Limes grow on trees, although their relatively small size sometimes causes them to be mistaken for bushes or shrubs. The lime is the highly acidic, small, round fruit of a plant belonging to the Citrus genus, which originated in tropical and subtropical regions of Southeast Asia. Cultivated globally, the fruit is prized for its tart juice and fragrant zest, making it a popular ingredient in food and beverages.
Lime Trees: Botanical Classification and Structure
Lime plants are classified botanically as trees because they possess a single, woody main trunk and overall structure. The Citrus genus features evergreen plants with a distinct woody stem, separating them from the multiple, smaller, non-woody stems typical of true shrubs or bushes. Although many trees reach heights of fifty feet or more, lime trees are considered small trees.
The Key lime variety, for instance, typically grows to about 16 feet (5 meters) tall. It is often described as a “shrub-like tree” due to its dense, irregular branching and tendency to spread. However, the presence of a clearly defined main trunk, even if short, anchors its classification as a tree. Many lime varieties also possess short, stiff spines along their branches, a common characteristic of the Citrus genus.
Growth Habits and Popular Cultivars
Lime trees require warm, tropical to subtropical conditions, as they are highly sensitive to cold temperatures and frost. They thrive in well-drained, slightly acidic soil and need consistent moisture to support their evergreen foliage and year-round fruiting cycles. While they require significant sunlight exposure, these trees do not tolerate standing water, which can lead to root rot.
The two most common varieties encountered commercially are the Key lime and the Persian lime, each with distinct growth habits. The Key lime (Citrus aurantiifolia) is known for its compact, thorny, and densely branched structure, producing small, seedy, and highly aromatic fruits. Conversely, the Persian lime (Citrus latifolia), the large, seedless lime found in most grocery stores, is a more vigorous and robust tree.
The Persian lime is often a hybrid developed from the Key lime and is less thorny, growing up to 20 feet in favorable conditions. This variety’s thick, waxy skin makes it ideal for commercial shipping, reinforcing its dominance in global markets. Both cultivars are woody, evergreen perennials, though they may appear more like a large shrub when grown in containers or pruned heavily.