Plant hairs, also called trichomes, are like a smart botanical equivalent of mini, multi- talented octopus arms wielding an armoury of secret chemical and physical weapons and shields. These living cells read and respond to their environment.
Their various uses mean they may be branched, star-shaped, straight, barbed, curly, sticky or poisonous gland-tipped – or even umbrella-like, as in the incredible tree- dwelling bromeliads whose tiny trichomes open when it’s dry to reduce evaporation and close during rain to absorb water.
Those on roots help draw up minerals and water, while hooked stem, fruit and leaf hairs disperse seeds on passing animals. Some help capture prey in carnivorous sundews, others deter the tiniest and largest insect grazers with physical barriers and protect against strong light, cold, wind and water loss.
The nettle family’s needle-like hairs are hollow and loaded with toxic histamine, serotonin and formic acid capable of causing pain, itching and inflammation when a fragile silica tip pierces skin. Discover if dock leaves really do help nettle stings
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