1. Filipendula rubra (Hill) B.L. Rob. (queen of the prairie)

Pl. 531 h–j; Map 2444

Plants perennial herbs, with stout rhizomes. Stems 0.8–2.5 m long, erect or ascending, lacking spines and thorns, glabrous, hollow, with fine longitudinal ridges. Leaves alternate and basal, short- to long-petiolate. Stipules large, herbaceous, asymmetrically ovate to kidney-shaped, the rounded to cordate bases clasping the stem, those of the basal leaves fused to the petioles. Leaf blades (2–)8–50 cm long, broadly obovate to oblong-ovate in outline, once pinnately compound (the uppermost leaves sometimes merely palmately lobed) with small leaflets at the base and irregularly interspersed among the larger ones, the margins sharply toothed and shallowly pinnately lobed, the upper surface glabrous, the undersurface finely hairy, mostly along the veins, the primary lateral leaflets mostly 2–10, 2–15 cm long, mostly ovate-circular and deeply palmately 3–7-lobed (sometimes without palmate lobes and narrowly oblong-elliptic), the terminal leaflets larger than the lateral ones, nearly circular to broadly fan-shaped or kidney-shaped, palmately 5–9-lobed. Inflorescences dense terminal panicles of numerous flowers, without bracts or bractlets. Flowers perigynous, the hypanthium shallowly cup-shaped, glabrous, somewhat fleshy. Sepals 5(–7), 1.0–1.6 mm long, reflexed, oblong a with rounded tip, glabrous, white- to pink-tinged and usually noticeably veiny, persistent at fruiting. Petals 5(–7), 2–4 mm long, obovate, pink, rarely white. Stamens 15 to numerous, the anthers pink. Pistils 5–15 in a single whorl. Ovary superior, glabrous, with 1 locule, with 2 ovules. Style 1 per pistil, curved, persistent at fruiting, the stigma capitate. Fruits achenes (but appearing similar to follicles), ascending, 5–8 mm long, linear to narrowly oblong, straight or somewhat curved (banana-shaped), often tapered to a short stalk at maturity, glabrous, with 1 seed. June–August.

Uncommon, widely scattered in the Ozark Division (northeastern U.S. west to Wisconsin and Missouri; escaped elsewhere in the U.S. and adjacent Canada). Fens.

This attractive large perennial is quite uncommon and sporadic in the wild, but is widely cultivated as an ornamental in gardens. Steyermark (1963) treated this species as a relict from past times when Missouri had a cooler climate, now with a generally more northern distribution and restricted to a cool microhabitat in southern Missouri. He also noted that the foliage is fragrant. Filipendula rubra, which is uncommon throughout its range, is an obligate outcrosser that often produces relatively small quantities of seed, apparently because many adjacent individuals are clonal, resulting from spread by rhizomes rather than seeds (Aspinwall and Christian, 1992a, b). The main pollinators, at least in Missouri, are bees.