Flora of New Zealand Series

starwort

Amphibious monoecious herb. Aquatic stems to c. 1 m long, often forming dense mats in water or on mud. Submerged lvs not markedly different from rosette or floating lvs, 4-10-(25) × 2-4-(6) mm, linear-spathulate, spathulate or obovate, but never linear, 3-, 5-, or 7-nerved; free veins 0; apex rounded or slightly emarginate; rosette lvs to 10 × 6 mm, broad-elliptic to suborbicular, entire; terrestrial lvs usually smaller and rarely > 5 × 3 mm. Fls in axils of rosette lvs, solitary or 1 ♂ and 1 ♀ together. Bracteoles white, falcate, persistent. Filaments c. 2 mm long; anthers c. 0.2 mm long. Styles 2-3.5 mm long, persistent and recurving at fruiting. Fr. subsessile, 1.2-1.7 mm diam., orbicular, pale; mericarp faces ± flat; wing rather narrow, usually extending round the mericarp; commissural groove wide, deep, tapering towards the top.

N.; S.: widespread and often abundant; St.: local.

Europe, N. Africa 1912

In and around areas of still and slow-moving water, also commonly in swampy areas on mud.

FL Dec-Feb.

Starwort is by far the most common aquatic sp. of the genus in wet areas modified by human activity, e.g. in ponds, lakes, ditches, drains. C. stagnalis was treated as indigenous by Allan (1961) in the main text, but in the Supplementary Notes, was stated to be probably introduced.