A straggly shrub up to 15 ft high in the wild. Leaves 11⁄2 to 31⁄2 in. long, 1⁄8 to 3⁄4 in. wide, pointed at the apex; venation prominent. Inflorescence rather open, up to 4 in. long; stamens 3⁄4 to 1 in. long, in some shade of red, with darker anthers.
Native of Australia on the coasts of New South Wales, Victoria, and Queensland; introduced by Sir Joseph Banks in 1788. It has long been grown as a cool greenhouse shrub, but is not suitable for outdoor cultivation except in mild gardens, and even there is best on a wall. The epithet 'citrinus' refers to the fragrance of the leaves.
cv. 'Splendens'. – A fine form with stamens of bright crimson, up to 11⁄2 in. long. It was raised at Kew from Australian seed (var. splendens Stapf, in Bot. Mag., t. 9050).
The following species are allied to C. citrinus and somewhat hardier:
C. linearis (Sm.) DC. Metrosideros linearis Sm. – A shrub to 7 ft high young stems silky-hairy when young. Leaves linear, up to 5 in. long, not more than 1⁄10 in. wide, channelled on the upper surface. Flower-spikes 3 to 5 in. long; stamens up to 1 in. long, crimson. Native of New South Wales.
C. rigidus R. Br. – A shrub to 8 ft high; young stems slightly hairy when young. Leaves linear to linear-lanceolate, up to 6 in. long and 1⁄4 in. wide, sharply pointed, not channelled. Flower-spikes dense, 3 to 4 in. long, stamens dark red, anthers dark brown. New South Wales and Queensland. A fine species, but reports that it is the hardiest of the red-flowered callistemons may perhaps refer to the next species, with which it has been confused in some gardens:
C. subulatus Cheel – A small spreading shrub to about 4 ft high; young wood lustrous rich brown. Leaves glossy green on both sides, awl-shaped, 5⁄8 to 11⁄2 in. long, 1⁄8 to 1⁄4 in. wide. Flower-spikes crimson, 2 to 3 in. long, 11⁄2 to 2 in. wide. Native of E. Victoria and New South Wales. C. subulatus has proved quite hardy at Wisley against a wall of the Alpine House. See also C. rigidus above.