Mazus pumilus aka Japanese Mazus

Mazus pumilus is also known as Japanese mazus. It is part of the Mazaceae family. It is native to temperate and tropical parts of Asia. Records place it in China, Korea, Japan, Taiwan, and Bhutan. They also list parts of India, plus Thailand and Vietnam. Other sites include Indonesia, the Philippines, and New Guinea. It is not native to Britain or Ireland. Kew calls it an annual or a subshrub. Plants For A Future calls it an annual.

This small plant grows about 0.7 feet [0.2 metres] tall. The supplied species account does not state its full-grown width. Nor does it describe leaf shape or stem texture. In the wild, it grows in wet grassland and beside streams. It also grows along trails and in waste fields. Forest edges provide more sites where it grows. Chinese records place it in mountain grassland, too. These sites lie at 3,937–12,467 feet [1,200–3,800 metres]. Thus, it grows on disturbed ground and in wetter natural sites.

Plants For A Future lists blooms from May through October. Seeds ripen in these months as well. Each flower has both male and female organs. Insects move pollen between the flowers. The species evidence gives no flower colour or fruit shape. The RHS page describes flowers for the genus as a whole. It also describes creeping growth at that level. Neither detail confirms this species' colour or growth form.

The species account says it needs light and cannot grow in shade. It prefers moist soil that drains well. It can grow in sand, loam, and clay soils. The stated pH range spans slightly acid to slightly alkaline soil. It includes neutral soil as well. Plants For A Future lists garden beds as a growing site. It gives no firm answer on outdoor hardiness in Britain. Its other growing notes concern the genus, not this species. Those notes give less certain guidance for Japanese mazus itself.

Records list cooked young leaves as food. Plants For A Future rates its food value as low. It lists past uses for fever and constipation. It also lists use to prompt menstrual flow. The account notes plant juice as a traditional typhoid treatment. These records do not prove that the treatments work. Nor do they prove that these uses are safe. The source lists no known hazards, but this does not prove safety. It reports no weed potential and no other uses. The supplied evidence names no specific pests or diseases.