Trichome
/ˈtraɪkoʊm/
Definition
Trichome refers to a small hair-like or scale-like outgrowth from a plant’s epidermis, the outer cell layer. It may be a single cell or many cells and can be nonglandular or glandular, meaning it may only provide physical coverage or also secrete substances such as oils or sticky compounds. Trichomes occur on leaves, stems, flowers, and fruits, where they can reduce water loss, reflect light, or help deter herbivores and pests.
Function in Plants
- Defense against herbivores: A trichome can make leaves and stems harder for insects and grazing animals to eat. Some forms are stiff or hooked, while glandular types release compounds that deter feeding or slow small pests.
- Water and heat regulation: Dense surface covering can reflect sunlight, reduce leaf temperature, and slow water loss by trapping a thin layer of still air. This can help plants cope with dry, windy, or high-light conditions.
- Protection from environmental stress: On young shoots, a trichome may shield delicate tissue from abrasion, excess ultraviolet light, or sudden drying. In some species, root forms also increase contact with soil and improve water and nutrient uptake.
- Useful identification feature: Botanists often compare presence, density, shape, and whether a trichome is glandular or non-glandular when identifying plants. These traits can help separate closely related species or describe cultivars accurately.
Related Terms
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Cuticle
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Leaf
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Gland
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Spine
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Areole
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Thorn
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