Funastrum crispum
Funastrum crispum and Funastrum cynanchoides (sensu lato) are not terribly easily distinguished using available keys but readily distinct when seen in flower. Rather than list the various characters, I suggest simply comparing the photographs below with those for Funastrum crispum. In writing, the two can be confused; visually, they cannot.
Southern San Andres Mountains just west of the junction of Ash Canyon and Salt Canyon, Doña Ana County, New Mexico, 16 Jul 2013.
Somewhat immature flowers on the west side of the Sacramento Mountains southwest of Bent, Otero County, New Mexico, 9 Aug 2009.
A flowering stem on the west side of the Sacramento Mountains southwest of Bent, 9 Aug 2009.
A vegetative stem, twining away on the east side of the Big Burro Mountains, Grant County, New Mexico, 22 Sep 2007.
A cauline leaf on the east side of the Big Burro Mountains, 22 Sep 2007.