Euphorbia hirta aka Asthmaplant

Euphorbia hirta is a small annual in the spurge family. Common names include asthma weed, hairy spurge, and garden spurge. It comes from tropical and subtropical parts of the Americas. It now grows across many other warm regions. These include Africa, Southeast Asia, Australia, and the Pacific islands. It grows in lawns, fields, roadsides, and garden beds. It also takes root in cracks between paving stones.

Garden plants reach about 0.5–1 foot [0.15–0.3 metres] tall. They spread about 1–2 feet [0.3–0.6 metres] wide. Tropical accounts report heights up to 1.6 feet [0.5 metres]. Stems may lie flat or rise above the ground. A central taproot supports one or several stems. The round stems have a red-purple tint and dense hairs. These hairs range from short and white to longer yellow-brown strands. The stems hold a white, milky sap. Leaves grow in opposite pairs and have toothed edges. They are narrow to oblong, with pointed tips. Green leaves may show red-purple marks. Poor soil can turn the leaves red.

Tiny flowers form round groups where leaves meet the stems. These flower structures, called cyathia, have no petals. Their shades range from green through tan to pink. North Carolina State Extension lists flowering in fall. The fruit is a small, hairy, yellowish capsule. Each capsule has three lobes and splits when dry. It releases tiny, red-brown seeds, which have four sides. One plant can produce thousands of seeds within months. Seeds need light to sprout and have no dormant phase. Wind and water can carry them to new sites.

This fast-growing plant prefers sun and light, well-drained loam. It also tolerates shade, poor soil, and other soil types. It needs moderate water and cannot withstand frost. Warm summers allow it to grow as a temperate annual. It can serve as ground cover, edging, or a container plant. Yet its heavy seed crop can make it troublesome. Pulling or hoeing removes plants; mulch can limit seed growth. Aphids, mealybugs, and spider mites may attack it. Powdery mildew and other fungal diseases can also occur.

People use this species in traditional medicine in tropical countries. Sources also record cooked young leaves and shoots as famine food. These uses do not establish that eating it is safe. All parts are toxic when eaten, and pets face risks too. Sap can inflame skin and cause serious eye damage. Wear gloves when handling it and avoid swallowing plant parts. Medicinal use needs expert guidance because large doses can cause vomiting.