Hypocalymma tenuatum

Hypocalymma tenuatum is a low, spreading shrub that typically grows to a height of 20–35 cm (7.9–13.8 in). Its leaves are linear in outline, 6–9 mm (0.24–0.35 in) long, 0.5–1.3 mm (0.020–0.051 in) wide and 0.4–0.7 mm (0.016–0.028 in) thick. The lower side of the leaves is deeply convex and grooved, with star-like oil glands. The flowers are 5–6 mm (0.20–0.24 in) in diameter, and often arranged in pairs with bracteoles 0.6–1.5 mm (0.024–0.059 in) long at the base. The floral tube is about 1.0–1.3 mm (0.039–0.051 in) long and 2.5 mm (0.098 in) wide and the sepals are egg-shaped, 0.8–1.2 mm (0.031–0.047 in) long and 1.5–2.0 mm (0.059–0.079 in) wide. The petals are white or pale yellow, 2.0–2.5 mm (0.079–0.098 in) long and there are 20 to 25 white or pale yellow stamens, the longest filaments 3.0–3.8 mm (0.12–0.15 in) long. Flowering mainly occurs from August to October, and the fruit is a capsule 2.3–2.7 mm (0.091–0.106 in) long and 2.0–2.5 mm (0.079–0.098 in) in diameter.

This species of Hypocalymma is found with laterite in wandoo woodland or on sandstone outcrops between the Lesueur National Park and Warradarge in the Geraldton Sandplains bioregion of south-western Western Australia.