Arachis glabrata aka Rhizoma Peanut

Arachis glabrata is a low plant that spreads and lives for years. It belongs to the pea family, Fabaceae. Its names include perennial peanut and rhizoma peanut. Its native range starts in eastern Bolivia. It runs through central Brazil to northeastern Argentina. Other records include Paraguay too. It grows in warm tropical and subtropical regions. It is kin to the peanut grown for food.

Plants reach about 1 foot (0.3 metres) tall. One garden source gives the same width. Yet rhizomes, or underground stems, spread to form lasting ground cover. The stems have no branches. They stand upright or lie in part along the ground. They grow about 0.16–1.15 feet (0.05–0.35 metres) long. A deep, woody taproot supports a thick mat of rhizomes. These stems sit just below the soil surface. They store food to fuel new shoots after cutting or grazing.

The flowers range from bright yellow to orange. Insects pollinate them, but many blooms do not ensure seed. Most types tested for use as feed yield almost none. So growers start new stands with pieces of rhizome. PFAF says the flowers may be edible. It gives their taste as pea-like or bean-like. Useful Tropical Plants lists no known food use. These accounts leave doubt about human food use. Both sources report no known hazards. This does not prove the plant is safe. Neither lists a use as medicine.

This plant grows fast in warmth, in sun or light shade. It prefers moist soil that drains well. It can grow in sand, loam, or clay. Acid soil suits it. Neutral soils and those a little alkaline support growth too. Growth is best when the monthly mean temperature exceeds 20°C. Frost kills top growth, but warmth and moisture bring new shoots. Drought may kill the tops while the rhizomes live on. PFAF lists USDA zones 8–11. Long wet spells pose more risk than dry spells. UF/IFAS reports poor tolerance of waterlogged soil beyond one to two weeks.

Farmers grow perennial peanut for grazing, hay, and silage. Its feed value can match alfalfa. Rhizomes help rooted stands endure drought and repeated grazing. Some Florida stands have yielded well for more than 25 years. Root bacteria fix nitrogen, which can help nearby plants too. Uses include green manure, soil cover, and growth beneath tree crops. Gardeners also grow it as ground cover for its looks. PFAF records no risk of it becoming a weed. Weeds can hinder young plants as they take hold. A clean planting bed helps at this stage.