Accession Count: 1
Common Name:
Key Lime
Family Name:
Rutaceae
Botanical Name:
Citrus aurantiifolia
Sub Species:
Variety:
Forma:
Cultivar:
Characteristics:
Citrus aurantiifolia, also known as key lime, is considered a small vigorous tree or large shrub. It may be multi-stemmed with densely packed slender, twisting and spreading branches. These branches are armed with numerous sharp spines that measure up to ⅜ inch long (1,2,3,4,5). It grows in tropical and warm subtropical regions, up to elevations of approximately 4000 feet. Reaching heights between 6 and 13 feet tall, it may exhibit a rounded umbrella, or vase-like form, covered in smooth dark brown bark (1,2,3,6,7). The plant is covered with glossy elliptic to oblong evergreen leaves, similar to orange (Citrus aurantium) leaves. Hence its specific epithet, aurantiifolia, which is formed from the genitive of the Latin noun aurantium, meaning “of orange,” and folia, which means “leaves” (6). The leaves have crenulated margins and are leathery in texture. The leaves are rounded at the base with narrowly-winged petioles and measuring between 1½ -4 inches in length by ¾-2¾ inches wide (3,4,6,7,8,9). When young, its leaves are light purplish in color, maturing to dark green above and paler green beneath (3,4). The leaves are distinctively aromatic when crushed (3,4). Showy flowers, purple-tinged when new and pale pink or white when mature, appear in springtime and late summer in axillary racemes composed of 1-7 flowers per raceme; they may be fragrant or unscented (3,4,7,8,9,). The flowers, which can measure up to 2 inches in diameter, are perfect (having both male and female parts), with 20-25 white stamens with yellow anthers, and have 4-6 petals measuring ¼ - ½ inches long (3,6,7,9). Small, globose or oval-shaped fruits, 1-2 inches in diameter, are borne singly or in clusters of 2 or 3 (or more) at the branch tips (1,3,5). Fruits are usually green when picked and greenish-yellow to yellow when ripe. They have a thin smooth peel, which commonly shows blotchy brown spots, and frequently have a small nipple at the apex (1,3,6,10). The aromatic greenish-yellow pulp inside is very juicy and highly acidic. It is divided into 10-12 segments with as many as 15 seeds, which are plump, smooth, oval-shaped, and pale (2,4). It is estimated that a metric ton of fruit (2200 pounds) yields 1058 pounds of juice (1,3). Of the two limes commonly available commercially today—the key lime and the Persian lime (Citrus X latifolia)—the key lime is smaller, more aromatic and more acidic; it also has more seeds, a thinner peel, and a more tart, even bitter, flavor (1,6,10,11). Citrus aurantiifolia freely hybridizes with other citrus or related species to produce a variety of hybrid fruits, such a lemonime (lime x lemon) and limequats (lime x kumquat) (9).
Compound:
Cit aur
Geographic Origin:
Southeast Asia
Ecozone Origin:
Indomalaya
Biome Origin:
Natural History:
Citrus aurantiifolia is believed to be a tri-hybrid intergeneric cross (a hybrid of three different parental species with at least one parent from a different genus than the others) involving Citrus medica (citron), Citrus grandis (pummelo) and a Microcitrus species (12). The plant is likely to have originated in southeastern Asia, probably Indonesia and Malaysia. It may also have had native populations in eastern and northeastern India, northern Myanmar and southwestern China (2,6). It is thought to have been brought by Arab traders to North Africa and the Middle East during the 10th century (1). From here it was probably carried by the Crusaders back to Europe where it was cultivated by the 13th century (1,3). It was likely brought as well to the Iberian peninsula by the Moors, whence it was carried to the New World (2, 3). There are reports that seeds were brought to the Americas as early as 1493, during Columbus’ second journey to the New World (1). The plant readily spread and naturalized throughout the tropical regions of the New World (2,3,6). The term “limey,” often used in derogative way to denote British people, stems from the British custom during the early 19th century of carrying limes on the ships of the Royal Navy to make food and drink more palatable for the sailors and, inadvertently, to help prevent scurvy (Some sources, however, say that it was actually lemon, not lime, juice that was carried on the ships [13]) (9). By the 19th century the plant was cultivated commercially in Florida, including plantings in the Florida Keys, hence its common name in English (2,3,6,10). The 1926 Miami hurricane, however, destroyed the industry in Florida, relegating the plant there to the status of a “dooryard” fruit (3,6). Although a public relations effort in the 1950s to renew interest in the plant succeeded in getting nurseries to propagate it for sale and may be the reason why the common English name is still used, there is presently little key lime production in Florida (2,3,6). Today Citrus aurantiifolia is grown as a commercial crop in India, Egypt, Mexico, the West Indies, and in the tropical regions of the Americas and the Old Word (3).
