A fast-growing, vigorous perennial, Melianthus major grows about 2.5 m tall, suckering and spreading to about 3.5 m as it goes. The distinctive large, smooth leaves are a light bluish-green, deeply divided, with a winged rachis, toothed leaflets, a ruffled surface and a strong, nutty odour when touched.
The leaves are placed at intervals up the thick stems. The flower spikes grow out from the tip of the stems in spring, rising up above the leaves, drawing attention with their unusual dark maroon to rusty reddish colouring.