It is a very tall, narrow plant with a stem 6–10 ft (1.8–3.0 m) high, and leaves up to 48 in (120 cm) in length and 4 in (10 cm) in width - the widest in its genus. The deciduous leaves can vary in colour from bright green to bluish-green. The inflorescence grows to 4 ft (1.2 m) in length and is covered with many deep to pale pink or white flowers, 4 cm (1.6 in) across. At the base of each flower is a brown blotch with a green keel.[3] The pedicels of the flowers are longest in those at the base of the inflorescence, decreasing in length toward its tip, while the flowers themselves, numbering some 700 to 800 per inflorescence, begin to bloom in June.[4] By the time of flowering, the leaves will usually have already shrivelled.
The Latin specific epithetrobustus means "sturdy, growing strongly" (the species is the largest of its genus).[5]
The plant was introduced from Central Asia to Europe and North America in 1874 and is popular in gardens.[6] However some may find the plant to be too tall for normal gardens.[7] It prefers sandy, well-drained soil and full sun.