Euphorbia hyssopifolia aka Hyssop Leaf Sandmat

Euphorbia hyssopifolia is in Euphorbiaceae, the spurge family. Its common names include hyssopleaf sandmat and hyssop spurge. It is native to tropical and subtropical parts of the Americas. These include the southeastern United States, Central America, and South America. It has spread beyond that range, including to North Carolina. Kew lists it in tropical climates with dry seasons.

This herb grows fast. It lives as an annual or a short-lived perennial. Its form ranges from upright to sprawling. Plants reach about 1.5 feet [0.46 metres] tall. The stems branch and can be green, red, or yellow. Soft hairs may cover parts, but the tips stay smooth. The simple leaves grow in pairs, each facing its mate. They are narrow and green, sometimes with red or purple marks. Each leaf is about half an inch long. Fine teeth line the edges. The leaf bases are often uneven.

Small groups of flowers sit where leaves meet the stems. These parts, called cyathia, hold the true flowers. White, bract-like parts may grow around them. These may turn pink-red with age. Each tiny flower structure is about one-sixteenth of an inch across. Bloom lasts from spring through fall. The profile notes that it flowers in summer. Warm winters can extend the bloom season. Green seed pods, called capsules, follow the flowers. They sometimes have a red blush. Each has three parts and measures under one-eighth of an inch. The small seeds have wrinkles. Their shape can be four-sided or egg-shaped.

Full sun suits this plant. Some shade helps when the heat is intense. It grows best in sandy or loamy soil that drains well. Acidic to neutral soil suits it. The profile lists moist soil, with dry or wet spells at times. Its preferred temperature range is 65–85°F. Plants grow from seed and can flower while still young. Seeds have little or no dormant rest before growth. This means weed numbers can rise fast. It grows in disturbed ground, sandy washes, canyons, and streambeds. It also becomes a weed in lawns and farm fields. Remove young plants to limit the seeds they make.

Spider mites, aphids, and mealybugs can attack this plant. Diseases include powdery mildew, anthracnose, and rust. All plant parts hold toxic, milky latex sap. Skin contact can cause dermatitis, a mild to severe skin rash. Sap in the eyes can cause lasting harm to the cornea. Eating plant parts can blister the lips and mouth. It is not a food plant. Wear gloves that protect your hands when you handle it. Keep it away from children and pets.