Meyer lemon trees do have thorns, though they are generally smaller, softer, and less numerous than the thorns on standard lemon varieties like Eureka or Lisbon. A mature, well-maintained Meyer lemon may sport only short, stubby spikes along its branches, while a young or stressed tree can produce surprisingly sharp ones. The reason traces back to what a Meyer lemon actually is: not a pure lemon, but a hybrid whose parentage includes sweeter, less aggressive citrus relatives.
What Meyer Lemon Thorns Look Like
If you have grown a Eureka lemon, you know the type of thorn that can puncture a gardening glove. Meyer lemon thorns are a different animal. They tend to be shorter, sometimes only a centimeter or two long, and they are often blunter at the tip. On a healthy, mature tree that gets regular pruning, you may barely notice them. Some growers describe them as “nubbins” rather than true thorns.
That said, younger Meyer lemon trees and vigorous new shoots can produce thorns that are noticeably longer and sharper. This is not unusual for citrus in general. Juvenile wood and fast-growing water sprouts tend to be thorniest, regardless of the variety. As a Meyer lemon settles into maturity and begins flowering and fruiting regularly, thorn production usually decreases on its own.
Why Citrus Trees Grow Thorns in the First Place
Thorns on citrus are not random growths. In botanical terms, citrus thorns are modified axillary shoots: they begin as buds in the angle between a leaf and a stem, start growing like a normal branch, and then stop, hardening into a sharp point. These structures contain internal vascular tissue with fully developed wood, which is what makes them rigid and tough rather than flimsy.
The leading explanation for why they exist is defense against herbivory. Wild citrus ancestors evolved in Southeast Asian forests where browsing animals posed a constant threat to young growth. Sharp thorns discourage animals from stripping leaves and tender shoots. The fact that thorn-bearing species appear across many unrelated plant families suggests that thorns have evolved independently multiple times as a convergent defensive strategy.1Cell Press (Current Biology). Mechanisms of Thorn Identity and Stem Cell Regulation in Citrus In citrus specifically, thorns arise from meristematic tissues in leaf axils, representing a kind of organ-level shape-shifting where a potential branch becomes a weapon instead.2PubMed Central. Structural innovation under environmental pressure: the evolutionary origins and regulatory mechanisms of thorns
This matters for understanding Meyer lemons because thorniness is, at root, a deeply inherited citrus trait. Even heavily domesticated varieties retain it to some degree. The question is not really whether a citrus tree will have thorns but how many and how big.
How Meyer Lemon Parentage Affects Thorniness
Meyer lemons are not true lemons. Genetic analysis has shown that while standard yellow lemons (like Eureka and Lisbon) arose from a cross between citron and sour orange, the Meyer lemon came from a different combination: citron crossed with a mandarin-pomelo hybrid.3Oxford Academic (Annals of Botany). Phylogenetic origin of limes and lemons revealed by cytoplasmic and nuclear markers That mandarin-pomelo ancestry is what gives Meyer lemons their rounder shape, thinner skin, sweeter flavor, and darker orange-yellow color compared to grocery-store lemons.
It also helps explain the reduced thorniness. Citron, one of the most ancient citrus species, is famously thorny. Standard lemons inherited a heavy dose of citron character. Meyer lemons inherited citron traits too, but the mandarin and pomelo in their background diluted some of that thorniness. Mandarins and pomelos vary in their own thorn production, but many cultivated mandarin varieties are relatively smooth-branched. The result is a tree that still makes thorns but produces fewer, smaller ones than its pure-lemon cousins.
Young Trees Versus Mature Trees
One of the most common surprises for new Meyer lemon growers is how thorny a young tree can be. You may have bought it expecting a nearly thornless experience and found sharp spikes all over the first year’s growth. This is normal, and it usually improves.
Citrus trees go through a juvenile phase that can last several years. During this phase, vegetative growth is prioritized over flowering and fruiting, and the tree invests heavily in defensive structures. Thorns tend to be longest and most abundant during this period. As the tree transitions to reproductive maturity, the balance shifts. Branches that are producing flowers and fruit tend to be less thorny than purely vegetative ones. For a container-grown Meyer lemon, this transition can happen within two to three years; for a tree planted in the ground, it may take a bit longer depending on climate and care.
Fast-growing shoots that emerge from the interior of the canopy, sometimes called water sprouts, also tend to be extra thorny regardless of the tree’s age. These vigorous, upright shoots are the tree reverting to a more juvenile growth pattern, and they often carry the largest thorns on the tree.
Watch for Rootstock Suckers
Most Meyer lemon trees sold at nurseries are grafted. The top of the tree (the scion) is Meyer lemon, but the roots and a few inches of trunk belong to a different citrus variety chosen for disease resistance, cold tolerance, or vigor. Common rootstocks include trifoliate orange, Volkamer lemon, and various citrange hybrids. Many of these rootstocks are extremely thorny.
If you notice aggressive, extra-thorny growth emerging from below the graft union, the swollen knob visible near the base of the trunk, that growth is coming from the rootstock, not the Meyer lemon. These suckers should be removed immediately. Left unchecked, rootstock growth can outcompete the Meyer scion, eventually taking over the tree. The fruit produced by rootstock branches will not be Meyer lemons and is usually inedible.
The graft union is typically a few inches above the soil line, though on some dwarf trees it may be higher. If the thorny growth originates below that line, it is almost certainly rootstock. If it comes from above, it is your Meyer lemon going through normal thorny growth, most likely from a water sprout.
