Little ironweed

Cyanthillium cinereum is an annual herb that typically grows between 20 to 100 cm in height. The stems are erect, ribbed, and covered with fine, silvery hairs. The leaves are lanceolate to broadly ovate, measuring 3 to 5 cm in length and 2 to 3 cm in width, with undulate to serrate margins and an acute to acuminate apex. The upper leaf surface is hairy without glands, while the lower surface is densely covered with cylindrical hairs, T-shaped hairs, and capitate glands. The plant produces terminal or axillary, paniculate inflorescences with campanulate capitula. Each capitulum is 5 to 6 mm long, with a flat, glabrous receptacle and a campanulate involucre composed of 3 to 4 series of phyllaries. The phyllaries are green with a purple apex and are piliferous along the margin. The florets number between 25 to 30, with funnel-shaped corollas that are either purple or white. The achenes are clavate, densely pubescent, and have a pappus of two series of bristles.

Cyanthillium cinereum is native to tropical Africa and tropical Asia, where it thrives in a variety of habitats, including open fields, disturbed areas, and along roadsides. It has become naturalized in tropical regions of the Americas, the West Indies, and parts of Australia, often growing in similar disturbed and open environments. The plant is well-adapted to warm, tropical climates and is commonly found in regions with a dry season followed by a wet season.

Cyanthillium cinereum is not typically cultivated for ornamental or agricultural purposes. However, it can be grown in tropical gardens as a low-maintenance plant that adds color with its purple or white flowers. It prefers well-drained soils and full sun exposure. The plant is drought-tolerant once established and can thrive in poor soil conditions. Propagation is usually done through seeds, which germinate readily under warm conditions. Due to its invasive potential in some regions, it should be planted with caution to prevent it from spreading beyond the intended area.

Cyanthillium cinereum is not widely used in traditional medicine or agriculture. However, in some regions, it may be used as a source of nectar for pollinators due to its showy flowers. The plant is also sometimes used as a ground cover in disturbed areas to prevent soil erosion. Its ornamental value is limited, but it can be appreciated for its natural beauty in tropical landscapes. In certain parts of its range, it may be considered a weed due to its ability to colonize disturbed areas quickly.