水珠草 shui zhu cao

Circaea lutetiana Linnaeus f. quadrisulcata Maximowicz, Mém. Acad. Imp. Sci. St.-Pétersbourg Divers Savans 9 [Prim. Fl. Amur.]: 106. 1859; C. lutetiana subsp. quadrisulcata (Maximowicz) Ascherson & Magnus; C. maximowiczii (H. Léveillé) H. Hara; C. maximowiczii f. viridicalyx (H. Hara) Kitagawa; C. maximowiczii var. viridicalyx H. Hara; C. mollis Siebold & Zuccarini var. maximowiczii H. Léveillé; C. quadrisulcata (Maximowicz) Franchet & Savatier.

Plants 15-80 cm tall. Rhizomes not tuberous. Stem glabrous or rarely with sparse falcate hairs. Leaves narrowly to broadly ovate to oblong ovate, 4.5-12 × 2-5 cm, base rounded to subcordate, rarely broadly cuneate, margin denticulate, apex shortly to long acuminate. Racemes 2.5-30 cm, simple or branched at base. Flowering pedicels perpendicular to axis of raceme, with stipitate glandular hairs, without a bracteole at base. Floral tube 0.6-1 mm. Sepals reflexed, most commonly purple, 1.3-3.2 × 1-1.7 mm. Petals commonly pink, 1-2 × 1.4-2.5 mm, apical notch 1/3 to slightly more than 1/2 length of petal; nectary conspicuous, exserted beyond floral tube. Fruiting pedicel and mature fruit 5.3-8.5 mm. Fruit pyriform to subglobose, 2.2-3.8 × 1.8-3 mm, rounded, usually obliquely, to pedicel, with prominent ribs and deep sulci. Ovary locules 2. Seeds 2. Fl. Jun-Aug(-Sep), fr. Jul-Sep. 2n = 22.

Cool-temperate deciduous forests and mixed deciduous-boreal forests; near sea level to ca. 1500 m. Hebei, Heilongjiang, Jilin, Liaoning, Nei Nongol, Shandong [N Japan, Korea, Russia; E Europe from vicinity of Moscow across Siberia between 50°-60° N].

Molecular and morphological analyses indicate that Circaea lutetiana Linnaeus is a distinct species from C. canadensis. Circaea canadensis subsp. canadensis occurs in E North America.