The Mexican or key lime is a small tree or shrub that grows well in our area of South Texas, provided that we don't get a hard freeze during the winter. Temperatures dipping below 28 degrees can wreak havoc on this citrus. The tree can grow to about 12-15 feet tall and does best if planted in an area protected from northerly winds. If possible, try to plant it on the south side of a building, as close as practical, so that the building's radiant heat will protect it during a dip in the mercury. This type of citrus is heavily armed with abundant thorns, so one must take care when harvesting the fruit. In my opinion, the Mexican or key lime is the best tasting of all lime varieties.
Even though we consider it a Mexican lime, this citrus actually originates in India and Southeast Asia. Several years ago when I was in Thailand, I feasted daily on many wonderful Thai dishes and native fruits. A regularly served condiment with most meals was the same lime we enjoy here. Along with the lime wedges also came a tiny bowl of finely sliced chile piquin in fish sauce. I'm talking about the same little chiles that grow wild around here. I felt right at home! Marco Polo and his successors introduced and distributed many fruits and foods to various parts of the world during their travels. Hot peppers are a part of every culture in India, Southeast Asia, and China. These peppers were introduced from Mexico and Central America. I often wonder what Italians would be eating today if those explorers had not introduced them to noodles for pasta from China and tomatoes for sauce from Mexico. Did you know that flour tortillas were invented by German settlers in Mexico?
Getting back to our topic.... Botanically, this tree is known as Citrus aurantifolia. Everywhere in the world that it is grown, it is used as a food and as a medicine. In the Amazon basin the juice of the fruit is mixed with other herbs and used to treat measles. A decoction of the root taken once a day during menses is said to act as a contraceptive. The rind of the fruit is used as an anti-dandruff, anti-spasmodic, decongestant, and sedative. The flowers are used for cramps and enteritis. This species as well as other citrus are high in limonene, a bioflavonoid, ascorbic acid, and beta-carotene, all noted to prevent cancer.
The juice of the lime is a great disinfectant for skin sores and irritations. It is also used as a gargle when mixed with water. Lime juice is useful in treating liver disorders, rheumatism, or as an eye disinfectant (diluted with purified and sterile water). Some indigenous peoples in Mexico use this to treat the eyes of their newborn infants. The juice, when mixed with hot water, is used to treat diarrhea. When applied to the scalp, it is said to strengthen and firm up the hair.
In the traditional medicine of Mexico, the lime is used to treat nerve disorders, as an emmenagogue, as an contraceptive, for kidney stones, cuts, dog bites, insect bites, and scorpion stings. It is also used as an anti-parasitic, antiseptic, ophthalmic, hemostatic, hepatic, and as a capillary tonic. It is also used to treat digestive disorders such as heartburn, amoebas, gall bladder problems, dysentery, stomach ache, empacho, diabetes, conjunctivitis, typhoid, obesity, nausea, and vomiting. Respiratory applications include sore throat, flu, throat infection, cough, and colds. As a child, I was often given honey with lime for coughs.
Besides the fruit, all other parts of the tree are used for treating various conditions. The branches and leaves can be steeped or boiled and used as a bath or drunk as a tea to relax, to improve the appetite, and to dispel a bad or bitter taste in the mouth. The wood of the branches or the roots is boiled and taken to lose weight. The flowers are combined with banana (Musa acuminata) flowers as an infusion and taken daily to benefit the kidneys. The bark of the tree is combined with cinnamon and brewed into a tea and drunk warm to treat hoarseness.
If you are considering a citrus tree for your yard, I highly recommend the Mexican lime. They are available as young grafted trees at most local nurseries and garden centers, often times already bearing fruit. Since this lime is a clean species and not a hybrid, you can also plant the seeds from a lime and eventually end up with a true-to-form bearing lime tree, as I have done. The main advantage to a seedling tree over a grafted one is that if we ever experience a super-killer freeze as we have a few times over the last two decades, the tree will come back true, even if killed to ground level as all of mine have been. The main disadvantage is waiting out the juvenile factor, which in the case of C. aurantifolia is seven years before it begins to bloom and bear limes. I started my lime trees in 1976 when we lived in Houston.
Regardless of the type of tree you grow, I think you will enjoy the abundant and juicy limes that you harvest. If you want to experience them at their peak of flavor, bouquet, and juice content, do not pick them until they turn yellow and drop into your hand when you barely touch them. If your tree cranks out more fruit than you can use and all your friends quit coming by to visit you for fear that you will give them more limes, you can squeeze them and freeze the juice in ice trays for later use. Just be sure to store them in an air-tight container in the freezer to maintain quality. When our kids were little, we always had a gallon of limonada in the refrigerator to quench the thirst of our kids and all their friends. Every once in a while I can talk my wife into making a key lime pie. If you are trying to reduce your salt intake, try substituting a squeeze of lime for salt on your food. It is also great in soups, on rice dishes, barbecued chicken, carne asada, and of course, menudo! Almost any desert will take on a refreshing zest with a dash of lime. Please don't take my word for it. Give it a try on something weird and let me know.