Aquatic and Wetland Vascular Plants of the Northern Great Plains

26. Rosaceae, the Rose Family

3. Spiraea L. -- Meadosweet

1. Spiraea alba Du Roi

Small, erect shrub 0.4-1 m tall, often in colonies; stems puberulent when young, eventually brown to reddish-brown and glabrous. Leaves dark green, alternate, often rather crowded, narrowly elliptic to oblanceolate, 2.5-8 cm long, 0.8-1.5(3) cm wide, glabrous to puberulent, acute to obtuse, serrate with ascending teeth, cuneate to somewhat rounded at the base; petioles short, to 1 cm long; stipules none. Flowers numerous in a terminal, oblong to pyramidal panicle 0.5-2.5 dm long, the branches and tiny bracts puberulent. Sepals 5, broadly triangular, 1-1.5 mm long, puberulent; petals 5, white to slightly pinkish, subrotund, 1.5-3.5 mm long; stamens 25-50, the filaments persisting and forming a fringe around the inside of the hypanthium; carpels 5, seldom fewer, separate, styles 0.5-1.3 mm long; hypanthium cupulate, 1-1.8 mm long. Fruit a group of 5 (seldom fewer), 2- to several-seeded follicles, these 2.5-3.5 mm long and extending well above the hypanthium at maturity. Flowering late Jun--Aug, fruiting Aug--Sep. Wet meadows, stream banks, marshes and swamps, often in sandy soils; occasional in e, c and nw ND, e and the Black Hills, SD; (Newf. and n Que. to Alta., s to VA, NC, IN, n MO and e SD).


Spiraea alba, flowering branch.

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