Like the best of villains, Buffalobur Nightshade or Buffalo Burr (Solanum rostratum) is deceptively attractive. It has cheery yellow flowers and ornately-lobed dark green leaves similar to those of a watermelon plant.

But if you look a little bit closer, Buffalobur Nightshade's innately evil nature becomes apparent. Long, sharp thorns cover the stems and surround the flowers and even line the veins of the attractive leaves. Its yellow flowers are followed by wickedly spiny burrs that can become scattered about and are quite painful to step on.

The stout spines of Buffalobur Nightshade are not merely sharp, these spines are also covered with a substance that can cause intense, lingering pain in anyone stabbed by them. My dog Sammy stepped on a Buffalobur Nightshade burr, and my dad was poked in the hand while removing it. My dad said that it was very painful and the pain lasted for quite a while. Even after the burr had been removed, Sammy kept chewing and chewing at his poor foot, so he was obviously suffering from lingering pain from this evil plant as well.

However, the most dangerous characteristic of Buffalobur Nightshade is that it is poisonous. Buffalobur Nightshade, like other poisonous nightshades (Solanum spp.), contains the deadly glycoalkaloid solanine and other tropane alkaloids. Buffalobur Nightshade is also capable of accumulating excess nitrates in soils high in nitrogen, so it can cause nitrate poisoning in addition to solanine poisoning.

In addition to all of its other negative characteristics, Buffalobur Nightshade is not a well-behaved plant, instead it is a highly invasive, noxious weed. It thrives in the abused soil of overgrazed pastures, where it can poison cattle and render a pasture unusable unless control measures are taken.

I spotted these Buffalobur Nightshade plants growing at the edge of a cow pasture south of Tucson. These plants are currently in full bloom because of our summer monsoon rains. From now on when photographing summer wildflowers, I'll keep my dogs well away from these evil plants and their wicked burrs.