Baptisia abberans x alba Purple Smoke - Lupin indigo, Baptisie, Faux indigo, Podalyre

The Baptisia 'Purple Smoke', or false indigo, is distinguished by long clusters of flowers in shades of purplish violet and smoky blue-mauve, borne on anthracite-grey stems that are almost black. This unusual colouring is accompanied by fine, grey-green foliage that clothes a broad, rounded clump. This robust perennial from North America takes a little time to establish, but it lives for many years with very little care. Its deep root system allows it to withstand drought well once established. It is also one of the few baptisias commonly cultivated that tolerates chalky (alkaline) soil.

The baptisia belongs to the Fabaceae family, like peas, lupins and wisteria. It is a herbaceous and deciduous perennial: its stems emerge from the rootstock in spring and then dry up in winter. Species of the genus Baptisia grow naturally in meadows, clearings and dry woodlands of North America, sometimes on poor, stony ground. 'Purple Smoke' was discovered in the early 1990s among spontaneous seedlings cultivated at the North Carolina Botanical Garden. Rob Gardner, then curator of the native plant collections, selected it for the colour of its stems and flowers. The Botanical Garden and Niche Gardens nursery introduced it in 1996. It is a hybrid between Baptisia aberrans and B. alba. The first parent passed on its small leaves and the smoky violet colour of its flowers, while the second accounts for its dark stems and grey-green foliage. The plant establishes slowly during the first two or three years, as it develops a thick, deep taproot. It then takes the form of a generous clump, 1 to 1.20m tall, potentially exceeding 1.50m in width after several years. The leaves are divided into three small leaflets, narrower than those of many other baptisias. The inflorescences, 35 to 45 cm long, gather greyish-violet pea flowers, marked with a more purplish eye. They open progressively from the base to the top between May and June. The flowering period extends over three weeks, then gives way to cylindrical pods that turn brown as they ripen. The flowers are visited by bees and butterflies. In the trial conducted by the Mt. Cuba Center, 'Purple Smoke' scored 4.7 out of 5 and was among the top ten selections tested. 

In a large, sunny border, you can pair Baptisia 'Purple Smoke' with the pale pink spikes of Linaria purpurea 'Canon J. Went', the blue-mauve flowers of the shrubby lavatera 'Blue Bird' and the stately spires of mullein 'Southern Charm'. The broom 'Hollandia', with its cream, pink and cherry-red flowers, can form a light backdrop. These plants offer successive flowering periods that animate the border from late spring to summer. Grasses such as Sporobolus heterolepis and Schizachyrium scoparium 'Blaze' also have the stature needed to compose a large border with the Baptisia and share its preference for sun, well-drained soil and a certain summer dryness.