About Hypocalymma robustum (Endl.) Lindl.
Hypocalymma robustum is an erect, hairless shrub or small shrublet that typically grows 0.3 to 1.5 meters (1 foot 0 inch to 4 feet 11 inches) tall, and produces many stems. Its leaves are arranged in opposite pairs, shaped linear to narrowly oblong. They measure 14–25 mm (0.55–0.98 in) long, 1.2–2.5 mm (0.047–0.098 in) wide, are flat in shape, and covered with small glands. Flowers grow in pairs in leaf axils, and are either stalkless or borne on a stalk up to 3 mm (0.12 in) long. The bracts are small and broadly lance-shaped, while the bracteoles are broadly elliptic and 2–3 mm (0.079–0.118 in) long. The sepal lobes are egg-shaped to almost round, 2–3 mm (0.079–0.118 in) long, pale pink, with glands located in their centre. The petals are pink, 4.0–5.5 mm (0.16–0.22 in) long. There are between 35 and 70 stamens arranged in several rows; the longest filaments measure 4.5–6.5 mm (0.18–0.26 in) long and are joined at the base. Flowering occurs between June and November. The fruit is 3–4 mm (0.12–0.16 in) long, around 4.5 mm (0.18 in) wide, and 3 mm (0.12 in) thick.
This species grows in woodland on gravelly lateritic and sandy soils in undulating terrain, ranging from near Bindoon to Pemberton in south-western Western Australia. This range includes Perth and the Leeuwin-Naturaliste National Park, within the Jarrah Forest, Swan Coastal Plain, and Warren bioregions.
Its attractive flowers and compact size make H. robustum a popular desirable garden plant. It requires a climate with dry summers, needs good drainage, and prefers a position in full sun or partial shade. It has moderate frost resistance, and can be propagated from semi-mature cuttings or seed.
