florida. It was adopted in India with 100% success, using indole butyric acid to aid root development of the 'Kagzi' lime.
In pioneer days, people on the Florida Keys had unsophisticated methods of raising limes. They often sowed the seeds thickly in a pot-hole in the limestone having a bit of soil in the bottom. When the seedlings were a few inches high, they were taken up and transplanted during the rainy season into any pot-hole with enough soil to sustain them until the roots were strong enough to penetrate the porous rock. The result was irregular groves, and this practice was called "jungle" planting. Sometimes volunteer seedlings would be taken up from beneath fruiting trees and transplanted in the same manner. Later on, growers began to dynamite holes in a regular pattern in order to have uniform rows. The breaking up of the rock enhanced root development.
The trees are best set 25 ft (7.5 m) apart each way, which allows for 70 trees per acre (28/ha). Closer spacings of 15 or 20 ft (4.5-6 m) do not permit enough room for good cultural practices. For many years, the trees on the Keys were fertilized only by a mulch of cured seaweed. On the mainland, nitrogen was supplied by leguminous cover crops such as velvet bean (Mucuna deeringiana Merr.), beggarweed (Desmodium canum Sch. & Thell.), or Showy Crotalaria (Crotalaria spectabilis Roth.). Dade County growers came to apply commercial fertilizer, using a 2-8-10, or 2-10-10 NPK formula. Increasing potash is a means of checking growth and promoting fruiting.
Before planting, in Niue, 1 to 2 tablespoons of zinc sulphate are placed in each hole. One month later, and then every 4 months thereafter, 3 1/2 oz (100 g) of mixed nitrogen and potassium are applied around the base. In the second year, the amount given is 18 oz (500 g) in 3 applications; in the third year, 3.3 lbs (1.5 kg); in the 4th year, 6.5 lbs (3 kg) and the 5th year and beyond, 9 lbs (4.5 kg).
Seedlings will begin to fruit in 3 to 6 years and reach full production in 8 to 10 years. The fruits ripen and fall 5 to 6 months after flowering. Trees grown from air layers or cuttings tend to fruit the first year and then cease fruiting until they have attained some growth. If the trees have been correctly pruned when young, there is no further need for pruning except to remove deadwood and water-sprouts, or for the purpose of thinning the fruits to increase size.
On the Florida Keys, the trees produce some fruits more or less the year around, but there are two main seasonsMay/June and November/December. The peak season on Niue is in April and May. The fruits may be picked while still somewhat green for home use or for the fresh fruit market, but grove workers are reluctant to pick them because of the thorniness of the tree, unless they are provided with protective gloves. If picked too soon, the peel is apt to develop a dark "rind scald". The ideal stage is when the color has changed from dark to light green, the surface is smooth and the fruit feels slightly soft to the touch. For processing, the fully ripe, yellow limes are gathered from the ground twice a week. Because of the rough ground, pioneer growers on the Keys collected the fruits with wheelbarrows pushed along boards placed over the limestone.
The Mexican lime ripens to full yellow and loses weight rapidly at normal room temperature in warm climates. In the home, the fruits can be held fresh for 2 or 3 weeks if kept in water in a closed jar. They are prone to cold injury under refrigeration at 44.6º F (7º C). A storage temperature of 48.2º F (9º C) with 85-90% relative humidity has been recommended for delaying ripening and loss of moisture. Controlled atmospheres low in oxygen and high in carbon dioxide are also effective in prolonging storage life. Experiments in the Sudan have shown that packing the fruits in polyethylene bags with an ethylene absorbent retards ripening and moisture loss and makes possible the shipping of the fruit by air freight to the United Kingdom.
In India, Mexican limes picked green were coated with wax emulsion containing the growth regulator, indole butyric acid, at 2,000 ppm and kept at room temperature of 65º to 85º F (18.33-29.44º C) and relative humidity of 60 to 90% for 17 days. On removal from storage, 75% of the fruits were marketable, while fruits left untreated and those coated with wax only were completely unmarketable.
A study in Trinidad demonstrated that Mexican limes treated with gibberellic acid, packaged in polyethylene bags to retain moisture, and stored at ambient temperature, remained in marketable condition for 65 days. Yellowing was retarded and there was no adverse effect on quality.
The Mexican lime is attacked by few pests. On the island of Niue, the most important enemy is snow scale, Unaspis citri, in prolonged droughts. Severe infestations cause dieback of branches; lighter attacks induce splitting of the bark which permits entry of other insects and fungi. The scale insect is transported from tree to tree by ants.
Withertip, or lime anthracnose, (Gleosporium limetticolum) is a serious affliction of the Mexican lime in Florida. Fusarium oxysporum causes wilt of seedlings in Florida greenhouses, induces twig dieback in India, and has been identified on Mexican lime grafted onto Rangpur mandarin lime in Brazil.
When the weather is too humid, the Mexican lime is prone to attack by the fungus, Elsinoe fawcetti, causing scab. It is also subject to algal disease and oil spotting can be severe. In Niue, the trees are often afflicted with collar rot, caused by Phytophthora sp. The fungus, Sphaeropsis tumefaciens, causing lime knot and witches broom, has destroyed many trees in Jamaica.
