Species
Sagittaria montevidensis subsp. montevidensis
Common Name(s)
arrowhead
Authority
Sagittaria montevidensis subsp. montevidensis Cham. & Schlecht
Family
Alismataceae
Brief Description
A marginal aquatic plant, up to 2m tall with broad light green arrow-shaped leaves and white flowers that have purple blotches on the inside.
Flora Category
Vascular - Exotic
Structural Class
Monocotyledonous Herbs
Distribution
Locally naturalised, mostly Auckland and Waikato Regions.
Habitat
Still and slow flowing water bodies and wetlands.
Features
Tall emergent perennial or annual herb. Stems are erect from 7 cm to 2m tall. Emergent leaves have a distinctive arrow-shape with basal lobes up to 15 cm long. The rest of the leaf is up to 25 cm long and 20 cm wide. Flowers are 3-petalled, white with a purple basal spot, about 2.5 cm in diameter, arranged in whorls, with male flowers in upper whorls and female flowers in lower. Fruiting heads globose, 1.5-3 cm across, each with up to 2000 seeds. Seeds are brown, wedge shaped, 2-3 mm long, 1.3 mm wide, winged with a characteristic oblique beak.
Similar Taxa
Other Sagittaria species. Sagittaria montevidensis has arrow-shaped leaves but petioles are D-shaped in cross-section and it does not produce creeping rhizomes or tubers. The two other Sagittaria species present in New Zealand (S. subulata and S. platyphylla) do not have arrow-shaped emergent leaves.
Flowering
Summer
Flower Colours
Violet / Purple,White
Fruiting
Autumn
Year Naturalised
1996
Origin
Native to tropics and subtropics of America.
Reason for Introduction
Ornamental pond and aquarium plant
Control Techniques
Notify regional council if found
Life Cycle and Dispersal
Annual or Perennial. Seeds profusely (up yo 100 seeds per flower). Buds off basal rhizome can resprout. Matures quickly. produced seed within 6 months.Seeds. Seeds via water flow and possibly water fowl. Pond escape in floods, deliberate plantings, contaminated diggers, livestock.
Tolerances
Seed is frost hardy.
This page last updated on 21 Aug 2013