1. Parnassia grandifolia DC.

Pl. 477 e, f; Map 2180

Plants perennial herbs, usually with short rhizomes, glabrous, but often with areas of minute rusty brown dots. Aerial stems 12–45 cm long, erect, unbranched. Leaves in a basal rosette, long-petiolate, the petiole broadened toward the tip, also a solitary bractlike leaf positioned at or below the midpoint of the flowering stem, this sessile or nearly so. Stipules absent. Leaf blades simple, relatively thick and leathery, those of the basal leaves 2.5–10 cm long, those of the stem leaves 0.6–4.0 cm long, both types oblong-ovate or broadly ovate to nearly circular, rounded to broadly and bluntly pointed at the tip, broadly rounded to truncate or shallowly cordate at the base, mostly with 7 or 9 palmate main veins, the margins entire. Inflorescences of solitary flowers naked at the aerial stem tips. Flowers perfect, actinomorphic, hypogynous or slightly perigynous. Hypanthium absent or nearly so. Sepals 5, fused at the very base, 3–4 mm long, elliptic-ovate, usually prominently veined, with broad, thin, white to transparent margins, ascending at flowering, persistent and becoming reflexed at fruiting. Petals 5, 12–22 mm long, spreading, oblong-elliptic to elliptic-ovate, white, with 7–11, prominent, green, mostly parallel veins (the outermost pair with several branches toward the margin). Stamens 5, alternating with the petals, the relatively large anthers attached toward the cordate base, pink. Staminodes 5, opposite the petals, somewhat longer than the fertile stamens, each divided at or toward the base into 3 filament-like stalks, each stalk with a glistening capitate tip. Pistil 1 per flower, of 4 fused carpels. Ovary superior, bright green, with 1 locule, with numerous ovules, the placentation parietal. Style absent or nearly so, the 4 stigmas club-shaped to more or less capitate, outwardly curved. Fruits capsules, 11–16 mm long, ovoid, dehiscing longitudinally, with numerous seeds. Seeds 0.7–1.4 mm long, irregularly ovate to tetrahedral in outline, somewhat flattened, the outer covering loose, somewhat wrinkled, and winglike, the surface, with a minute network of hexagonal pits, brown. 2n=32. August–October.

Scattered in the south-central and eastern portions of the Ozark Division (southeastern U.S. west to Missouri and Texas). Fens and moist calcareous seeps along streams and bluffs.

Steyermark (1963) wrote that, “This species brightens the swampy meadows in autumn with the open white flowers...” The white petals with their prominent green veins make this a most attractive wildflower. The rosettes of thick leaves also are distinctive, even when the plants are not flowering. Regrettably, P. grandifolia is considered of conservation concern in nearly every state within its distributional range. In Missouri, where its status appears to be reasonably secure, it is considered an indicator of high-quality calcareous seepage communities, especially fens.