13. Polygonum arenastrum Boreau, Fl. Centr. France, ed. 3. 2: 559. 1857; Webb & Chater in Tutin et al., Fl. Europ. 1: 79. 1964; Cullen & Coode in P.H.Davis, Fl. Turk. 2: 277. 1967; Rech. f. & Schiman-Czeika in Rech. f., Fl. Iran. 56: 78, 1968; R.R.Stewart, Ann. Cat. Vasc.Pl. W. Pak.& Kashm. 203. 1972; Munshi & Javeid, Syst. Stud. Polygon. Kashm. & Himal. 55. 1986; Boulos, Fl. Egypt 1: 28. 1999. (Fig. 15, E-H).
Polygonum calcatum Lindm. in Bot. Not. 102. 1904; Polygonum aequale Lindm. in Svensk. Bot. Tidskr. 6: 692. 1912; P. aviculare L. subsp. aequale (Lindm.) Asch. & Graebn., Syn. Fl. Mittel. Europ. 4: 848, 1913; Polygonum ebracteatum Munshi & Javeid, l.c. 56. syn. nov.
Prostrate to procumbent, profusely branched, glabrous annual herb; stem 5-20 (-25) cm, usually forming a mat. Leaves 4-15 (-20) x 2-5 (-7) mm, sessile to subsessile, elliptic, lanceolate, acute with entire to denticulate margin, all the leaves almost ± equal in size. Ochreae silvery hyaline, ovate, with few faint veins, ± lacerate, fimbriate, 2.5-3 mm long, less than half the internodes. Inflorescence solitary, axillary or few flowered axillary fascicles. Flowers 1-1.2 (-1.5) mm across, pedicel 0.5-1.0 mm long. Ochreolae 0.5-0.75 mm long, ovate, acute. Tepals 5, parted more than half, 1-2 x 0.4-0.6 mm, elliptic-oblanceolate, obtuse, univeined. Stamens 6, filament short and broader at the base, unequal.
Ovary 1-2.5 x 0.25-0.5 mm, trigonous with three styles and capitate stigmas. Nuts 2.5 (-3) x 1-1.5 mm, ovate, trigonous, dark brown, glabrous, dull, included within the perianth.
Fl. Per.: July-Sept.
Type: not precisely indicated.
A pluri-regional element. Very close to P. aviculare L., sometimes difficult to separate but differs from it by its procumbent or prostrate and mat forming habit; perianth divided more than half and nuts 2-2.5 (-3) mm long. Grows between 2000-3500 m in open places and lawns as a weed; Distribution: Almost throughout Europe except the extreme north, Turkey, Iraq, Iran, Afghanistan, Pakistan and Kashmir.
Munshi & Javeid, l.c. described a new species P. ebracteatum from Kashmir and differentiated their new species from P. aviculare by its prostrate habit and from P. arenastrum by its very short perianth tube. The present author could not examine the type. However, judging from the description it seems to be a minor variant of P. arenastrum. In P. arenastrum the perianth tube is also divided more than half of its length.