The understory or understorey layer lies between the canopy and the forest floor. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Shrublands eucalypt assemblages, with a dense low understory of tussock grasses. Preferred leaves are in areas of low understory vegetation density, but high canopy vegetation density. Wetter oak woodlands historically had a substantial shrub understory, primarily snowberry. Mild to moderate fires burn in the forest understory, removing small trees and herbaceous groundcover. Cacao trees grow well as understory plants in humid forest ecosystems. Fire also kept oak woodlands on drier soils free of a shrub understory. It is more common in forests with ample shrubby or grassy understory. Forest floors have a diverse set of understory shrubs and fungi. Ferns and moss grew in the forest understory. The high stem turnover regime supports a diverse herbaceous understory. This subspecies occupies productive sites and often has a lush understory of wildflowers and grasses. More frequent fires result in a pyrophytic shrub understory. Without disturbance, trees will encroach on a grassland and cast shade, which suppresses the understory.