petalless

adjective [原级]无瓣的

Perennial of the eastern United States having early solitary yellow flowers followed by late petalless flowers; so-called because ice crystals form on it during first frosts.
美国东部的多年生植物，先开单生的黄色花、继而是无瓣的花；在第一次霜冻时有冰晶结在花上。