Canotia holacantha, of the family Celastraceae, has ascending green thorns and rushlike green branches; it bears five-petaled flowers and oval, brown, one- or two-seeded capsules.
It's a hypnotic afternoon of riding between the big mesas, up red dunes, across black gravel washes, along yellow valleys dotted with green thorns.
Koeberlinia spinosa, the only species of the family Koeberliniaceae, with green thorns at right angles to the branches, produces small, four-petaled, greenish flowers and clusters of black berries.
The stems themselves are green, and the thorns are substantial, resembling rose thorns.
Yellow-hammers, a stray wagtail, three or four pairs of chaffinches, a titmouse, most of them chirping or singing, and then - the sun shooting a beam of warm light on to the small green shoots of the thorn and the straggling bramble - all gave us a promise, if no more, of spring.
This marks an extraordinary shift for Zhang Yimou, who, in his greener days, was a thorn for the Chinese authorities.
Even our shelter from a ferocious cloudburst, an emerald green canopy of enormous, thorn-spiked gunnera leaves, felt lifted from a storybook.
"I think he is wrong on both counts," said Mr. Mastro, a longtime thorn in Mr. Green's side.
Mr. Leff and Mr. Baptist said anyone finding this weed, which has a green triangular leaf and sharp thorn on the stem of the vine, should pull it out of the ground as quickly as possible.
