Alstonia spectabilis subsp. ophioxyloides (F.Muell.) P.I.Forst.

Apocynaceae

Forster, P.I. (1992) Australian Systematic Botany 5(6): 758.

Yellowjacket; Leatherjacket; Jackapple; Milkwood; Hard Milkwood

Living bark quite bitter when crushed. Bark often cork-like.

Twigs and petioles produce a milky exudate. Leaves in whorls of 3-5. Leaf blades lanceolate, elliptic or obovate, variable in size but up to 36 x 12.5 cm, petioles about 1.5-2.5 cm long. Lateral veins about 18-20 on each side of the midrib, curving and often forming loops just inside the blade margin. Lower surface of the leaf blade clothed in pale hairs.

Flowers about 3.5-5 mm diam. Calyx lobes about 1.5-2.2 mm long, densely pubescent on the outer surface, glabrous on the inner surface or sparsely pubescent near the apex. Corolla tube about 3.5-4.9 mm long, densely pubescent on the outer surface, lobes about 1.5-2.6 mm long, densely pubescent on both the inner and outer surfaces, with the right margins overlapping. Stamens inserted near the throat of the corolla tube. Anthers about 0.9-1 x 0.6-0.7 mm.

Fruits about 20-40 cm long. Seeds oblong, acuminate or acute at one or both ends, about 5-8 x 2-2.5 mm, hairs about 5-7 mm long.

Cotyledons about 12-15 x 4-5 mm. First pair of leaves narrowly elliptic, about 12-20 x 4-6 mm, margins smooth, both the upper and lower surfaces of the leaf blades glabrous. At the tenth leaf stage: leaf blade long and narrow, about 12 x 1.5 cm, plant almost entirely glabrous. Seed germination time 20 days.

Endemic to Australia, occurs in WA and NT. Altitudinal range from near sea level to 300 m. Grows in rain forest, monsoon forest and vine thickets.

Alstonia ophioxyloides F.Muell., Fragmenta Phytographiae Australiae 1: 57(1858), Type: Northwrn Territory, Towards the Fitzmaurice River, Oct. 1855, F. Mueller; lecto: GH; iso: K, MEL. Fide Monachino, Pacific Sci. 3: 163 (1949).