Cephalanthus occidentalis is a species of flowering plant in the family Rubiaceae that is native to eastern and southern North America. Common names include buttonbush, common buttonbush, button-willow, buck brush, and honey-bells.
Cephalanthus occidentalis is a deciduous shrub or small tree that averages 1–3 m (3.3–9.8 ft) in height, but can reach 6 m (20 ft). The leaves are opposite or in whorls of three, elliptic to ovate, 7–18 cm (2.8–7.1 in) long and 4–10 cm (1.6–3.9 in) broad, with a smooth edge and a short petiole. The flowers are arranged in a dense spherical inflorescence 2–3.5 cm (0.79–1.38 in) in diameter on a short peduncle. Each flower has a fused white to pale yellow four-lobed corolla forming a long slender tube connecting to the sepals. The stigma protrudes slightly from the corolla. The fruit is a spherical cluster of achenes (nutlets).[4]
There are two varieties, not considered distinct by all authorities:
Buttonbush is a common shrub of many wetland habitats in its range, including swamps, floodplains, mangrove, pocosin, riparian zones, and moist forest understory.[5] It is a member of the flora in the Everglades.[5]
Waterfowl and other birds eat the seeds. Wood ducks utilize the plant as nest protection, and mallards eat the fruit.[6] Deer browse the foliage, which is poisonous to livestock.[7] Insects and hummingbirds take the nectar, with bees using it to make honey.[5][8] It is a larval host to the hydrangea sphinx, the royal walnut moth, and the titan sphinx.[9]
The species occurs in eastern North America with disjunct populations occurring in the west. In Canada, it occurs from southern Ontario and Quebec east to New Brunswick and south-western Nova Scotia. Besides the eastern United States, and eastern regions of the Midwest, notable areas range into Arizona, the Mogollon Rim, and other mountain ranges; in California, the entire San Joaquin Valley[10] West of the Great Plains and the Rocky Mountains, only western Texas, Arizona, and California find C. occidentalis.
Cephalanthus occidentalis has a number of historical medicinal uses, but it is also toxic due to the presence of cephalanthin.[5][8]
Buttonbush is cultivated as an ornamental plant for a nectar source or 'honey plant' and for aesthetics in gardens and native plant landscapes, and is planted on slopes to help control erosion.[11] Buttonbush is a suitable shrub for butterfly gardens.
The town of Buttonwillow, California was named for the buttonbush (Cephalanthus occidentalis). A lone buttonbush served as a landmark on an old trans-San Joaquin Valley trail, and was used by ancient Yokuts as a meeting place. It later became the site of settlers' stock rodeos. This buttonbush tree is listed as California Historical Landmark No. 492, and is now known as the "Buttonwillow Tree."[12]
Cephalanthus occidentalis is a species of flowering plant in the family Rubiaceae that is native to eastern and southern North America. Common names include buttonbush, common buttonbush, button-willow, buck brush, and honey-bells.
