Particular attention should be given to the risks associated with use of the plant as an ornamental, and as a contaminant of pasture seeds. Countries not yet infested should consider all likely pathways for entry, and apply quarantine measures accordingly. ManagementīIOSECURITY There is a high risk of introducing this weed. Used to reduce fevers, as a tea to reduce blood pressure, and many other medical conditions. In doing this, it is helped by the production of chemicals from the rat's tail that prevent the growth of other species as well inhibiting the germination of their seed. It can compete with native species preventing their regeneration. The weed can cause severe environmental impacts, particularly via its effective on biodiversity. It might also be a contaminant of pasture seeds. Over long distances, spread has occurred with the use of the weed as an ornamental and its association with the international trade in plants. Spread occurs by seed these can be moved in soil, hay, and attached to animal fur, clothing and to machinery. After flowering, the spikes become woody as the fruits develop within cavities along their length. Each flower has five petals fused together for part of their length to form a tube inside the tube are two stamens (male parts) and a white style (female part). Flowers, dark blue, purple or violet, about 1 cm across, borne on spikes, 10-45 cm long and 1-3 mm thick, at the top of the stems, without stalks (Photo 3). Stems are somewhat square in cross-section when young, greenish with purple tinge, becoming round and woody with age. Leaves, oval, 5-8 cm long and 3-6 cm wide, opposite along the stems, with a wrinkled surface, and saw-like margins (Photo 2). DescriptionĪ small, perennial shrub, usually 1-1.5 m tall, but occasionally up to 2.5 m. Its invasiveness is due to its production of large amount of seeds: one plant is able to produce more than 7000 seeds a year, with germination within 2 weeks. A problem of disturbed land, although also invasive in cultivated and waste lands, as well as areas of natural vegetation. Invasiveness & HabitatĪn invasive weed of plantations, pastures, grasslands, forests and forest margins, secondary fallows, sand dunes, waste areas, and roadsides (Photo 1). ![]() Waterhouse & Norris state that the genus is of Central American origin others consider that it is native to Asia and the Pacific. It is recorded from Australia, American Samoa, Cook Islands, Federated States of Micronesia, Fiji, French Polynesia, Kiribati, Marshall Islands, New Caledonia, Niue, Northern Mariana Islands, Palau, Papua New Guinea, Samoa, Solomon Islands, Tokelau, Tonga, Vanuatu, and Wallis and Futuna. Asia, Africa, North, South and Central America, the Caribbean, Oceania. Some authorities think that Stachytarpheta urticifolia is the same as S tachytarpheta cayennensis, while others prefer to keep them separate - the flowers of Stachytaropheta cayennensis are pale blue to white. There has been considerable confusion and misidentifications between these. ![]() There are a number of other Stachytaropheta species: Stachytaropheta cayennensis, Stachytarpheta indica, and Stachytaropheta jamaicensis. Common Nameīlue rat's tail it is also known as dark blue snakeweed. Close-up of flower, rat's tail, Stachytarpheta urticifolia.
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