Boerhavia diffusa aka Red Spiderling

Boerhavia diffusa is part of the Nyctaginaceae family. People call it spreading hogweed, red spiderling, and punarnava. Kew gives its native range as the tropics and subtropics. Useful Tropical Plants says no one knows its exact place of origin. It grows in Africa, Asia, the Americas, and Australia. Its range also spans Pacific islands. It lives in open ground, by roads, in fields, and in warm river valleys.

Sources differ on its life cycle and size. Garden accounts call it a perennial herb, which lives for years. Kew lists an annual, which lives one year, or a subshrub. Reported heights range from 0.3–2.3 feet [0.1–0.7 metres], reaching 3.3 feet [1 metre]. Reported spread ranges from 1.6–6.6 feet [0.5–2 metres]. Many branches grow from a long, thick, fleshy taproot. Young stems lie flat, then rise when flowers start to form. Thin stems may creep or twine. They reach 6.6 feet [2 metres] long.

PFAF lists June to September for flowers and ripe seeds. Each flower has both male and female organs. The small fruits have a sticky outer coat. They cling to birds, which help carry them elsewhere. The coat can trap small insects, too. An older account notes harm to young chickens and turkeys. Fruits can stick round their eyes and seal them shut. This sometimes causes death.

Grow this plant in full sun, in soil that drains well. Sandy and loamy soils suit it. It grows in acid, neutral, and mildly alkaline soil. It can grow in dry or moist ground and withstand drought. PFAF gives USDA zones 8–11 but doubts its hardiness in Britain. Reports from Australian gardens record survival at 19°F [−7°C]. That result may not apply where winters stay cold and wet. A warm bed with shelter near a sunny wall fits the suggested conditions.

People cook the leaves as greens or add them to soups. They also cook the seeds and mix them with cereals. Indigenous people in central Australia have eaten the roots. The plant also serves as animal feed. People have long used it in Ayurveda and other healing traditions. This does not prove that home treatments are safe or work. PFAF lists no known toxic hazards. Still, the sticky fruits pose a risk of physical harm. The plant can become weedy and host the cotton aphid. It also hosts viruses linked to mosaic diseases in aubergine and zucchini.