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Mimosa microphylla: Catclaw sensitive briar, Little-leaf mimosa, Littleleaf sensitive-briar
Fabaceae (Pea Family)
Native to U.S.
Weak, sprawling stems, up to 3 ft. long, are armed with hooked prickles. Bi-pinnately compound leaves, having an airy appearance. The leaflets are sensitive to the touch if one brushes against them or touches them, they immediately fold up against each other, suggesting the name sensitive briar. They also close at night and in cloudy weather. The fruit is a long, slender pod, densely covered with prickles.
These thumbnail size flowers I found in Herman Baker Park, Sherman, Texas, USA are ablaze with color dotting the ground.
Canon Powershot SX20 IS