They are grouped in unbranched, indeterminate clusters such as racemes, spikes, corymbs or umbels. The inflorescences are generally umbellate, and often arranges in compound umbels, caouttules, panicles or races. Often, they grow in racemes, spikes, or umbels. The flowers are regular, pentamerous, and borne in racemes, corymbs, or umbels. The dome-shaped umbels of steely blue or white flowers have whorls of spiny basal bracts. The cluster is a compound umbel, and each umbel contains several smaller umbels (umbellets). The umbels and umbellets usually have no upper or lower bracts. The main umbel is further divided into several secondary umbels known as umbellets or umbellules. The distinctive umbels and floral nectaries attract pollinating insects. Flowers are pale greenish yellow produced in large compound umbels. Six to 25 straight pedicels are present, each measuring that support the umbellets (secondary umbels). The flowers are produced in dense umbels diameter, each flower small, with five greenish-white petals. The flowers are solitary or borne in umbels. Common greenbrier has greenish white flowers that form in umbels of 3-20 flowers. It has green flowers in three-rayed umbels.