Alstonia muelleriana Domin

Apocynaceae

Domin, K. (1928) Bibliotheca Botanica 89(4): 1081. Type: Endemisch in Nordost-Queensland.Regenwalder bei Lake Eacham und Yarraba (DOMIN II. 1910).

Yellowwood; Hard Cheesewood; Bitterbark; Milkwood, Hard; Milky Yellowwood; Yellow Jacket; Hard Milkwood

Bright yellow layer just beneath the dead bark. Living bark extremely bitter when chewed and may be poisonous.

Milky exudate from the petioles and twigs. Leaves in whorls of three, sometimes four. Leaf blades variable in size, up to 19 x 7 cm, petioles about 0.6-0.8 cm long. Lateral veins about 10-18 on each side of the midrib.

Flowers about 4.5-5 mm diam. Calyx lobes about 0.8-1.4 mm long, densely pubescent. Corolla tube about 3.2-4.8 mm long, pubescent, lobes about 2.1-3 mm long, with the right margins overlapping, glabrous on the outer surface but pubescent on the inner surface. Stamens inserted near the middle of the corolla tube. Anthers about 0.9-1.1 x 0.3-0.4 mm.

Fruits about 12-39 cm long. Seeds oblong, acuminate or acute at one or both ends, about 5-6 x 1.6-1.8 mm, hairs about 8-10 mm long.

Cotyledons elliptic, about 10-13 x 3-7 mm. First pair of leaves ovate to elliptic, about 15-20 x 6-9 mm, margins entire, both the upper and lower surfaces of the leaf blade clothed in pale-coloured hairs. At the tenth leaf stage: leaves hairy on the upper surface; petioles hairy. Seed germination time 16 to 24 days.

Widespread in NEQ. Altitudinal range from near sea level to 1000 m. This species grows to quite a large tree in rain forest but is also found in marginal situations and is a characteristic species in regrowth areas. It is a resilient species and can cope with fires when young by producing coppice shoots from the base and root suckers. Also occurs in New Guinea.

Apical dominance is maintained in a rather unusual way. One of the branches in the terminal whorl becomes more upright and eventually orthotropic and assumes the role of leader and therefore the mainstem until the next whorl of branches is produced.

Produces a useful general purpose timber.

Wood specific gravity 0.81. Cause et al. (1989).

Alstonia muelleriana Domin var. muelleriana, Bibliotheca Botanica 89(4): 1081(1928). Alstonia angustifolia A.DC., Prodromus 8: 409(1844), Type: Wall.! list n. 1650 .. in Singapore. Alstonia muelleriana var. parvifolia Domin, Bibliotheca Botanica 89(4): 1081(1928), Type: Savannenwaldern am Waterfall Creek bei Yarraba (DOMIN I. 1910).