Description from Flora of China
Parietaria microphylla Linnaeus, Syst. Nat., ed. 10, 2: 1308. 1759.
Herbs weak, glabrous, monoecious. Stems erect or ascending, blue-green when dry, simple or branched, 3-17 cm tall, 1-1.5 mm in diam., succulent, cystoliths dense. Stipules persistent, triangular, ca. 0.5 mm, membranous; petiole slender, unequal in length, 1-4 mm; leaf blade abaxially pale green, adaxially green, obovate or spatulate, unequal in size, 2-7 × 1.5-3 mm, succulent, papery when dry, midvein indistinct distally, lateral veins several, indistinct, abaxial surface honeycombed, cystoliths linear, adaxial, regularly transverse, base cuneate or attenuate, margin entire, somewhat recurved, apex obtuse. Inflorescences often androgynous, compactly cymose-capitate; peduncle 1.5-6 mm, sometimes sessile; glomerules few flowered. Male flowers pedicellate, ca. 0.7 mm; perianth lobes ovate, subapically corniculate; rudimentary ovary minute, conic. Female perianth lobes subequal, oblong, longer lobe subequal to achene. Achene ovoid, ca. 0.4 mm, compressed, smooth, enclosed by persistent perianth. Fl. Jun-Aug, fr. Sep-Oct.
Commonly naturalized in S China and in greenhouses in N China [native to tropical South America].