Tribulus terrestris
This is a weedy plant introduced from southern Africa. The spiny fruits, which are the origin of the common name "goats heads", can easily puncture tires.
A very small flowering plant on NM Hwy 159 west of Mogollon, Catron Co., NM, 16 Aug 2009.
A flower at Samalayuca Dunes, south of Juaréz, Chihuahua, Mexico, 5 Sep 2009.
Fruit near my apartment in Las Cruces, Doña Ana County, New Mexico, 22 Aug 2004.
Flowering stem near my apartment in Las Cruces, 22 Aug 2004.
A flower near my apartment in Las Cruces, 29 Sep 2004.