-- S. setigeroides (seh-tidge-ger-OID-ees) and S. novomexicanum (novo-Mexi-can-um) both were classified previously as varieties of S. heterodoxum. The first species is a widespread weed from northern Chihuahua and west Texas to central Arizona and New Mexico. The other is found only in northern New Mexico. The Red List categorizes both as species of "least concern," meaning they are neither threatened nor endangered.
Hunting for a Suspected New and Endangered Species
Newly identified S. cordicitum grows only about 14 inches tall. The stems and leaf stalks have very short hairs as well as prickles or spines about one-fifth-inch long, "but that's still long enough to stick you," Bohs says. The leaves have three or four lobes on each side. Prickles also cover the flower clusters, which have five to eight flowers.
"Prickles are all over this sucker," Bohs says.
The first specimen of S. cordicitum was collected in October 1974 on U.S. 166 about 30 miles west of Fort Davis, Texas. Then in September 1990, a Valentine resident named Howard Elder found the plant on his property. A botanist wrongly identified the plant as S. heterodoxum. It later was wrongly re-identified two more times: as S. davisense in 1997 and as a variety of S. grayi in 2006.
But Bohs and colleagues believed it was none of those species because its flower petals are white instead of yellow, and its flower stalks are longer and flowers are larger than closely related species. There also are differences from other species in leaf shape and in stem hairs.
Also, a study published in 2010 by Stern, Bohs and Utah postdoctoral researcher Terri Weese showed the plant's DNA differed from known species. And the plant is an annual, while related species are perennials.
So Bohs and colleagues decided to try to find more specimens. In 2010, Stern then a Utah gra
|Contact: Lee J. Siegel|
University of Utah