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Annonaceae
Isolona zenkeri Engl. & Diels
Nomenclature
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Tribe: MonodoreaeGenus: Isolona
SUMMARY
Tree or shrub to 7(-15) m high; d.b.h. to 15 cm; outer bark brown to dark brown; younger branches drying black, glabrous; old branches brown, finely rugulose, glabrous. Petioles 2-5(-6) mm long, ca. 2 mm in diameter, glabrous, verrucose, leaf lamina inserted on top, very faintly grooved adaxially. Leaf lamina 16-23 cm long, 6.5-8.5 cm wide, length:width ratio 2.5-2.7, narrow obovate to oblanceolate or rarely oblong, coriaceous, glabrous, base rounded to acute, apex abruptly acuminate, acumen 1-2 cm long; midrib glabrous on both sides; secondary veins 11-13 pairs, uniformally curving upwards, glabrous on both sides. Rhipidia 1(-2), usually on leafy branches but occasionally on old leafless branches. Flowering pedicels 3-7 mm, 0.5-1 mm in diameter, glabrous, brown-red. Lower bracts inserted at the base of the pedicel, 2-4, minute, glabrous; margins densely or sparsely covered with short appressed hairs. Upper bract absent. Sepals 2-5 mm long, 2-4 mm wide; length:width ratio 1-1.5, very broadly ovate to ovate, base truncate, apex acute, glabrous, brown-red or green, sometimes persistent in fruit; margins glabrous. Corolla light green to light yellow when immature, light red at anthesis, with small oil cells present on fresh and boiled material, giving a verrucose appearance to the dried material; tube 4-7 mm long, 3-4 mm in diameter, lobe:tube ratio 2.5-3.6, glabrous; lobes 15-25 mm long, 3-4 mm wide, length:width ratio 3.5-6.3, narrowly oblong to lorate, apex acute, glabrous, coriaceous, hanging over receptacle, margins folded inwards. Receptacle 4-5 mm in diameter. Stamens ca. 2 mm long; connective shield ca. 0.2 mm long, glabrous, those of innermost stamens extended over adjacent ovary wall. Ovary ca. 3 mm long, ca. 1.5 mm wide; stigma ca. 2 mm in diameter, glabrous. Fruiting pedicels 5-15 mm long, 2-3 mm in diameter, glabrous, woody. Fruits 3-6.5 cm long, 1.5-3 cm in diameter, length:width ratio 1.5-2.5, globose to ellipsoid, smooth, faintly ribbed longitudinally, glabrous, green turning yellow; pericarp 2-3 mm thick. Seeds 15-20 mm long, 8-10 mm in diameter, broadly ellipsoid; testa smooth, light brown; raphe very slightly thickened, brown; hilum 4-5 mm long, 2-2.5 mm wide, oblong to elliptical.