Syzygium bicolor Merr. & L.M.Perry

Craven, L. A., 2019, Studies in Papuasian Syzygium (Myrtaceae): 1. Subgenus Perikion revised, Blumea 64 (2), pp. 115-122 : 117

2. Syzygium bicolor Merr. & L.M.Perry — Fig. 1 ; Map 1

Syzygium bicolor Merr. & L.M.Perry (1942) 286. — Type: Brass 13018 (holo A n.v.; iso BRI!, LAE!), Indonesia, Papua Province, Idenburg River , 6 km SW of Bernhard Camp, alt. 1200 m, Mar. 1939.

Tree to 30 m tall, to c. 60 cm dbh; bark reddish brown or grey, flaky or slightly rough. Vegetative branchlet terete, compressed or quadrangular; rounded, angled or weakly winged, 1–2.5 mm diam; bark dull, smooth to slightly striate; not glandular-verrucose, persistent. Leaf lamina 3–6 by 1.3–4 cm, 1.3–2.3 times as long as wide, elliptic to broadly elliptic; base cuneate, obtuse or narrowly cuneate; apex short acuminate, acuminate or acute; acumen flat or recurved; margin flat or revolute; cartilaginous; primary and secondary venation distinctly different with secondaries relatively little developed and not or rarely joining the intramarginal vein; primary veins 5–7 on each side of the mid-rib; in median part of the lamina at a divergence angle of 50–70° and 4–12 mm apart; intramarginal vein present, weakly or strongly arched, 1–4 mm from margin, secondary intramarginal vein present (rarely absent, in large leaves a tertiary intramarginal vein may be evident also). Petiole 2.5–5 mm long. Reproductive seasonal growth unit with a reproductive zone only. Inflorescence terminal, or terminal and distal axillary, few- to many-flowered, paniculate, up to 2– 5 by 1– 5 cm, major axis 1–1.5 mm thick at the midpoint, bark glandular-verrucose; bracts caducous or deciduous; bracteoles caducous. Flowers white, calyptrate (petals coherent and falling as a cap). Hypanthium dull, glandular-verrucose or striate (sometimes distinctly glandular-verrucose distally and striate for the remainder), visibly gland-dotted; stipitate; stipitately very narrowly obconic; 10–12 by 3–4 mm; stipe 2–4.5 mm long. Calyx lobes 4 or 5, transversely semielliptic or semicircular, 1 mm long. Petals 4–6, coherent and caducous, 3–3.5 mm long. Staminal disc flat ( Fig. 1 : 1.4, 1.5). Stamens numerous, 6–8.5 mm long. Style 6–8.5 mm long. Placentation axile-median; placenta oblong, narrowly oblong or narrowly oblong-triangular, the 2 distal lobes appressed, or subobtriangular and proximally rounded with the 2 distal lobes well separated. Ovules c. 12–22 per locule, ascending, arranged in two longitudinal rows (one row on each placental lobe). Fruit not seen.

Distribution — Indonesia (Papua), Papua New Guinea.

Habitat & Ecology — Rainforest, moist mid-mountain forest. Altitude 1200–1800 m.

Note — Flowers occur in groups of 2, 3, 4 or 6 (rarely singly) on the terminal internodes and often the axis apex is ‘knobbly’ with two or more insertion points for flowers, perhaps indicating that a reduction in the number of internodes has occurred in the inflorescence. It may be that axis reduction has been a feature of inflorescence evolution in this species.

Figures

Map 1 Distribution of Syzygium attenuatum (Miq.) Merr. & L.M.Perry (●), S. bicolor Merr. & L.M.Perry (■) and S. carrii T.G.Hartley & L.M.Perry (▲).

Fig. 1 Diagrams of staminal disc types occurring in Syzygium subg. Perikion species, showing staminal discs that are flat (1.1–1.10), descending (2.5), ascending (3.2) and raised (4.2). Within the flat staminal disc type, structure may differ in the degree of ‘lip’ projection at the inner edge of hypanthium apex (1.4, 1.5, 1.6 and 1.9) and the presence of a grooved petal insertion point (1.10).