The Meyer lemon tree, Citrus × meyeri, is a popular choice for home gardeners due to its desirable fruit and small stature. This citrus variety is a natural hybrid, thought to be a cross between a true lemon and either a mandarin orange or a pomelo. The resulting fruit is less acidic and sweeter than common lemons, featuring a thin rind that ripens to a deep yellow-orange color. Known for its compact, shrubby growth habit, the tree is often grown in containers, making it an attractive and productive addition to patios and backyards.
The Presence of Thorns on Meyer Lemons
Meyer lemon trees do have thorns, though their severity and number depend heavily on the specific cultivar and the age of the wood. Standard Meyer lemon varieties and trees grown from seed typically display small, sharp thorns. These thorns are less robust and numerous than the larger thorns found on some true lemon varieties. They are most often located along young, vigorous growth, particularly near the leaf axils.
Thorns can be a source of confusion for many gardeners, especially since most trees sold today are the ‘Improved Meyer’ lemon. This cultivar was selected to be nearly thornless, particularly on mature wood. This reduced thorn development leads to the incorrect belief that the species is naturally thorn-free. If a Meyer lemon tree is grafted, large, thorny shoots below the graft union are likely growth from the rootstock, not the Meyer lemon itself. Small, sharp thorns can still appear on new growth, even on the ‘Improved Meyer’ cultivar.
The Biological Role of Citrus Thorns
Thorns in citrus are an ancient evolutionary adaptation, classified botanically as modified stems. These sharp structures developed primarily as a physical defense mechanism to protect the plant from browsing herbivores. Thorns deter animals from consuming the tender, nutrient-rich leaves and growing tips. Conserving this new growth is crucial for the tree’s survival and its ability to photosynthesize and produce fruit.
Thorn development is more pronounced on juvenile wood because the younger plant is more vulnerable to damage. As the tree matures and the wood hardens, the need for physical defense lessens, and the thorns on older wood may become dull or disappear. The thorn itself arises from stem cells that undergo a programmed arrest, stopping development before forming a full branch. This genetic mechanism explains why a small, sharp point forms instead of a leafy side shoot.
Practical Management and Variation
Managing the few thorns on a Meyer lemon is a simple matter of safety and maintenance for the home gardener. When pruning or harvesting fruit, wearing sturdy garden gloves helps prevent injury from the small, sharp points. Any large or bothersome thorns can be clipped off using clean, sharp pruning shears without harming the tree. This is often done for branches at eye level or near high-traffic areas.
Pruning is also advisable if extremely thorny branches appear below the graft line, as these are typically unproductive rootstock growth that should be removed at the trunk. The ‘Improved Meyer’ lemon is the preferred choice for most homeowners because it was selected to be nearly thornless. This cultivar maintains the desirable fruit quality while minimizing the tree’s natural defensive structures. By choosing this common nursery variety, the issue of managing numerous or aggressive thorns is largely mitigated.