Unwanted Organism, National Pest Plant Accord
- Scientific Name: Alternanthera philoxeroides
- Origin: Native to South America
- Type: Weed
- Plant Life-form Type: Marginal sprawling
- Taxonomy: (Mart.) Griseb.
- Presence: Locally naturalised, often locally abundant, first record from Northern Wairoa River in 1906
- Habitat: Still and slow flowing water bodies, flooded pasture and cropping land and urban lawns
- Temperature (°C): Dec-20
- pH range: 6.8 - 7.0
- Hardness (ppm): 100 - 250
- Light: Strong
- Height: 600mm
- Difficulty: Demanding
- Notes: Currently our worst sprawling emergent weed, affecting arable and pastoral land in addition to aquatic habitats. A major weed in many temperate countries. Synonyms - Telanthera philoxeroides. Dark green wavy leaves in opposite pairs with hollow sometimes red stems, white clover like flowers during summer. This is a Nationwide Banned Plant. It is illegal to posses or collect it. Any occurance found should be reported to DOC so it an be destroyed. Is a serious weed problem in Northland drains & waterways in warm shallow water. Grows in fresh or brackish water.
- Propagation: Reproduction is vegetative by the extension of prostrate stems or stem fragmentation. The floating fringe of marginal mats is also readily fragmented and dispersed. Seed set is unknown in New Zealand
- Features: Sprawling emergent perennial herb. Leaves are bright green, waxy, and elliptical. They are between 5-10 cm long, up to 2 cm wide, and arranged in opposite pairs on the stem. The white flower looks like a small clover flower and is at the end of a longish stalk. Stems are thick, soft, and hollow, often with a reddish tinge.
- Source: TIFBIS
- Regional: Regional Pest Management Strategy: BOP, MWT, WKO, AUK, WGN.