Perennial evergreen herb to 1.8 m cm high, multi-stemmed, but each stem generally unbranched and biennial. Leaves alternate, clustered in loose rosette near the top of flowering stems; blades on stems linear, narrow-elliptic or oblanceolate, 40—110 mm long, 3âÂÂ13 mm wide; blades in whorl-head obovate to oblanceolate,10—55 mm long, 8—15 mm wide, green to yellow; blades in floral head fused and cup-like, 12—15 mm wide. Floral head cylindrical with 10—45 rays, 2-forked up to 3 times. Cyathia 3—4 mm wide; glands 4, notched or with 2 small horns, yellow, green or purple-brown.
Two subspecies are cultivated:
subsp. characias Stems less than 80 cm tall; glands dark reddish brown, notched, or with short horns.
subsp. wulfenii (W. Koch) A. R.-Sm., Dalmatian Spurge. Stems up to 1.8 m tall, flower spikes broader than those of subsp. characias; glands yellow, with long horns. Syn. E. wulfenii W.Koch.
Source: (2002). Euphorbiaceae. In: . Horticultural Flora of South-eastern Australia. Volume 3. Flowering plants. Dicotyledons. Part 2. The identification of garden and cultivated plants. University of New South Wales Press.