Eucalyptus percostata

Eucalyptus percostata, commonly known as the rib-capped mallee or Devils peak mallee, is a species of mallee that is endemic to South Australia. It has smooth bark, lance-shaped adult leaves, flower buds in groups of seven, creamy white flowers and cup-shaped to conical fruit. It is only known from a few locations in the Flinders Ranges.

Description
Eucalyptus percostata is a mallee that typically grows to a height of 3-10 m and forms a lignotuber. It has smooth whitish bark that is coppery when new. Young plants and coppice regrowth have broadly lance-shaped to broadly egg-shaped leaves that are 50-100 mm long and 30-60 mm wide. Adult leaves are the same shade of green on both sides, lance-shaped, 70-120 mm long and 12-25 mm wide tapering to a petiole 10-22 mm long. The flower buds are arranged in leaf axils on a peduncle 8-20 mm long, the individual buds sessile or on pedicels up to 2 mm long. Mature buds are pear-shaped, 8-12 mm long and 6-7 mm wide with a conspicuously ribbed, rounded to conical operculum. Flowering from May to September and the flowers are creamy white. The fruit is a woody, cup-shaped to conical capsule 6-8 mm long and 5-9 mm wide with the valves near rim level.

Taxonomy
Eucalyptus percostata was first formally described in 1990 by Ian Brooker and Peter Lang in Journal of the Adelaide Botanic Gardens from material collected on a track east of Devils Peak, near Quorn in 1986. The specific epithet (percostata) is from Latin meaning "conspicuously ribbed", referring to the operculum.

Distribution and habitat
Rib-capped mallee grows in woodland and mallee in the southern Flinders Ranges between Quorn and Napperby.