General · EdgepediaSeptember 17, 20266 min read

Latex

Latex is a sticky, often milky emulsion that exudes from specialized canals or cells of plants upon injury, distinct from ordinary sap in being more viscous and colloidal. It is produced by secretory structures called laticifers and occurs in roughly 10 percent of flowering plant species, with no known primary metabolic function; its best-supported role is defense against herbivorous insects¹. The word comes from Latin latex, -icis, meaning a fluid or juice².

Key fact	Detail
Definition	Sticky emulsion exuded on damage from specialized canals in about 10% of flowering plant species¹
Producing structures	Laticifers, secretory cells or interconnected cell systems permeating the plant body³
Chemistry	Mainly terpenes, plus rubber, mucilage, phenolic compounds, alkaloids, cardenolides, starch grains, and proteins such as cysteine proteases⁴
Richest families	Apocynaceae, Euphorbiaceae, Moraceae, and Papaveraceae³
Function	Defense against herbivores and pathogens, and wound healing; latex-deficient mutants are more susceptible to herbivores⁵
Industrial use	Hevea brasiliensis latex is the source of natural rubber, essentially polyisoprene⁶
Extent	Laticiferous species recorded in more than 40 phylogenetically distant families, predominantly in tropical regions⁷

Occurrence and distribution

A survey by the plant anatomist Katherine Esau, reported in a Durham thesis, counted latex in 12,500 species⁸. Latex-bearing plants appear across many families and growth forms, including herbaceous plants, lianas, shrubs, and trees⁶. Within a single laticiferous family the chemical composition varies, and even within a genus there are usually species with and without laticifers⁹.

The families with the highest numbers of latex-producing species are Apocynaceae, Euphorbiaceae, Moraceae, and Papaveraceae³. In Asteraceae, one of the largest plant families with 1,620 genera and over 23,000 species, about 1,800 species are latex-producing¹⁰.

Laticifers

Latex is produced by laticifers, secretory structures composed of single or interconnected cells that form systems permeating the entire plant body³. Their expansion into tube shapes occurs through two mechanisms, cell fusion and intrusive growth, and the extent of intrusive growth is still being investigated⁵. Recent evidence suggests that independent clusters of laticifers may arise in different organs and tissues of a plant and then hold distinct chemical and biochemical contents⁴.

A 2025 anatomical study of the subfamily Acalyphoideae overturned a long-standing assumption. Acalyphoideae had traditionally been distinguished from the rest of Euphorbiaceae by the absence of latex and laticifers, but analysis of 40 species in 10 genera found laticifers in all studied species, showing that these cells are present and common there and more widespread in Euphorbiaceae than previously known¹¹. Kew's family treatment still notes that Euphorbiaceae latex is white or yellowish to red and absent in Acalyphoideae¹².

Chemistry

All latices contain molecules in colloidal suspension, most often resins and hydrocarbons⁶. Although the latex of different species consists mainly of terpenes, it also contains rubber, mucilage, phenolic compounds, alkaloids, and cardenolides; carbohydrates such as starch grains are present, and proteins such as cysteine proteases are common in the latex of some species⁴.

Color varies widely. Most plant latex is whitish or cream colored, but bloodroot has deep orange-red latex and some other members of the poppy family have lemon-yellow latex¹³. Documented examples include milky white in the rubber tree (Hevea brasiliensis), pale yellow in Ficus septica, orange in Ficus benguetensis, and scarlet in the dragon's blood tree Croton lechleri¹⁴.

Defense against herbivores

Latex has been strongly implicated in defense against herbivorous insects¹. Mutant plants deficient in latex production show increased susceptibility to multiple herbivores, and metabolites and proteins concentrated in latex deter insect feeding in a variety of species, with proteases likely serving a general defensive role⁵.

Herbivores that feed on latex-bearing plants typically evade the fluid by severing the laticifers, feeding intercellularly, or through physiological adaptations¹. Convergent evolution appears to be widespread both in plants with latex and in the insects that exploit latex-bearing plants, and because latex shows phenotypic plasticity, heritability, and macroevolutionary lability, it serves as a model system for studying plant-herbivore interactions¹.

Coagulation speed is part of the defense. Species of Campanula coagulate their latex in 10 seconds or less, and a pressure-chamber test showed Campanula latex coagulating at 8 bar, a pressure at which coagulation in Ficus benjamina, described as having a mechanism similar to Hevea, has been reported to be impaired¹⁵.

Evolution and diversification

Because latex is a highly convergent trait, it has been hypothesized to have evolved independently several times as a defense system improving plant fitness in the presence of herbivores⁹. An earlier hypothesis held that latex and resin canals drove species diversification through escape-and-radiate coevolution, but a 2019 re-examination by Foisy and colleagues found no longer strong evidence that latex or resin canals are general, consistently replicable drivers of species diversity across plants, while confirming that both are potent defenses and model traits for studying plant-herbivore interactions¹⁶.

Uses

The dominant industrial use is natural rubber from Hevea brasiliensis, in whose latex rubber is present in the laticifer cytoplasm; the latex coagulates naturally on leaving the plant or by the addition of acid, and rubber itself is essentially polyisoprene⁶. Other latex plants are classified by their products: rubber (hevea, parthenium, landolphia), gutta-percha (Palaquium), balata (Mimusops), and alkaloids (poppy)⁶. Nearly chemical-free natural plant latex is also used in manufacturing natural latex mattresses, beauty application pads, and cushioning¹⁷, and medicinal plant latex is a reservoir of antimicrobial peptides, proteins, and enzymes for drug discovery¹⁰.

References

Topic: Encyclopedia › Life and health › Plants and algae › Seed plants › Other flowering plants › Rosids › Fabaceae: legumes and the pea family › Titles A to L › Titles Di to L

Initially written Sep 17, 2026 · Reviewed: Sep 19, 2026; Oct 21, 2026 · Edited: Oct 15, 2026; Oct 21, 2026 · Last review: Oct 21, 2026

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