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Cephalanthus occidentalis L. Button-bush

Fully expanded globular flower heads with stigmas sticking out from the center of each flower(center global head) and miniature flowers (left and right of cneter globular flower)

Habitat

Button-bush is generally restricted to sites where the roots are covered by water in the spring. It occurs along rivers and streams, around lakes or ponds, or in marshy areas. It is rare in New Brunswick, with known locations around Grand Lake and along the Jemseg and St. Croix Rivers.

Form

Shrub at blooming stage, about 2m tall

Button-bush is a large, spreading shrub, with several stiff branches arising from the base; sometimes it is tree like. It grows to heights of up to 3 m, and is fairly regular in appearance.

Morphology

The leaves are deciduous, simple, and borne in pairs oppositely, or in whorls of three, or sometimes four. Each leaf has a short, stout, grooved stalk (petiole), which has a somewhat persistent, triangular, sharp-pointed stipule on either side at its base. The leaf blade (lamina) is 5–15 cm long, thickish, ovate, elliptic or obovate, wedge shaped to rounded at the base, tapered to a point at the tip, and smooth to wavy around the margin. The upper surface is bright, dark green, and shiny, and the under surface is paler and may be softly hairy, especially along the veins.

Expanded Leaves

The twigs are olive green at first, later turning brown, and have scattered pale lenticels. When leaves have fallen, the leaf scars at a node are connected by raised, stipule- scar lines, and the vein scars in each leaf scar are U- shaped. The lateral buds are embedded in the bark above the leaf scars, and thus are scarcely visible. The pith of the twig is light brown.

The tiny, creamy-white flowers occur at the ends of main shoots, or of stout stalks (peduncles) from axils of upper leaves, in dense, ball- like clusters (globular heads), 2–4 cm across. A swollen stigma occurs at the end of the style that sticks out from the center of each flower. Together, these look like tiny straight pins sticking out all over the surface of the flower cluster, giving a halo effect. The fruits are packed together in ball-like clusters (multiple fruits in globular heads).

Individually, they are tiny, hard, dry brown nutlets, which broaden at their tips with remnants of the four-parted calyx of the flowers.

Multiple fruit cluster on globular heads

The bark of older stems is greyish brown to purplish grey. It may be smooth or somewhat furrowed.

Notes

Button-bush is a species of one of the largest families of flowering herbs, shrubs, and trees, the Rubiaceae. The family contains between 400 and 500 genera, and between 6000 and 7000 species. Among these, are the genera Coffea and Cinchona, the respective sources of coffee and quinine.

The foliage of button-bush is poisonous and unpalatable to livestock. However, the bark and roots, which may also be poisonous, have been used by North American natives for medicinal purposes.