Alectryon tropicus (S.T.Reynolds) S.T.Reynolds

Sapindaceae

Reynolds, S.T. (1984) Austrobaileya 2(3): 335.

Usually a small tree seldom exceeding 30 cm dbh. Sapwood surface corrugated. Living bark layer very thin.

Leaf blades about 5-12 x 1-2.5 cm, very gradually tapering into the petiole. Midrib raised on the upper surface. Many lateral veins extend to the leaf margin which is somewhat thickened and vein-like. Young twigs and terminal buds clothed in short, pale, prostrate hairs.

Petals absent. Disk small, complete. Ovules 1 per locule.

Fruit usually 2-lobed, rarely 1-lobed, about 13-22 x 16-28 mm. Pericarp thick (up to 6 mm) gritty. Fruit rupturing irregularly around the equatorial region (circumscissile) to expose the black spot on the testa. Seeds globose, about 8 x 7 x 6 mm. Testa mainly brown except for a black area away from the aril. Aril granular, covering 60-70% of the seed but confined to the base.

Cataphylls(?) similar to the first true leaves but much shorter and narrower. First true leaves narrow, elliptic to oblong to obovate, apex mucronate, base attenuate, midrib raised on the upper surface. At the tenth leaf stage: leaf blade narrowly elliptic to oblong or obovate, rather stiff and hard, apex mucronate, base attenuate, margin undulate; midrib raised on the upper surface; lateral veins about 15-20 on each side of the midrib. Petiole swollen at its point of attachment to the twig. Seed germination time 124 to 165 days.

Occurs in NT close to the border with Queensland and in NEQ and CEQ. Altitudinal range from 240-650 m. Grows in monsoon forest and vine thickets usually on limestone.

Heterodendron tropicum S.T.Reynolds, Austrobaileya 1: 484(1983), Type: Queensland, Mungana, 16 Jun. 1946, H. Flecker N. Q. N. C. No 10423; holo: BRI; iso: QRS.