In 1982, a new strain of citrus canker, Xanthomonas campestris pv. citri, was found on 20,000 trees in the state of Colima, Mexico, in a 5-sq. mile (12.8 sq. km) area. Seedlings that had been shipped from this area were destroyed and the United States Department of Agriculture culture set up the requirement that all citrus imports from Mexico would have to be accompanied by a phytosanitary certificate. Canker is a common plague of limes in India and in 1960 the Horticultural Research Institute reported that Streptomycin sulfate at 500 ppm reduced the incidence by 34%.
The fruits are attacked by decay organisms in storage, principally Rhizopus nigricans and Penicillium spp.
The Mexican lime, because of its special bouquet and unique flavor, is ideal for serving in half as a garnish and flavoring for fish and meats, for adding zest to cold drinks, and for making limeade. In the Bahamas, fishermen and others who spend days in their sailboats, always have with them their bottles of homemade "old sour"lime juice and salt. Throughout Malaysia, this lime is grown mainly to flavor prepared foods and beverages. Commercially bottled lime juice is prized the world over for use in mixed alcoholic drinks. If whole limes are crushed by the screw-press process, the juice should be treated to remove some of the peel oil. It is calculated that 2,200 lbs (1 metric ton) of fruit should yield 1,058 lbs (480 kg) of juice.
Lime juice is made into sirup and sauce and pies similar to lemon pie. "Key Lime Pie" is a famous dish of the Florida Keys and southern Florida, but today is largely made from the frozen concentrate of the 'Tahiti' lime.
Mexican limes are often made into jam, jelly and marmalade. In Malaya, they are preserved in sirup. They are also pickled by first making 4 incisions in the apex, covering the fruits with salt, and later preserving them in vinegar. Before serving, the pickled fruits may be fried in coconut oil and sugar and then they are eaten as appetizers.
Pickling is done in India by quartering the fruits, layering the pieces with salt in glass or glazed clay jars, and placing in the sun for 3 to 4 days. The contents are stirred once a day. Green chili peppers, turmeric, ginger or other spices may be included at the outset. Coconut or other edible oil may be added last to enhance the keeping quality. Another method of pickling involves scraping the fruits, steeping them in lime juice, then salting and exposing to the sun.
Hard, dried limes are exported from India to Iraq for making a special beverage.
The oil derived from the Mexican lime is obtained by three different methods in the West Indies:
1) by hand-pressing in a copper bowl studded with spikes (which is called an écuelle). This method yields oil of the highest quality but it is produced in limited amounts. It is an important flavoring for hard candy.
2) by machine pressing, cold expression, of the oil from the spent half-shells after juice extraction, or simultaneously but with no contact with the juice.
3) by distillation from the oily pulp that rises to the top of tanks in which the washed, crushed fruits have been left to settle for 2 weeks to a month. This yields the highest percentage of oil. With terpenes and sesquiterpenes removed, it is extensively used in flavoring soft drinks, confectionery, ice cream, sherbet, and other food products. The settled juice is marketed for beverage manufacturing. The residue can be processed to recover citric acid.
The minced leaves are consumed in certain Javanese dishes. In the Philippines, the chopped peel is made into a sweetmeat with milk and coconut.
Food Value Per 100 g of Edible Portion*
|Vitamin A||0.003-0.040 mg|
|Riboflavin||0.011-0.02 3 mg|
|Ascorbic Acid||30.0-48.7 mg|
Juice: In the West Indies, the juice has been used in the process of dyeing leather. On the island of St. Johns, a cosmetic manufacturer produces a bottled Lime Moisture Lotion as a skin-conditioner.
Peel: The dehydrated peel is fed to cattle. In India, the powdered dried peel and the sludge remaining after clarifying lime juice are employed for cleaning metal.
Peel oil: The hand-pressed peel oil is mainly utilized in the perfume industry.
Twigs: In tropical Africa, lime twigs are popular chewsticks.
Medicinal Uses: Lime juice dispels the irritation and swelling of mosquito bites.
In Malaya, the juice is taken as a tonic and to relieve stomach ailments. Mixed with oil, it is given as a vermifuge. The pickled fruit, with other substances, is poulticed on the head to allay neuralgia. In India, the pickled fruit is eaten to relieve indigestion. The juice of the Mexican lime is regarded as an antiseptic, tonic, an antiscorbutic, an astringent, and as a diuretic in liver ailments, a digestive stimulant, a remedy for intestinal hemorrhage and hemorrhoids, heart palpitations, headache, convulsive cough, rheumatism, arthritis, falling hair, bad breath, and as a disinfectant for all kinds of ulcers when applied in a poultice.
The leaves are poulticed on skin diseases and on the abdomen of a new mother after childbirth. The leaves or an infusion of the crushed leaves may be applied to relieve headache. The leaf decoction is used as eye drops and to bathe a feverish patient; also as a mouth wash and gargle in cases of sore throat and thrush.
The root bark serves as a febrifuge, as does the seed kernel, ground and mixed with lime juice.
In addition, there are many purely superstitious uses of the lime in Malaya.