Zygogynum polyneurum (Diels) Vink

Vink, W., 2016, The Winteraceae of the Old World. VIII. Some Zygogynum species from New Guinea, Blumea 61 (1), pp. 41-50 : 48

12. Zygogynum polyneurum (Diels) Vink — Fig. 1

Zygogynum polyneurum (Diels) Vink (1985) 54. — Drimys polyneura Diels (1916) 244. — Bubbia polyneura (Diels) B.L.Burtt (1936) 3. — Type: Ledermann 8986 (B).

Shrub or treelet 2–18 m high. Branchlets rather stout, (light) brown. Leaves: petiole (2–)3–15(–20) mm long, broadly groov- ed to flat above, rounded below, (greyish to dark) brown; blade oblanceolate, 13–25 by 3.3–8(–10) cm, thick-chartaceous, in sicco light grey below; apex acute and 0–1.5 cm (broadly) acuminate, base cuneate; midrib broad, impressed above, strongly prominent below; secondary nerves at 55–70° with midrib, arcingly joined at some distance from margin, faint above, distinct to faint below. On lower leaf surface stomata and unspecialised cells white, also over secondary nerves; oil cells (not apparent to) abundant. Inflorescences with 5 –10 partial inflorescences, these 3–10.5 cm long, with firm axes, 3–22- flowered, flowers inserted on axes 1st or 2nd (to 3rd) order; empty bracts below inflorescence few; pedicels 1–7 mm long, rather firm. Only young buds and fruitlets seen. Calyx 2-lobed. Petals 4, free. Stamens 8–27; thecae apically distinctly but shortly separated to touching; connective not prolonged. Carpels 2–10, free; stigma as long as or shortly overtopping carpel apex, but adaxial side of carpel can be short and thus in fruit stigma apical to apico-ventral; ovules 6–13. Fruitlets a soft berry, globose to obovoid, red turning (bluish) black, usually in sicco showing seeds, up to 9 mm diam, base obtuse to rounded, without or with a 0.3–2 mm long stipe; stigma 2–6 mm long; fruitwall without brachysclereids; pulpa almost not between seeds. Seeds 3–15, ellipsoid or obovoid, somewhat curved, 2.7–4 by 1.5–3 by 1.3–2.3 mm; testa thin, brittle, dark grey to dull black, very finely pusticularly ribbed.

Distribution — W. part of PNG.

Ecology — Mid-montane or Agathis -forest at 650– 2000 m altitude. Flowerbuds and fruits September–December.

Specimens examined. PAPUA NEW GUINEA, West Sepik, Sandaun Prov., N slopes Bewani Mts, Mt Yungat, Kerenga LAE 56548 (CANB n.v., L), 1030 m alt.; Telefomin Dist., Busilmin, Vinas & Wiakabu LAE 59392 (L), 1500 m alt.; Mt Stolle, Salas & Stephens KP 163 (L), Regalado & Katik 1258 (L), 1600 m alt., 1265 (L), 1282 (L), 2000 m alt.; East Sepik Prov., Etappenberg, Ledermann 8986 (B), 850 m alt., 9242 (K); S. Highlands Prov., Mt Bosavi, Jacobs 9489 (L, US), 600–700 m alt.

Notes — In very young buds of Ledermann 9242 I could observe a free apex of the floral axis, surrounded by the carpels. In general the secondary nerves are far apart in relation to their length; however, in the type material this pattern is distorted by distinct intercalaries, hence the name. Zygogynum polyneurum is distinguished from Z. umbellatum (see Notes there) by the soft fruitlets lacking brachysclereids in their walls, often showing the seeds in sicco.

Figures

Fig. 1 Carpels, all with ventral side to the left, and at the same magnification. – a. Zygogynum archboldianum; b. Z. bosavicum; c. Z. clemensiae; d. Z. cruminatum; e. Z. cyclopensis; f. Z. ledermannii; g, g'. Z. longifolium; j. Z. megacarpum; h. Z. montanum; i. Z. oligocarpum; k, k'. Z. polyneurum; l. Z. schramii; m. Z. sororium; n. Z. staufferianum; o. Z. umbellatum (a. Brass 12712; b. LAE 58822; c. Clemens 4596; d. LAE 69143; e. Royen & Sleumer 6396; f. Takeuchi 6212; g. Vink BW 8413; g'. Robbins 2004; j. Burley & Ismail 4618; h. LAE 61131; i. Schlechter 16470; k, k'. Jacobs 9489; l. Vink BW 8458; m. Ledermann 11898; n. Balgooy 968; o. Boden Kloss s.n.).