Knotweed

A highly variable species particularly in size, branching and length of the internodes, shape of the leaves, apex and the length of ochreae. P. mezianum H. Gross is said to be characterized by having obovate-rounded leaves. However, even in the type specimen of P. mezianum H. Gross (Gilgit expedition, 1857, Giles s.n. (K!)) some of the leaves are not rounded but acute and even some of them are acuminate (spiny) therefore the former taxon seems to be a minor variant of P. paronychoides C. A. Meyer ex Hohen.

Subshrubs prostrate or ascending, 5-15 cm tall, papillate. Petiole short, articulate; leaf blade green, linear, 8-15 × 0.7-1.5 mm, both surfaces scabrous, midvein conspicuous, base narrowly cuneate, margin revolute, apex spinose; ocrea broadly lanceolate, 5-8 mm, thinly membranous, hyaline, margin lacerate, apex acute. Flower solitary, axillary; bracts lanceolate, longer than perianth. Pedicel very short. Perianth pinkish, 5-cleft to 1/2; tepals unequal, outer 2 narrowly lanceolate, ca. 2 mm, apex acuminate, inner 3 elliptic, short, apex obtuse. Stamens 8; filaments dilated at base. Achenes included in persistent perianth, shiny, narrowly ellipsoid, trigonous, ca. 2 mm, smooth. Fl. Jun-Aug, fr. Jul-Sep.

Prostrate-subascending, perennial, often glabrous or sometimes scaberulous shrubby herb with thick woody rhizome. Stem woody, stunted or tufted, branched from base, branches spreading or tufted and prostrate, internodes very short, 2-4(-6) mm long, reddish brown, ± completely covered with leaves. Ochreae silvery hyaline, 4-6 mm long, ovate, lacerate, tubular, almost equalling or longer than the internodes. Leaves 7.5-15 x 0.7-1.5 mm, sessile, narrowly linear, acute or mucronate, margins recurved, scabrous. Flowers axillary, solitary, or 2 in each axil, sessile, enclosed in the ochreae. Ochreolae 1-2 mm long, ovate, lacerate, membranous. Tepals 5, pink, 1.5-2.0 x 0.75-1.0 mm, oblanceolate, acute-acuminate with slightly undulate margin. Stamens 4 (-6), filaments short, equal, dilated at the base. Ovary c. 1.0 mm long, lanceolate-ovate, trigonous with 3 styles and capitate stigma. Nuts trigonous, 1.5-2.0 x c. 0.7 mm broad. black, shining, glabrous.

W Xizang (Zanda) [Afghanistan, Kashmir, Kazakhstan, Kyrgyzstan, Pakistan, Tajikistan, Turkmenistan, Uzbekistan; SW Asia].

Distribution: Georgia (Caucasia), Turkmenistan, Pamir-Alai, Iran, Afghanistan, Pakistan and Kashmir (Western Himalayas).

Fl. Per.: July-September.

Gravelly mountain slopes; ca. 3500 m.

This Irano-Turanian element is more common in Eastern Irano-Turanian subregion; usually grows on dry rocky soil, dry ridges, hangs over cliffs. Very common in the dry inner zones, between 1200-4000 m.

Polygonum englerianum H. Gross; P. himalayense H. Gross.

P. mucronatum Royle ex Bab. in Trans. Linn. Soc. 18: 115. 1838; P. meyeri Steud., Nomen. Bot. Ed. 2, 2: 376. 1841; P. lemannianum Meisn. in DC., Prodr. 14: 91. 1856; P. himalaiense H. Gross. in Engler, Bot. Jahrb. 49: 343. 1913; P. mezianum H. Gross. l.c. 342.