Syzygium subg. Perikion

Craven, L. A., 2019, Studies in Papuasian Syzygium (Myrtaceae): 1. Subgenus Perikion revised, Blumea 64 (2), pp. 115-122 : 116-117

Key to Papuasian Syzygium subg. Perikion species based on vegetative and flowering characters. 1. Syzygium attenuatum (Miq.) Merr. & L.M.Perry — Fig. 1 ;

Map 1

1. Leaf lamina base cuneate, narrowly cuneate, attenuate,

obtuse or sometimes rounded.................... 2 Syzygium attenuatum (Miq.) Merr. & L.M.Perry (1939) 185. — Jambosa attenuata Miq. (1855) 437. — Type: Junghuhn s.n. (L n.v.), Indonesia, 1. Leaf lamina base cordate or truncate................ Java, Uangaram.

............................ 9. S. subamplexicaule

Tree to 33 m tall, to 90 cm dbh; bark grey, reddish brown, pink, 2. Branchlet bark corky............... 10. S. suberosum

grey and brownish, brown, flaky-fibrous, flaking longitudinally 2. Branchlet bark not corky......................... 3

in long fibrous pieces, papery, or smooth. Vegetative branchlet 3. Hypanthium dull............................... 4 terete or angled, 2–4 mm diam; bark dull, very finely cracked, 3. Hypanthium glossy................. 7. S. saundersii not glandular-verrucose, persistent. Leaf lamina 5–12 by 2.6– 4. Hypanthium up to 9 mm long..................... 5 5.4 cm, 1.4–2.5 times as long as wide, elliptic, narrowly elliptic 4. Hypanthium more than 9.5 mm long................ 8 or oblong; base cuneate; apex acuminate or long acuminate;

acumen recurved; margin flat or very slightly revolute; coria- 5. Reproductive seasonal growth unit with a reproductive zone

ceous; primary and secondary venation generally similar with all only (i.e., leaves not present within the growth flush)... 6

or nearly all secondaries joining the intramarginal vein; primary 5. Reproductive seasonal growth unit with distinct vegetative

veins 14–34 on each side of the mid-rib, in median part of the and reproductive zones (i.e., leaves present within the growth lamina at a divergence angle of 60–70° and 1.5–8 mm apart; flush)............................ 1. S. attenuatum intramarginal vein present, 0.5–1 mm from margin, secondary 6. Calyx lobes 2–4............................... 7 intramarginal vein absent. Petiole 4–11 mm long. Reproductive 6. Calyx lobes 5....................... 5. S. kokomo seasonal growth unit with distinct vegetative and reproductive 7. Leaf lamina up to 3 cm long, elliptic or obovate, apex acute zones. Inflorescence terminal, few- to many-flowered, panicu- or obtuse.............................. 3. S. carrii late, up to 4.2–7.5 by 2.4–5 cm, major axis 0.5–1.3 mm thick 7. Leaf lamina usually more than 4 cm long (rarely as short as at the midpoint, bark glandular-verrucose; bracts caducous;

bracteoles subtending each flower or subtending lateral flowers 2 cm long), narrowly elliptic, elliptic, narrowly ovate or ovate,

of a triad but with the terminal flower ebracteolate, caducous. apex long or short acuminate or acute. 6. S. leptopodium

Flowers pinkish white, calyptrate (petals coherent and falling as a cap). Hypanthium dull, smooth, visibly gland-dotted or not; angled laterally (i.e., 2-costate) to ribbed; stipitate; elongated goblet-shaped; 6–8.5 by 3–4 mm; stipe 1.5–2.5 mm long. Calyx lobes 5, triangular, 0.4 mm long. Petals 5, coherent and caducous, 1.2–1.8 mm long. Staminal disc descending ( Fig. 1 : 2.5). Stamens c. 80, 2 mm long. Style 1.5 mm long. Placentation axile-median; placenta narrowly oblong, very slightly prominent, not peltate. Ovules c. 16 per locule, pendulous, arranged in two longitudinal rows (one row on each placental lobe). Mature fruit white, or cream, or greenish white with apex pinkish, smooth, wrinkled or ribbed, obconic, 8–13 by 5–6.5 mm (excluding the calyx), the hypanthium rim or scar appreciably expanding in fruit; seed not seen.

Distribution — Indonesia (Aru Islands, Papua Barat, Papua), Papua New Guinea.

Habitat & Ecology — Lower montane forest (moderately dry, Eucalyptopsis dominant), primary rainforest, Castanopsis - dominated lower montane ridge forest, relict tree in cleared montane forest. Altitude 0–1300 m.

Note — Fruit with seeds have not been seen. All studied fruiting collections have been either galled or not seeded (in which case fruit development per se apparently can proceed without seed development).

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).