Syzygium suberosum Craven, 2019

Craven, L. A., 2019, Studies in Papuasian Syzygium (Myrtaceae): 1. Subgenus Perikion revised, Blumea 64 (2), pp. 115-122 : 121-122

10. Syzygium suberosum Craven , sp. nov. — Fig. 1 ; Map 4

From Syzygium claviflorum (Roxb.) Steud. it differs in the often corky branchlets; the persistent calyx lobes ; and the strongly ramifying chalazal tissue in the embryo. (In S. claviflorum the branchlets are always smooth; the calyx lobes are deciduous;and the chalazal tissue in the embryo is weakly ramifying.) — Type: Van der Sijde BW 5565 (holo CANB!; iso L n.v., MAN n.v.), Indonesia, Papua Barat, Sidei (c. 50 km W of Manokwari), primary forest, alt. 50 m, 28 Mar. 1958.

Etymology. The specific epithet is derived from the Latin suber, cork, in reference to the corky branchlet bark.

Shrub, treelet or tree; to 7 m tall; bark grey, fissured and flaking. Vegetative branchlet terete or quadrangular, rounded, or winged, 1.5–5 mm diam; bark dull, smooth and corky, not glandular-verrucose, persistent. Leaf lamina 8.5–19 by 2.5–7.4 cm, 2.6–4 times as long as wide, narrowly elliptic or elliptic; base cuneate, obtuse, narrowly cuneate or attenuate; apex long acuminate or acuminate; acumen flat or recurved; margin flat; chartaceous to coriaceous; primary and secondary venation distinctly different with secondaries relatively little developed and not or rarely joining the intramarginal vein; primary veins 10–17 on each side of the mid-rib, in median part of the lamina at a divergence angle of 60–70°, 4–17 mm apart; intramarginal vein present, weakly arched, 1.5–8 mm from margin, secondary intramarginal vein present or absent. Petiole 3–5 mm long. Reproductive seasonal growth unit with a reproductive zone only. Inflorescence leafless, median axillary or lateral (ramuline), 1- to few-flowered, cymose, up to 2 by 0.5–2.5 cm wide (0.5 cm when 1-flowered), major axis 1 mm thick at the midpoint, bark smooth; bracts persistent; bracteoles subtending each flower, persistent to deciduous. Flowers white, calyptrate (petals coherent and falling as a cap). Hypanthium dull, glandular-verrucose to smooth, visibly gland-dotted; stipitate; stipitately very narrowly obconic, or elongated-goblet-shaped to very narrowly elongated-goblet-shaped, 18–21 by 2.5–3 mm wide; stipe 6–8 mm long. Calyx lobes 5 (often irregular in size and sometimes nearly obsolete), transversely semielliptic or transversely narrowly semielliptic, 0.3–1 mm long, persistent. Petals c. 8, coherent and caducous, up to 2 mm long. Staminal disc flat ( Fig. 1 : 1.10). Stamens numerous, 9–10 mm long. Style c. 10.5 mm long. Placentation axile-median; placenta more or less linear and flattened. Ovules c. 10 per locule, pendulous, arranged in two longitudinal rows (one row on each placental lobe). Fruit red, yellow or orange (probably mature (but galled) fruit recorded as red, youngish fruit recorded as yellow-orange), glandular-verrucose, finely ribbed, very narrowly obconic or very narrowly pyriform, 20–28 mm by 5 mm wide (excluding the calyx), the hypanthium rim not appreciably expanding in fruit; seed narrowly obovoid and deeply impressed at the apex, 3 mm across; cotyledons interlocked by an intrusive strongly ramifying tissue, collateral.

Distribution — Indonesia (Papua Barat).

Habitat & Ecology — Oak-dominated primary forest, primary forest. Altitude 5–50 m.

Note — The inflorescence is a short, cymose structure consisting of monads and/or triads. The smallest inflorescence seen consisted of a single monad, and the largest comprised two lateral monads and a terminal triad. The shape of the staminal disc is very distinctive.

Acknowledgments Studies of Papuasian Syzygium at CANB were commenced by Tom Hartley and LAC in the 1970s. It is a matter of regret they could not be pursued to fruition at that time;two papers only being produced. Tom’s enthusiasm for the genus and his excellent field knowledge then assisted the project considerably in refining species concepts; these have been further refined in recent years by LAC as the work has progressed. Cath Busby obtained geocode data for those collections for which the data was not recorded on labels. Nunzio Knerr generated the distribution maps ready for final editing. Siobhan Duffy, in good humour, printed numerous digital images of type specimens for study, prepared the staminal disc diagrams from LAC’s crude drawings, and prepared the final versions of the distribution maps. The curators and/or directors of the following herbaria have made available specimens and/or images that have been used in my ongoing studies of Papuasian Syzygium and I sincerely thank them for this assistance:A, B, BISH, BM, BO, BRI, CANB, E, K, L, LAE, LY, MEL, NY, P, WRSL.The facilitation of loans, provision of digital images,and/or examina- tion of specimens have been of great benefit to the research on Syzygium . Those who have assisted me variously in the foregoing and other matters include, in no particular sequence, Emily Wood, Melinda Peters, Wayne Takeuchi, Eve Lucas, Ana Claudia Araujo, Shelley James, Frédéric Danet, Gaëtan Guignard, Mélanie Thiébaut, Jan-Frits Veldkamp,Wim Vink, Gerard Thijsse,Nicolien Sol, Kirsten Cowley,Thomas Zanoni, Rusty Russell,Anton Igersheim, Adele Smith.

Figures

Map 4 Distribution of Syzygium saundersii Craven (●), S. sleumeri Craven (■), S. subamplexicaule Merr. & L.M.Perry (▲) and S. suberosum Craven (♦).

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).