Trunk to 25 m. tall, almost always ventricose, to 80 cm. in diameter. Leaves 16 – 23 in the crown; petiole and sheath 170 – 237 cm. long; petiole 7.8 – 9.2 cm. wide at midpoint, robust, yellow-green along the whole length, margins with small serrate black teeth, 0.1 – 0.85 cm. long; petiole spines extending along the margin of the first leaflet; costa 77 – 82 cm. long; adaxial hastula conspicuous, to 1.5 cm., abaxial hastula rudimentary; lamina radius to 100 cm. maximum, dense indumentum on the ribs of some immature leaves; leaflets 102 – 132, 4.2 – 7.9 cm. wide, apices acute and entire or splitting longitudinally with age, shortest leaflet 68 – 83 cm. long, leaf divided to 61 – 83 cm.; commissural veins 10 – 14 per cm., leaf anatomy isolateral. Staminate inflorescences branched to two orders, upper subtending branches terminating in 1 – 3 rachillae; rachillae green-brown and catkin-like, 30 – 44 cm. long, 2.3 – 3.3 cm. in diameter, usually with a mamilliform apex; rachilla bracts form pits that contain a cincinnus of 8 – 12 staminate flowers. Pistillate inflorescences spicate; flower-bearing portion 76 – 90 cm. long with 7 – 15 flowers arranged spirally. Staminate flowers 0.4 – 0.7 cm. long, exserted individually from the pits, bracteoles 0.8 × 0.5 cm.; calyx 0.5 × 0.2 cm., shallowly divided into three sepals, petals 0.2 × 0.1 cm.; stamens 6 with very short filaments, 0.02 × 0.04 cm, anthers, 0.14 × 0.1 cm.; pistillode minute. Pollen monosulcate, elliptical, 46 – 65 mm. long, aperture 38 – 52 mm. long, polar axis 42 – 54 mm. long; tectum perforate, sparsely covered with supratectal gemmae. Pistillate flowers 3.5 × 3 cm., bracteoles 2 cm. in diam., sepals 2 × 2 cm., and petals 1.5 × 1.5 cm. Fruits massive, 25 – 35 × 7 – 18.5 cm., ovoid with a somewhat pointed apex; fragrant and yellowish green at maturity; produced inside persistent perianth segments; pyrenes 1 – 2(– 3), 8.7 – 12.1 cm. × 8.3 – 12.3 cm. × 6.3 – 7.5 cm., unlobed or somewhat bilobed; some pyrenes with one or two external longitudinal furrows; internal flanges absent; an external, longitudinal crest is common. (R.P. Bayton. 2007)/Palmweb.