16. Cycas pectinata Buchanan-Hamilton, Mem. Wern. Nat. Hist. Soc. 5: 322. 1826.
篦齿苏铁 bi chi su tie
Cycas circinalis Linnaeus var. pectinata (Griffith) Schuster; C. dilatata Griffith; C. jenkinsiana Griffith; C. pectinata Griffith; C. wallichii Miquel.
Trunk cylindric, often dichotomously branched toward apex and gradually thickened toward base, up to 16 m × 60 (-90) cm, apex not tomentose; bark gray or white-gray, smooth toward base of trunk. Leaves 40-80(-100), 1-pinnate, 0.7-1.2 (-1.5) m × 20-30(-40) cm; petiole compressed orbicular in cross section, 10-35 cm, with 6-15 spines along each side above middle part; leaf blade oblong-lanceolate, flat or occasionally slightly "V"-shaped in cross section, pale brown tomentose when young; leaflets in 50-100 pairs, longitudinally inserted at 50-60° to rachis, straight to falcate, 9-20 cm × 5-7 mm, thickly, leathery, midvein flat adaxially, sulcate when dry, raised abaxially, base decurrent, margin slightly recurved, apex acute, pungent. Cataphylls triangular, 3.5-4.5 × 1.5-2 cm, brown tomentose, apex soft. Pollen cones fusiform, 30-45 × 10-15 cm; microsporophylls cuneate, 3.5-5 × 1.2-2.5 cm, densely pale brown tomentose, apex thickened, with an upcurved point 3-4 cm. Megasporophylls more than 30, tightly grouped, 13-18 cm, densely yellowish brown silky hairy; stalk 4-7 cm; sterile blade deltoid-ovate or suborbicular, 7-9 × 6-10 cm, margin pectinate, with 29-37 lobes 2.5-3.5 cm, terminal lobe subulate, 3-4.5 cm; ovules 1(-3) on each side of distal part of stalk, glabrous. Seeds 2(-4), orange, becoming dark brown, often obovoid, compressed, 4.5-6 × 4-4.7 cm; sclerotesta smooth, sarcotesta with a mixed, thick, fleshy, fibrous layer. Pollination Jun-Jul, seed maturity Feb-Mar.
Dry, open thickets in limestone mountains, red soil in sparse monsoon forests; 1000-1800 m. S Yunnan [Bangladesh, Bhutan, Cambodia, NE India, Laos, Myanmar, Nepal, Sikkim, Thailand, Vietnam]
A vulnerable species in China. Cultivated as an ornamental in S Yunnan and elsewhere in SE Asia. Chinese plants have been misidentified as C. rumphii Miquel (e.g., in FRPS), which occurs only in Indonesia and Papua New Guinea.