Cultivation Notes:
In warm climates, Citrus aurantiifolia is good choice for a landscape plant with the added benefit of fruit production. It is typically propagated from seeds because it is true-to-type due to a high degree of polyembryony (multiple maternal embryos in one seed) found in the species (2,4,9). For this same reason there are few varieties of the species, some of which are thornless but typically produce less fruit (2). The plant can also by propagated by cuttings, budding, grafting, or air-layering (2,3,6). It should be planted in the warmest location possible, protected from cold wind and in full sun, as it does not tolerate shade (2,6,14). It grows best in warm, moist regions that receive at least 25 to 40 inches of rainfall annually (8). Citrus aurantiifolia is the most frost-sensitive citrus and in regions with cold winters care should be taken to avoid freezing temperatures, as damage to the leaves and flowers occurs between 32° and 30°F and wood damage and death occurs at temperatures below 29° (1,2,6). In cooler climates, plants can be grown in large containers which allow them to be moved inside during cold spells (14). Seedlings will begin to flower and fruit after 3 to 6 years and be in full production after 8 or 10 years (3,6). It does not require cross-pollination to set fruit (2). The fruit generally takes between 5 and 6 (sometimes up to 9) months from flower to harvest and should be gathered when the fruit mature, that is, when it has a yellow peel (2,3,6,9,). A vigorous, mature tree may produce up to 50 pounds of fruit a year (2). In the proper environment, the plant is often ever-bearing, although there is usually a primary season in May/June and a second season in November/December (1,3). The plant grows best in light to medium textured soils that are aerated and have good drainage. Although it also does well in the rocky, calcareous soil of south Florida and in the sandy or gravelly soil of Hawaii (2,3,15). The plant will not do well in heavy clays or soils that drain poorly and it should not be planted in areas where the water table is high as the plant does not tolerate standing water or flooding (2,14,15). The plant is sensitive to high salinity and prefers a pH range of 5 to 8 (2,15). It is very drought tolerant and once established, a mature tree will not need to be watered frequently and overwatering may cause fungal infections and decline (2,3). When planting a plant purchased from a nursery, plant it at least at the level of the surrounding yard, if not above it; planting it in a basin or depression below the level of the surrounding yard will cause excess water to accumulate and will cause the tree to contract foot rot (14). Mulching is optional, but should be kept at least 8-12 inches from the trunk to avoid trunk rot (2,14). Key lime should be fertilized sparingly (2). In general the plant will need little pruning: only to shape it, remove dead wood, limit plant size, or thin fruit (2,3). If desired, the plant can also be espaliered or hedged (7).
Ethnobotany:
Citrus aurantiifolia is a very valuable plant and is used in a variety of ways. The fruit is the most popular part of the plant and is often sold fresh (6). It is a good source of vitamins A and C, contains few calories, little sodium and no cholesterol (1,2,6). It is often used to prepare or accompany beverages or as a garnish squeezed over fish, meat, and other foods (2,3,6,9,14,16). Lime juice, an important export product for many countries, is made into sauces, marinades, syrups, jams and jellies, and is used in hot and spicy dishes (1,3,6,9). Key limes provide flavoring for desserts such as sherbets, sorbets, ice creams, and the famous key lime pie (although Persian or Tahitian limes are more commonly used for the flavoring today)(1,3,6,10,11,16). Lime juice can be employed as an antioxidant when squeezed over fresh-cut fruit to prevent its browning (1). The zest from the peel is added as flavoring in a variety of dishes. The oil, also derived from the peel, is used to flavor many products such as soft drinks, ice creams and other products (1,3). In the Philippines, the peel is chopped and mixed with milk and coconut to make a sweetmeat (3). Limes are often pickled and preserved whole in a variety