Low-growing, spreading plants for edgings, rock gardens, ground covers, pattern plantings. All kinds have attractive year-round foliage and clusters of small, white, pink, or rose-purple flowers in spring. Seldom browsed by deer. Give good drainage.
A. alpina. MOUNTAIN ROCKCRESS. Native to mountain elevations of Europe. Low, tufted, rough-hairy plant 410 in. high, 2 ft. wide. Produces white flowers in dense, short clusters. Selection 'Rosea' bears pink flowers; 'Variegata' has yellow-edged green leaves.
A. a. caucasica (A. albida). WALL ROCKCRESS. Native from Mediterranean region to Iran. This plant is a dependable old favorite. Forms mat of gray-green leaves to 6 in. high, 112 ft. wide. White flowers almost cover plant during bloom season. Excellent ground cover and base planting for spring-flowering bulbs such as daffodils and 'Paper White' narcissus. Provide some shade in hot climates. 'Variegata' has gray leaves with creamy white margins; 'Flore Pleno' is double flowered; 'Rosabella' and 'Pink Charm' bear pink blooms.
A. procurrens. WHITE ROCKCRESS. Zones US, MS; USDA 6-7. Native to southeastern Europe. Creeping plant with 112-in. leaves and white flowers clustered on 4- to 12-in. stems. Over time, spreads widely.
A.x sturii. Dense, fist-size cushions of small, bright green leaves eventually grow into small mats bearing clusters of white flowers on 2- to 3-in. stems. Some consider this species among the finest rock garden plants.