*Tribulus terrestris  Puncture Vine, Caltrop
EXOTIC ANNUAL.  Long creeping stems and shiny pinnate leaves lie flat on the ground.  Yellow flowers have five petals, five-lobed stigma.  Blooms all summer.  Hard star-shaped seedpods have sharp, penetrating spines.  Occasional in flat gravel washes, dirt roads, recently disturbed ground.
FAMILY:  Zygophyllaceae (Caltrop Family)