Eurasian Water Milfoil

Nile region and eastern desert.

Mediterranean region, Europe, Asia, south Africa, north and south America.

Found in fresh water lakes, rivers and canals in the Baluchistan, Baltistan and Kashmir areas from 1000-2500 m.

Submerged perennial. Stems thick, 30-150 cm long, branched, glabrous, rhizome rooting. Leaves 10-25 mm long, pectinate, with 20-26 segments. Spikes terminal, 50-70 mm long, with flowers in whorls of 4 in the axils of bracts; the upper flowers male, the lower female. Bracts 1.5-3 mm long, the upper obovate, entire; the lower: pinnatifid or with a deeply cleft margin. Male flower : sepals 0.5-1 mm long, triangular, obtuse; petals 2 mm long, oblong, cucullate, reddish. Stamens 8, filaments short; anthers 1-1.5 mm long. Female flower: calyx c. 1.5 mm long; petals minute. Ovary c. 1.5 mm long, subglobose; styles short, stigmas plumose. Fruit 2 mm long, subglobose.

Plants mostly monoecious, rarely with bisexual flowers. Stem much branched, 100-250 cm, densely leafy in upper part, sparsely light green warty; internodes ca. 3 cm. Submerged leaves 4- or 5-whorled, pectinate, broadly ovate in outline, 3-3.5 × 1-2.5 cm; segments in 13-16 pairs, filiform, 1-1.5 cm. Inflorescence a terminal spike of 4-whorled flowers, 6-10 cm; bracts reniform or suborbicular, shorter than flowers, broader than long. Male flowers: bracteoles rhombic to elongate, margin entire; calyx broadly campanulate, 0.5-1 mm, 4-parted nearly to middle; petals 4(or 5), pale pink, elliptic, 1.5-2.5 mm; stamens 8, without androphore. Female flowers: bracteoles pectinate, lanceolate in outline; calyx tubiform, 0.7-1 mm, margin shortly lobed; petals absent or minute and caducous. Fruit 4-loculed, subcylindric, ca. 2 × 1.5 mm; mericarps abaxially rounded, smooth or sparsely verrucose along margins. Fl. and fr. Apr-Sep.

Europe, Africa, W. & C. Asia, Himalaya, Siberia, India, east to China and Japan, Alaska, S. America (possibly introduced).

Distribution: Found throughout Europe, Asia, N. & S. America, N. & S. Africa.

3000 m

Fl. Per. May-July.

Stagnant waters, lakes, ditches, slow streams, springs; near sea level to 4200 m, rarely to 5200 m in springs in Xizang. Throughout China [Asia, Europe].

spicatum: arranged in a spike.