ways (1,3,9). Dried, hard limes are sometimes used to make a special drink in Iraq (3). In the Middle East, limes are boiled in brine and then dried to make black (or dried) lime, a common condiment and ingredient in Middle Eastern cooking (6.). The aromatic leaves are used as a flavoring and seasoning in Asian dishes and are sometimes boiled to make a tea that is taken in place of coffee (3,6,16). In addition to being used as a food, the plant is reported to have many medicinal applications. Lime juice is a natural remedy for relief of irritation caused by mosquito bites (3,6). In traditional medicine, the juice is taken to relieve a variety of stomach and intestinal conditions (3,6). It is taken as a vermifuge when mixed with oil and as a diuretic for liver ailments (3). The juice is also used to treat sores, fevers, chest colds, convulsive coughs, headache, heart palpitations, hemorrhoids, snakebite, hair loss, bad breath, dandruff, and crab-lice (3,6,16). It has been used as a tonic, astringent, and antiseptic (3,6). The leaves can be made into a poultice or infusion used to treat skin diseases, to ease the abdomen of a new mother after childbirth, to relieve headaches, to rinse the eyes, to treat colds, or to use as a gargle for sore throat or other mouth conditions (3,6). A decoction of the roots is used as a vermifuge, contraceptive, and abortifacient. It is used to treat venereal disease and fever (3,6). Ground seed kernel, mixed with lime juice, also helps alleviate fever (3). Many folk medicine uses may be associated with the belief that limes dispel evil spirits (9). The Lime juice and oil pressed from the peel are also used extensively in cosmetics and skin conditioners (2,3). The essential oil pressed from the peel is reported to bring many health benefits (17). In the West Indies, the juice is used in dyeing leather (3). The dehydrated peel is sometimes fed to cattle (3). In the Pacific islands, flexible saplings from the plant are bent and used as frames for fish nets and the wood is used as handles for adzes and attachments on canoes (16).
Height:
11 - 15 feet
Width:
6 - 10 feet
Growth Rate:
Moderate Growing
Grow Season:
Spring
Flower Season:
Summer
Color:
White
Function:
Accent
Spread:
Non-spreading
Allergen:
Allergenic
Invasive:
Benign
Toxicity:
Benign
Hardy:
Tender
Water Use:
High Water Use
Citations:
1. Nolte, K. “Mexican Lime.” University of Arizona, College of Agriculture and Life Sciences. Accessed May 24, 2015.
2. Crane, J. “Key Lime Growing in the Florida Home Landscape.” University of Florida IFAS Extension. Accessed May 24, 2015.
3. Morton, J. (1987), “Citrus aurantifolia Swingle.” In Fruits of Warm Climates (Center for New Crops & Crop Products, Purdue University. Accessed May 24, 2015.
4. “Mexican Lime.” University of California Riverside, College of Natural and Agricultural
Sciences. Accessed May 24, 2015.
5. “Citrus aurantifolia.” Food and Agriculture Organization of the UN. Accessed May 24, 2015.
6. “Citrus aurantiifolia (Christm.) Swingle (pro. sp.).” Encyclopedia of Life. Accessed May 24, 2015.
7. “Key Lime.” California Polytechnic State University, Urban Forest Ecosystems Institute. Accessed May 24, 2015.
8. “Citrus aurantiifolia.” Pacific Island Ecosystems at Risk (PIER). Accessed May 24, 2015.
9. “Citrus aurantiifolia (lime).” Invasive Species Compendium, CABI. Accessed May 24, 2015.
10. “Citrus aurantiifolia (Christm.). Swin…” Global Biodiversity Information Facility
11. “Citrus aurantiifolia.” Citrus Genome Database. Accessed May 24, 2015.
12. Moore, G.A. (2001), “Oranges and lemons: clues to the taxonomy of Citrus from molecular markers.” Trends in Genetics 17: 536-540.
13. “Morton, J. (1987), “Lemon.” In Fruits of Warm Climates (Center for New
Crops & Crop Products, Purdue University. Accessed May 24, 2015.
14. Sauls, J. (1998) “Home Fruit Production – Limes.” Texas Citrus and Subtropical Fruits, Horticultural Sciences Department, Texas A&M University: Accessed May 24, 2015.
15. “Crop Water Information: Citrus.” Food and Agriculture Organization of the United Nations. Accessed May 24, 2015.
16. “Citrus aurantifolia – Rutaceae.” People and Plants of Micronesia. Accessed May 24, 2015.
17. “Health Benefits of Lime Essential Oil.” Organic Facts. Accessed May 24, 2015.
