I was out botanizing a vacant lot just a few blocks down from my house recently when I came across a plant that is more than capable of defending itself from potential herbivores or the unwary naturalist. This is none other than Texas Bull-Nettle or Cnidoscolus texanus.
The white flowers are mostly harmless but the remainder of the plant is loaded with trouble. With other common names like Bull Nettle, Treadsoftly, and Mala Mujer (I get the direct translation of the Spanish but there must be some cultural context tacked onto this that I am ignorant of–Can anyone place this in the correct context?), there is no doubt that this plant means business.
These are herbaceous plants, about 80-100cm tall. An individual plant has separate male and female flowers together on the same inflorescence. I didn’t get any closer to this plant than I had to so can’t be for sure which sex these flowers are. The next photo reveals why I kept my distance from this plant.
Notice both the main stem and the stem branches. All are covered with hispid or bristly hairs. But these are not normal hairs; they are extremely painful, stinging hairs. The leaves are covered with the same stinging hairs as well. Here is how this plant defense mechanism works: If the foliage or stems are touched, the glass-like hairs break off in the skin (yours or a hapless four-legged fellow creature) and act like hypodermic needles. The “needles” release a toxin which causes an intense burning sensation. This effect is a type of allergic response known as contact urticaria and the reaction can last for several days.
The genus name Cnidoscolus says it all. The Greek cnide means nettle and scolopes means prickle or sting. From the flowering plant family Euphorbiaceae. A good plant species to know and respect!