This winter annual, or short-lived perennial, is often found growing in colonies. Its slender, branched stems, 10-30 in. tall, bear leaves divided into thread-like segments. In bud, the flower heads droop; when fully opened, they are erect and upright. The yellow, daisy-like flowers occur on delicate, leafless stalks.Stiff Greenthread’s bloom period is often shortened by an insect larva that consumes the buds.