Of all the weird citruses available, this is one of the strangest.
Makrut lime, Citrus hystrix, is not grown for its ugly wrinkled fruit. The rind and the juice are only rarely used for culinary or medicinal purposes. The important part of makrut lime is the aromatic foliage, particularly the modified petiole "wings" that look like leaves. Fresh or dried, they are popular in the cuisine of Southeast Asia.
Mature trees can eventually reach second story eaves, but are usually kept significantly lower. They are so shrubby that even large trees should have plenty of foliage within easy reach from the ground. Once a tree gets overgrown, it is not as easily pruned lower as some other citrus trees are. Pruning stimulates vigorously long and arching stems, rather than more desirable fluffy growth.
The winged petioles are almost as long and wide as the actual leaves are. In fact, they look just like the leaves, making them look like double leaves. Although the petiole wings separated from the petiole are supposedly the most aromatic parts, leaves are useful, too. The hard fruits are about as big as golf balls and are the same rich green as the foliage, until they ripen to a light yellow. -- Tony Tomeo