Parnassia Linnaeus 1753

Parnassia Linnaeus (1753: 273)

TYPE:— Parnassia palustris Linnaeus (1753: 273)

Description:—Herbs perennial, rosulate, glabrous. Rhizome sympodial, robust. Floriferous stems (scapes) 1 to several, bearing 1 to several cauline leaves or rarely leafless. Basal leaves 2 or several, forming a rosette; stipules membranous; petiole usually long; leaf blade entire. Cauline leaves 1 to several or absent, often sessile and semiamplexicaul. Flower solitary, terminal; hypanthium sometimes present. Sepals 5, usually imbricate. Petals 5, imbricate, white or yellowish or rarely greenish; margin fimbriate, erose or entire. Stamens 5, inserted opposite sepals; anthers longitudinally dehiscent, usually inappendaged but in some species connective projected into a lanceolate appendage. Staminodes 5, inserted opposite petals, terete and entire or flat and divided into lobes or filiform rays, apically somewhat glandular or with distinct globose glands. Gynoecium syncarpous, 3–4-carpellate; ovary superior to semi-inferior, 1-loculed; placentation parietal; ovules numerous; style terminal, short or almost absent; stigmatic lobes distinct, commissural. Fruit a capsule, superior to semi-inferior, sometimes longitudinally angled, loculicidally dehiscent into 3 or 4 valves, with persistent sepals. Seeds numerous, brown, obovoid or oblong, minute, 1–2 mm long; testa thin, membranous, reticulate, smooth; endosperm thin or absent.

The genus Parnassia comprises ca. 60 species distributed predominantly in extratropical regions of the Northern Hemisphere, with several species in northern tropics, including the southernmost known population in northern Sumatra. Two species are recorded in Vietnam (Fig. 1).