Vallisneria spiralis, L.

1. V. spiralis L. View in CoL , Sp. Pl. 1015 (1753).

Leaves up to 10 mm wide, basal, ribbon-like, obtuse or rounded at the apex, denticulate towards the apex, with reddish dots or short streaks. Male spathes ovoid, shortly pedunculate. Peduncles of female spathes filiform, becoming spirally coiled after anthesis; sepals of female flowers 1 -75-4 mm, pinkish-white. 2« = 20. S. Europe, extending northwards to N.C. France and C. Ukraine; locally naturalized elsewhere. Bu Ga Gr He Hs It Ju Lu Rm Rs (W, E) Tu [Be Br Ge Ho Hu].

10. Halophila Thouars 1

Submerged marine plants; rhizomes slender, creeping, with 2 scales at each node. Leaves opposite, petiolate or sessile, in 1 or more pairs on short or elongated shoots. Flowers unisexual. Spathes 2-valved, sessile, usually 1 -flowered. Petals absent. Male flowers pedicellate; stamens 3; anthers sessile; pollen moniliform. Ovary sessile or subsessile within the spathe, attenuated into a slender apical beak; styles 3-5, simple, filiform, free. Fruit beaked, with membranous pericarp.

Literature: C. den Hartog, The Sea-grasses of the World 238-268. Amsterdam & London. 1970.

1. H. stipulacea (Forskâl) Ascherson, Sitz.-Ber. Ges. Naturf. Freunde Berlin 1867: 3 (1867). Leaves up to 60 x 8 mm, in single pairson short shoots, shortly petiolate, linear to oblong, obtuse, serrulate, 3-veined, with numerous ascending secondary veins, glabrous or more or less papillose or puberulent. Ovary with 3 styles. Fruit 5 mm, ellipsoid, with a beak 4-6 mm; seeds 30-40. Submerged sand or mud. Mediterranean sea, westwards to Malta. [Cr Gr Si.] (Red Sea, W. Indian Ocean.)

This species entered the Mediterranean Sea via the Suez Canal, soon after the latter was opened in 1869, and appears to be still spreading westwards.