The Aruncus genus contains only one species, which has distribution in the temperate regions of North America and Eurasia. It has a native range in North America and elsewhere it is a garden plant that escaped to the wild.
Bride's-feathers is an erect perennial forb, clump-forming, growing from 4 to 6 feet high and 2 to 4 feet wide on stout stems. Stems can be smooth, have some sparse hair or be densely hairy.
The leaves are all on the stem, alternate, and 2 to 3 pinnate - that is divided into 2 or sometimes 3 sections. The entire blade is somewhat ovate on a long stalk that partially sheaths the stem. The individual leaflets are also stalked, dark green, broadly ovate to lanceolate, toothed, sometimes double-toothed. There is one main rib vein with a pinnate venation between the laterals which curve upward. Leaflets narrow gradually to the base, but some may have a shallow heart-shaped base. Tips are pointed. Terminal leaflets are not lobed as they are in the False Goat's-beard, Astilbe biternata.
The inflorescence is a many branched panicle composed of numerous raceme-like branches, each branch containing many small flowers spaced along the branch, which can be up to 12 inches long, creating a very showy effect. The species is dioecious - male and female flowers on different plants.
The individual flowers are bowl shaped, with hypanthiums only .5 to 1.0 mm wide. The calyx has 5 spreading triangular shaped sepals, to 1 mm in length. The 5 petals are white, elliptic to more broad above the middle, with wedge shaped bases, 0.5 to 1.5 mm long. There is a nectar ring inside the flower. Male flowers usually have 20 stamens rising from a position between the calyx and the nectar ring. They are longer than the petals. Female flowers have similar petals and sepals but an undeveloped nectar ring and undeveloped stamens. They have 3 carpels, each with a style.
Seed: Fertile flowers usually produce a follicle from each carpel, with the stalk recurved and the follicle held inverted. As the flowers are spaced along the raceme, the seed follicles look like a chain of seeds. Both sepals and style are persistent on the follicle. Each follicle holds 2 to 4 small seeds.
Habitat: Bride's-feather is a temperate zone plant, preferring partial shade and adequate moisture. In cooler parts of the growing area it will grow in full sun if it has plenty of moisture. Hot and humid weather area are to be avoided. The plant grows from thick woody rhizomes, which form clumps rather than spreading colonies. The root system takes a while to get established and the plant is difficult to move but root divisions may transplant. It is said to be deer resistant.
Names: The genus Aruncus is from the Greek word, aryngos, meaning 'goat's-beard. The species dioicus means 'dioecious', meaning 'of two houses', that is - sexes are on separate plants. The author names for the plant classification are two-fold - ‘Walter’ refers to Thomas Walter (1740-1789) British born American botanist, best know for his 1788 catalogue of plants of South Carolina, Flora Caroliniana, in which this plant was listed. His work was amended in 1939 by ‘Fernald’ who is Merritt Lyndon Fernald (1873-1950) American botanist, Harvard Professor, scholar of taxonomy, author of over 850 papers, editor of the 7th & 8th editions of Gray’s Manual of Botany.
The common name of Goat's-beard is one of those confusing names because there is another whole genus of plants in North America referred to as 'goat's-beards', that being the Tragopogons with two represented here - T. pratensis, known as Meadow Goatsbeard, and T. dubius, known as Yellow Goatsbeard or Yellow Salsify.
Varieties: There are 14 known varieties of Aruncus dioicus in the world, with 4 of those found in North America. Differences involve the sizes of seed follicles, size of seeds and size of styles and whether the leaflets are hairy or not. These differences apply only to native plants. You can find a detailed key in Flora of North America, Vol. 9 (Ref. #W7) Planted specimens or nursery stock may be a mixture or of an imported variety.
Above: The inflorescence is a branched panicle of raceme-like flower bearing branches.
Below: An inflorescence branch with numerous male flowers, both open and still in bud.
Below: 1st photo - the flowers are separated by sex on different plants. Each is stalked with a bowl shaped hypanthium, 5 small sepals and 5 larger petals. Male flowers shown here. 2nd photo - individual leaflets have toothed edges, sometimes double-toothed as seen here.
Below: The leaf is 2 or 3 times parted with individual stalked leaflets.
Below: The stem can be hairy or smooth as seen here. The leaf stalk (with reddish tints) forms a partial sheath at the stem node, from which also rises a flowering branch.
Notes: Bride's-feather is not found in the wild in Minnesota and if you find it, it has escaped from some garden. The species was introduced to the Wildflower Garden in 1919 by Eloise Butler. She used the classification Aruncus sylvester, which today is considered to be a synonym of A. dioicus, and specifically it relates to two of the North American varieties, var. vulgaris and var. acuminatus. It did not appear in Martha Crone's 1951 Garden census.
The native range of Bride's Feather is in the Canadian Provinces, while in the U.S. it may have native areas and introduced areas. It is grown in many gardens as an ornamental where temperatures permit.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"