Backhousia tetraptera Jackes

Harrington, M.G. et. al. (2012) Australian Systematic Botany 25: 412-414. Type: Queensland. North Kennedy District: Mount Stuart Townsville, J.W.Elliott JE13 & K.Townsend, 6.February 2012.

Tree up to 15 m tall, but usually 5-8 m tall, single- to multistemmed, coppicing; bark flaky, thin, grey, becoming mottled grey-brown to pink; lenticels on twigs inconspicuous, uniseriate hairs on new growth, 0.1 mm long; subrhytidome layer green, blaze pale brown with pale stripes.

New growth red-purple. Stipules narrowly triangular up to 0.2 mm long, soon falling. Petiole 6-8 mm long, sparsely pubescent. Leaf blade lanceolate to elliptical, 5.5-9 cm long, 1.5-3.8 cm wide, weakly discolorous, glabrous, apex acute to acuminate, base cuneate, margins entire, often undulating; midrib on adaxial surface usually flat, 10-12 lateral veins each side of midrib, angle of 30-45 degrees; intramarginal vein 1 mm from margin. Oil glands visible on both surfaces of fresh leaves as bumps. Juvenile leaves with petiole 1 mm long, lamina ovate to orbicular, up to 3 cm long, red-purple, when dry oil glands appear as pustules on adaxial and abaxial surfaces.

Inflorescences terminal or axillary in upper axils, dichasial with 2-4 branches; 10-flowered. Peduncle ca. 6 mm long; pedicels 1 mm long. Flowers with perigynium 4-angled, 2 x 1 mm pubescent on both surfaces; calyx-lobes 4, with 2 unequal pairs, outer pair 1.5 x 1.5 mm, inner pair ca. 1 x 1 mm, both surfaces shortly pubescent, glands visible; petals 4, white, 2 mm long including claw, ca. 1.5 mm wide, papillose to pubescent on both surfaces, glands occasionally present. Stamens 56-65 in 2 whorls, filaments free, 3 to 6 mm long, anthers dorsifixed, versatile, 0.25 mm long, terminal gland present, dehiscing through 2 longitudinal slits; pollen small, ca. 20 mm, parasyncolpate, oblate, triangular in polar view. Style inserted in a shallow pit on summit of ovary, filiform, 5-6 mm long, scattered hairs near junction with ovary, oil glands sparse, stylar canal open, stigma punctiform; ovary 2 mm long, ca. 1.5 mm wide, summit truncate, pubescent, oil glands sparse, 2-locular, 1 or 2 ovules per locule, placentation basal. Nectaries 4, club-shaped, 1 mm long, attached at the base of the ovary and hidden in a pocket in the perigynium corresponding to the angles.

Fruit dry, indehiscent, enclosed by the inflated perigynium, white with pink blush drying brown; wings on perigynium prominent at maturity. Disseminule 6x5 mm. Seeds up to 0.8 mm long, rarely observed, embryo curved with more or less conduplicate cotyledons; many did not complete development or were parasitised.

Features not available.

Endemic to Queensland, occurs in NEQ near Townsville and currently recorded on Mt Stuart and in Clemant State Forest. Recorded from ca. 500 m altitude. Grows in decidous vine thickets, and in gullies protected from fire.