Irritating

This is the leaf of the common nettle (Urtica dioica). If you come into contact too closely with this plant it will give you a very irritating and itchy rash.

Apparently stinging nettles “have many hollow stinging hairs called trichomes on the leaves and stems, which act like hypodermic needles, injecting histamine and other chemicals that produce a stinging sensation when contacted by humans and other animals.” [1]

The plant itself (inset) looks quite harmless and almost pretty with it’s dangling flowers. The macro version of the leaf shows those spikes (trichomes) just waiting to inject us and cause all the irritation we know as nettle rash, sending us searching out the antihistamine cream. Look at it large to see how deadly it is.

(1) Good old Uncle Wiki