Named by Robert Brown to commemorate Alexander Macleay (1767–1848) Colonial Secretary of New South Wales.

Perennial herbs to about 3 m tall. Sap yellow. Leaves divided into a primary and secondary lobing system with the veins radiating from the base. Flowers small, many in a showy cluster. Petals absent. Fruit a capsule with 1-6 seeds.

Suckers and seed.

Tall plants with yellow sap; leaves with rounded lobing and veins radiating from the base; flowers small and numerous in long, plumed clusters.

2 species from temperate E Asia, China and Japan.

Source: Spencer, R. (1997). Papaveraceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.