Syzygium claviflorum (Roxb.) Steud.

Craven, L. A., 2019, Studies in Papuasian Syzygium (Myrtaceae): 1. Subgenus Perikion revised, Blumea 64 (2), pp. 115-122 : 118-119

4. Syzygium claviflorum (Roxb.) Steud. — Fig. 1 ; Map 2

Syzygium claviflorum (Roxb.) Steud. (1841) 657. — Eugenia claviflora Roxb. (1832) 488. — Acmenosperma claviflorum (Roxb.) Kausel (1957) 609. — Type: Icones Roxburghianae no. 2499 (lecto K, selected by Soh & Parnell 2015).

Eugenia leptantha Wight (1841) 14. — Syzygium leptanthum Nied. (1893) 85. — Eugenia leptalea Craib (1931) 649. — Eugenia claviflora Roxb. var. leptalea (Craib) M.R.Hend. (1949) 255. — Type: Griffith (holo, n.v.), Burma, Mergui.

Tree (sometimes flowering as a treelet) to 28 m tall, to 60 cm dbh; bark brown, dark brown, grey-brown, brownish, light-grey, creamy-grey, mottled grey, light fawn. Vegetative branchlet terete or compressed, rounded or angled, 0.8–2.1 mm diam; bark dull, smooth or cracked (occasionally slightly striate), not glandular-verrucose, flaking in relatively large pieces. Leaf lamina 5–19.3 by 1.6–6.6 cm, 1.6–3.9 times as long as wide, narrowly elliptic, elliptic, ovate, narrowly ovate, narrowly obovate or obovate; base narrowly cuneate, cuneate, obtuse or attenuate (sometimes approaching rounded); apex long acuminate or acuminate; acumen recurved (or occasionally flat); margin flat (or occasionally slightly revolute, often appears undulate but this may be an artefact of drying); primary and secondary venation distinctly different with secondaries relatively little developed and not or rarely joining the intramarginal vein; primary veins 12–27(–37) on each side of the mid-rib, in median part of the lamina at a divergence angle of 60–70° and 2–10 mm apart; intramarginal vein present, 0.5–3 mm from margin, secondary intramarginal vein present (sometimes difficult to discern). Petiole 2–7 mm long. Reproductive seasonal growth unit with a reproductive zone only. Inflorescence among the leaves or below the leaves and then ramuline or ramine, rarely terminal, 2- to many-flowered, spicate, umbellate or paniculate, up to 1.5–5 by 2–6 cm, major axis 0.3–1.8 mm thick at the midpoint, bark smooth or commonly granular-papillate; bracts deciduous; bracteoles subtending each flower, caducous. Flowers white, cream or green, calyptrate or not (petals coherent and falling as a cap or discrete and falling individually). Hypanthium dull, visibly gland-dotted, minutely (but distinctly) wrinkled; stipitate; elongated goblet-shaped or extremely narrowly funnel-shaped; 9.8–23 by 1.7–5.6 mm; stipe 6.5–17 mm long. Calyx lobes 4 or 5, very depressedly triangular, transversely narrowly semielliptic or transversely oblong, 0.3–0.8 mm long. Petals 6–8, coherent and then caducous and falling as a cap or deciduous and then falling individually, 2–3 mm long. Staminal disc flat ( Fig. 1 : 1.1). Stamens numerous, 3–8 mm long. Style 3–8 mm long. Placentation axile-median; placenta distinctly lobed, narrowly semiobovoid to semilinear-obovoid. Ovules c. 9–16 per locule, pendulous, arranged in two longitudinal rows (one row on each placental lobe). Mature fruit red, ellipsoid or very broadly obovoid and flat at the apex, 12–14 by 9–10 mm (excluding the calyx), the hypanthium rim not appreciably expanding in fruit; seed 3 mm across; cotyledons interlocked by an intrusive weakly ramifying tissue.

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

Habitat & Ecology — Oak forest, rainforest, swamp forest, edge of mangroves and riparian forest, riverine forest, lowland hill forest, tall open forest, forest on low stony hills, oak-beech forest. Altitude 0–2750 m.

Notes — A broad circumscription of S. claviflorum is taken in the present treatment. The species occurs from India and southern China southwards through Malesia to north-eastern Australia and it merits a detailed study throughout its range. I suspect that several distinct biological entities are included in the present circumscription. One specimen, Pleyte 1075, has leaves up to 35 by 11.4 cm wide but its flowers and inflorescences conform to variation within the species. It was recorded as being a shrub of 2 m tall. In Papuasia, flowers are seen to become consistently larger and leaves smaller in specimens from higher altitudes. In addition to being good-sized forest trees, plants may also be treelets or shrubs .

In S. claviflorum and the species most closely allied to it (e.g., S. suberosum ), the hypanthium could be interpreted as being not stipitate (i.e., the hypanthium uniformly tapers from base to apex) but there is a point at which the parenchymatous tissue in the ovarian region stops and a darker-coloured proximal tissue begins. The darker tissue is interpreted as being the stipe. Syzygium claviflorum is similar to S. leptopodium but in general it differs in having larger leaves, a cuneate vs an often ± rounded leaf base, subcoriaceous vs chartaceous leaves (in montane material), larger flowers, more flowers per inflorescence, a tendency towards a lateral rather than terminal inflorescence, rounded or compressed branchlets vs ± tetragonous branchlets. These features all more or less break down. Anther size, however, appears to distinguish flowering material, the anthers being about 0.6–0.8 mm long in S. claviflorum and 0.2–0.4 mm long in S. leptopodium . Also, S. claviflorum usually has glandular, ± twisted staminal filaments; those in S. leptopodium are eglandular and ± straight.

The style articulates about 1 mm above its base, leaving a stub in mature fruit. Fruit sometimes develops without seeds, and then lacks the characteristic shape of fertile fruit, being narrowly obovoid.

Figures

Map 2 Distribution of Syzygium claviflorum (Roxb.) Steud.

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).