Skip to Content

Thorns, spines, and prickles

« Back to Glossary Index

**Function of Thorns, Spines, and Prickles**:
– Primary function is to deter herbivory in a mechanical form.
– Classified as physical defenses rather than chemical defenses.
– Some spines provide shading or insulation to plants, protecting them from extreme temperatures.
– Minimal impact on specialist pollinators crucial for plant reproduction.

**Definitions and Technical Distinctions**:
– Thorns and spines originate from shoots and leaves, respectively, with vascular bundles inside.
– Prickles lack vascular bundles, making them easier to remove.
– Thorns are modified stems emerging from buds.
– Distinction based on the presence of vascular tissue.
– Spinose processes categorized by vascular tissue presence.

– Modified branches or stems, either simple or branched.
– Examples include Citrus thorn and Gymnosporia buxifolia thorn.
– Carissa bispinosa exhibits branched thorns.
– Thorns can be smooth and featureless.
– Arise from axillary buds or nodes.

– Modified leaves, stipules, or leaf parts, often containing vascular tissue.
– Cacti are known for dense spine coverings.
– Some cacti have glochids, smaller spines with barbs.
– Fouquieria splendens develops spines from leaf petioles.

**Prickles and Other Structures**:
– Comparable to coarse hairs, extensions of cortex and epidermis.
– Prickles’ positioning appears random compared to thorns and spines.
– Spinose teeth, spinose apical processes, and trichomes are similar structures.
– Trichomes are smaller outgrowths of epidermal tissue, effective against small insects.
– Some roots transform into spines for defense.

In plant morphology, thorns, spines, and prickles, and in general spinose structures (sometimes called spinose teeth or spinose apical processes), are hard, rigid extensions or modifications of leaves, roots, stems, or buds with sharp, stiff ends, and generally serve the same function: physically defending plants against herbivory.

Prickles on a blackberry branch
« Back to Glossary Index