Little ironweed (Cyanthillium cinereum) is a species of perennial plants in the sunflower family. It is a fast-growing, annual herb with the capacity to form dense patches in gardens, roadsides, waste grounds and pasture. Annual herb, to 80 (-150) cm tall. Stems unbranched or more commonly few-branched. Leaves petiolate or distal ones sessile; petioles to 1.5 cm, narrowly winged; blade 1.5-5 × 1-1.5(4) cm, obovate or less often elliptic or ovate, base cuneate, apex acute to obtuse, lower surface pilose, usually glandular. Inflorescence of 5 to numerous heads, 13-20-flowered; involucre 2.5-3 mm long; outer phyllaries much reduced, inner phyllaries subequal. Corolla 3-4 mm, exserted 1.5-2 mm from involucre, the tube long and narrow, 2-3 mm, the limbs short, pilose. Achenes 1.2–2 mm long, subfusiform, terete not ribbed, inner pappus white, exserted from involucre and nearly as long as the corollas. The species is native to tropical Africa and to tropical Asia (India, Indochina, Indonesia, etc.) and has become naturalized in Australia, Mesoamerica, tropical South America, and the West Indies.
Little ironweed's facts
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Little ironweed (Cyanthillium cinereum) is considered invasive in many islands in the Pacific Ocean (e.g. Hawaii, Fiji, French Polynesia and Micronesia), New Zealand, Singapore, Costa Rica, Guatemala, Nicaragua, Panama, Galápagos Islands, Cuba, Puerto Rico and the Virgin Islands.
Little ironweed's Behavior & Ecology
little ironweed (Cyanthillium cinereum) usually grows as a weed, thus it needs full sunlight and moderate water availability to grow. It prefers sandy-loam soils but can be found growing on a range of soils with pH ranging from 4 to 6. It is able to tolerate semiarid conditions as well as partial salinity conditions.
Little ironweed's Reproduction
Pollinated by wind. Probably the most common reproduction system in this genus is allogamy with a sporophytic self-incompatibility.
Little ironweed's Relationship with Humans
Little Ironweed have some antibiotic activity and consequently they are frequently used in traditional medicine in India to treat conjunctivitis, dropsy and urinary disorders. In the Philippines, this species is used as an infusion for cough and skin diseases. A poultice from leaves reduces headaches while a root decoction relieves stomach aches and diarrhea. In Thailand, the leaves are used in the treatment of asthma and bronchitis. The young shoots are eaten as a cooked vegetable in Java.