Syzygium busuense T.G.Hartley & L.M.Perry

Craven, L. A., Damas, K. Q. & Cowley, K. J., 2021, Studies in Papuasian Syzygium (Myrtaceae): 2. The furfuraceous species of subg. Syzygium, Blumea 66 (1), pp. 57-81 : 65

7. Syzygium busuense T.G.Hartley & L.M.Perry — Fig. 2 : 3.3; Map 3

Syzygium busuense T.G.Hartley & L.M.Perry (1973) 206. — Type: NGF (Floyd) 5683 (holo A n.v.; iso CANB!, LAE n.v.), Papua New Guinea, Morobe Province, near Lae, Busu [River], in a virgin forest near a creek.

Tree to 7 m tall, to 10 cm dbh; bark longitudinally fissured. Vegetative branchlet quadrangular, angled, 4‒5 mm diam; bark dull, smooth, persistent. Leaf lamina 30.7‒33.7 by 7.5‒12 cm wide, 2.8‒4.1 times as long as wide, slightly oblong to el- liptic; base cuneate; apex short acuminate to acute; acumen flat; margin flat; coriaceous; primary and secondary venation distinctly different with secondaries relatively little developed and not or rarely joining the intramarginal vein; primary veins 20‒34 on each side of the midrib, in median part of lamina at a divergence angle of 50‒60° and 10‒20 mm apart; intra- marginal vein present, weakly arched, 1‒4 mm from margin, secondary intramarginal vein absent. Petiole 15‒20 mm long. Reproductive seasonal growth unit with a reproductive zone only. Inflorescence leafless, cauline, paniculate, up to 12.5 by 9 cm, major axis c. 5 mm thick at the midpoint, bark furfura- ceous; bracts persistent; bracteoles subtending each flower, persistent. Flowers white. Hypanthium dull, smooth, not visibly gland-dotted, occasionally proximally compressed and then proximally 2-costate; stipitate; stipitate-obconic, 7‒8 by 4.5‒5 mm; stipe c. 1 mm long. Calyx lobes 5, semi-elliptic, 1–1.5 mm long. Petals 4, calyptrate (coherent and falling as a cap). Staminal disc ascending ( Fig. 2 : 3.3). Stamens c. 60, c. 8.5 mm long. Style 7.5‒8 mm long. Placentation axile-basal; placenta a small flattened cushion. Ovules 5‒7 per locule, ascending, arranged irregularly. Open flowers and fruit not seen.

Distribution — Papua New Guinea.

Habitat & Ecology — Lower montane forest along river bank, virgin forest near creek. Altitude 150 m.

Notes — 1. A few stamens were adhering to the inflores- cence of NGF 5683, otherwise the mature androecium is not known.

2. The continued existence of S. busuense in the vicinity of Lae (i.e., at Busu River) is doubtful due to the extensive clear- ing for housing and vegetable gardening that has occurred in recent decades.

Figures

Fig. 2 Staminal disc types in Syzygium species. Series 1: Flat; series 2: descending; series 3: ascending; series 4: raised.