Pruning and Managing Thorns
You can safely prune thorns off a Meyer lemon tree without harming it. There is no evidence that removing thorns reduces fruit production or tree health. Many commercial citrus growers remove or break off thorns during routine canopy management, in part because thorns damage fruit. When wind moves branches, thorns scratch and puncture nearby fruit, creating cosmetic blemishes called wind scars. Research on citrus rind blemishes found a clear link between wind exposure and scarring severity, with blemishes appearing almost entirely within the first twelve weeks after petal fall when fruit skin is most vulnerable.4Elsevier / Scientia Horticulturae. Rind blemish of citrus. I. Initiation and development For a backyard grower, this means that thorns near developing fruit clusters are worth snipping.
The simplest approach is to clip thorns with sharp pruning shears or snips during your regular pruning sessions. You can also remove entire water sprouts, which eliminates the thorniest growth while opening up the canopy to light and air. Wear thick leather gloves when working inside the canopy, even on a relatively tame Meyer lemon. A thorn you did not see can still draw blood.
Stress, Nutrients, and Thorn Size
Environmental conditions can influence how aggressively a Meyer lemon produces thorns. A tree under stress may put more energy into defensive structures. One area where research has documented this involves nutrient imbalances. A study on Kinnow mandarin, a related citrus type, found that excess iron and zinc in the growing medium led to abnormal growth patterns including enlarged thorns and excessive water sprouts.5Scientific Reports. Effect of iron-zinc imbalance on morphophysiology and nutrient homeostasis of Kinnow mandarin (Citrus reticulata Blanco) under water-deficit While that study focused on mandarin under water-deficit conditions, the principle is relevant to Meyer lemons: if your tree is producing unusually large or numerous thorns, nutrient imbalance or other stress could be a factor.
Drought stress, root restriction in containers that are too small, and sudden shifts in light exposure can also push a tree toward more vigorous vegetative growth and, with it, more thorns. Keeping a Meyer lemon on a consistent watering schedule, in an appropriately sized container (if potted), and with balanced citrus fertilizer helps keep thorn production at the milder end of the spectrum.
The Improved Meyer Lemon
Almost every Meyer lemon tree sold in the United States today is technically the “Improved Meyer” lemon, a virus-free selection introduced by the University of California in the 1970s. The original Meyer lemon, brought to the U.S. from China in 1908 by Frank Meyer, was found to be a symptomless carrier of the citrus tristeza virus. Because it could spread the virus to other citrus trees without showing symptoms itself, the original Meyer was essentially banned from commercial production. The Improved Meyer was selected from virus-free budwood and is genetically the same tree minus the pathogen.
In terms of thorns, the Improved Meyer behaves the same as the original. The virus-free status does not change the tree’s growth habit, thorn production, or fruit characteristics. If you buy a “Meyer lemon” from a U.S. nursery, you are getting the Improved version, and it will have the same pattern of modest thorns described throughout this article.
The Genetics Behind Whether a Thorn Grows or Stops
Research on citrus has uncovered the molecular machinery that determines whether an axillary bud becomes a thorn or continues growing as a branch. Scientists identified two genes, called THORN IDENTITY1 and THORN IDENTITY2, that act as a kind of stop signal for the meristem (the cluster of dividing cells at the tip of a shoot). When these genes are active, the stem cells in the bud stop dividing and the growing tip hardens into a thorn. When researchers disrupted these genes, the stem cells kept dividing and the would-be thorn grew out as a normal branch instead.6PubMed Central. Reprogramming of Stem Cell Activity to Convert Thorns into Branches
This is a genuinely interesting finding because it means thorniness in citrus is not just about having more or fewer buds; it is about whether each individual bud receives the chemical signal to stop growing. Varieties like Meyer lemon, where the thorns are shorter and less frequent, may have subtly different regulation of these genes compared to highly thorny varieties like citron or trifoliate orange. Breeding programs that aim for thornless citrus are increasingly interested in this pathway, though a commercially available thornless Meyer lemon does not yet exist.
How Meyer Lemons Compare to Other Common Varieties
If you are choosing a lemon tree for a patio or backyard and thorns are a concern, it helps to know where Meyer falls on the spectrum. Lisbon lemons are among the thorniest of the widely available varieties; their thorns can be long, stiff, and plentiful, especially on interior branches. Eureka lemons are somewhat less thorny than Lisbon but still produce enough to be a nuisance during harvest. Meyer lemons sit at the milder end, with shorter, fewer thorns that many growers find manageable even without dedicated thorn removal.
Among other citrus types, mandarins and sweet oranges are generally less thorny still, and some modern mandarin cultivars are nearly thornless. At the other extreme, trifoliate orange and many lime varieties produce large, fierce thorns that make ungloved handling dangerous. If you are already comfortable with standard citrus care and not expecting a completely smooth tree, a Meyer lemon’s thorns are unlikely to bother you much.
Container Growing and Indoor Thorns
Meyer lemons are one of the most popular citrus trees for container growing and indoor cultivation, especially in climates too cold for year-round outdoor citrus. When grown in pots, these trees stay smaller and are pruned more aggressively, both of which tend to reduce thorn issues. A well-pruned container Meyer lemon, kept to three or four feet tall, may have only a handful of visible thorns at any given time.
Indoor trees do sometimes produce surprising bursts of thorny growth after being moved to a new location, repotted, or subjected to a change in light. This is the tree responding to stress by pushing out vigorous vegetative growth. The thorns on these new shoots may be longer than anything else on the tree. Give the tree time to adjust, and prune the water sprouts if they are detracting from the tree’s shape. The subsequent growth will usually be calmer.
For households with young children or pets, the thorns on a container Meyer lemon are worth taking seriously even though they are smaller than those on other citrus. Placing the tree where it will not be bumped into or grabbed, and clipping thorns on branches at child or pet height, are simple precautions that make coexistence easier.