Very robust, up to ± 6 dm. tall with very stout stock up to c. 5 cm. diam.; subalpine forms sts reduced to c. 15 cm. tall. Lvs on stout petioles up to ± 10 cm. long; sheaths narrow, membr., up to c. 4 cm. long. Lamina pinnate (5)-10-20-(30) × (3)-5-10 cm., us. narrow-oblong in outline. Pinnae 5-10-(12) pairs, sessile, coriac., dark green to glaucous above, paler below, close-set, often overlapping, to rather distant; about deltoid in outline; coarsely toothed to 2-3-lobed to pinnatifid or pinnatisect (on different plants); segs 1-2 cm. × 4-5 mm., ovate-oblong to linear-lanceolate; hair-processes up to c. 4 mm. long or sts reduced to acicles. Bracts with open sheaths ± 4 cm. long, narrowed to foliaceous lamina up to c. 5 cm. long. Umbels compound, upper ones us. approximate, (3)-4-5-(10) cm. diam., on stout peduncles 4-8 cm. long; bracts foliaceous. Primary rays 15-20, very stout, grooved, unequal, up to c. 4 cm. long; involucral bracts linear to lanceolate-oblong, up to 2.5 cm. long. Secondary rays short, overtopped by broad hair-tipped involucral bracts ± 1 cm. long. Fls. c. 5 mm. diam.; calyx-lobes minute, blunt; petals white, ovate-oblong, us. only slightly incurved, ± 2.5 mm. long. Fr. ovate-oblong in outline, 3-4-(5) 3 mm.; mericarps us. 3-winged; styles slender, ± 1·5 mm. long.

2n = 22