rattail cactus

a small, often cultivated cactus (Aporocactus flagelliformis) with weak, cylindrical, creeping or drooping stems, native to Mexico and Central America

See rattail cactus in American Heritage Dictionary 4

or rat's tail cactus

noun
A Mexican cactus (Aporocactus flagelliformis) having thin, creeping or hanging stems and brilliant crimson-pink flowers.
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