5. Stachys palustris Linnaeus, Sp. Pl. 2: 580. 1753.
沼生水苏 zhao sheng shui su
Herbs perennial. Rhizomes robust. Stems usually much branched, 60-110 cm, densely retrorse pubescent, nodes and angles sparsely hispid. Stem leaves petiole 2-3 mm; leaf blade oblong-lanceolate to ovate-lanceolate, 3-8 × 1.2-1.5 cm, appressed puberulent, densely so on veins and abaxially, base rounded to shallowly cordate, margin serrate-crenate, apex acute to acuminate. Spikes long; verticillasters 6-flowered, ± close together except for lower ones; lower floral leaves subsessile, similar to stem leaves; upper ones long acuminate, entire, shorter than verticillasters; bracteoles ca. 1 mm, early deciduous. Pedicel ca. 1 mm. Calyx tubular-campanulate, ca. 7 mm, grooved, villous, glandular puberulent, puberulent inside, 10-veined, accessory veins inconspicuous; teeth triangular-lanceolate, ca. 3 mm, apex spinescent, ± reflexed; fruiting calyx campanulate, conspicuously pouched. Corolla purple to red-purple, ca. 1.3 cm, sparsely puberulent outside, puberulent on throat; tube ca. 7 mm; upper lip straight, broadly ovate, ca. 3 × 2 mm; lower lip ± spreading, ca. 6 × 6 mm; middle lobe reniform, apex rounded; lateral lobes ovate. Nutlets brown, triquetrous ovoid, glabrous. Fl. Jun-Aug, fr. Aug-Sep.
Marshy areas along lakes and streams in tall grass; 500 m. Xinjiang [India, Kazakhstan, Kyrgyzstan, Mongolia, Russia, Tajikistan; SW Asia, Europe, North America].
A polymorphic species. Specimens from Xinjiang resemble var. subcanescens Ledebour.