Family: Zygophyllaceae – Caltrop Family
Annual herbs laying flat on the ground; stems 0.4” to 4” (1 to 10 cm) long
Leaves: opposite; pinnately compound; has hairs
Flowers: 5 yellow petals; 5 sepals; stamens usually 10; petals 0.12” to 0.2” (3 to 5 mm) long
Blooms in Arches National Park: August, September, October, November
Location seen: entrance road and around Visitor Center buildings
Fruits: 2-spined nutlets; spines are horn-like
Pollinators: other genera in this family are pollinated by bees
Habitat in Arches National Park: disturbed areas and open sites
Other: The genus name, “Tribulus”, is Latin for "three-pointed, a caltrop," the shape of which is suggested by the three-pronged fruit, and referring to the caltrop, a military weapon, an iron ball with projecting spikes. The species name, “terrestris”, is Latin for "on land". Put together, the scientific name can translate to “tribulation of the earth” which refers to the fact that it is not native, spreads rapidly, and has very sharp seeds that can puncture feet or tires.
This is a non-native plant.