Recent castoffs from the genus Aster, these familiar garden perennials have an unfamiliar name. These are the New World asters, and they now have their own genus. Gardeners rely upon them for their clouds of blue, purple, pink, and white blooms in the autumn garden.
S. cordifolium (A. cordifolius). BLUE WOOD ASTER. Native to eastern North America. To 6 ft. tall, 3 ft. wide, with loose, branching clusters of inch-wide lavender flowers. Sun or light shade. 'Little Carlow', to 2 ft. high, bears a profusion of violet-blue flowers.
S. ericoides (A. ericoides). HEATH ASTER. Native to eastern North America. To 3 ft. tall and 1 ft. wide, with narrow leaves and strong horizontal branching. Profuse -in. blooms in white, pink, or blue. Plants sold as S. e. 'Monte Cassino' may actually belong to S. pringlei.
S. laeve (A. laevis). SMOOTH ASTER. Native to eastern North America. Grows to 312 ft. tall, 1 ft. wide, with smooth, mildew-free foliage and clustered 1-in. flower heads of deep purplish blue. 'Bluebird' is a superior selection to 45 ft. tall.
S. lateriflorum (A. lateri- florus). CALICO ASTER. North American native. Species grows to 4 ft. tall, 1 ft. wide. Garden selections are shorter (to 2 ft.), with profuse branching, tiny leaves and a haze of -in., purplish pink flowers. Foliage turns a coppery purplish red in early fall. 'Prince' has blackish purple stems and leaves; its blooms are white with a red center. 'Lady in Black' is a bolder version of 'Prince', with the same dark foliage and masses of tiny, red-centered white flowers; it grows 34 ft. tall. 'Coombe Fishacre' is a hybrid developed from S. lateriflorum; it produces tiny pink flowers with red centers on a plant to 23 ft. tall.
S. novae-angliae (A. novae-angliae). NEW ENGLAND ASTER. Native from Vermont to Alabama, west to North Dakota, Wyoming, and New Mexico. Stout-stemmed plant to 35 ft. tall and nearly as wide, with hairy leaves to 5 in. long. Flowers are 2 in. wide; they are violet-blue in the basic form, with selections in other blue shades, white, pink, nearly red, and deep purple. All are very tolerant of wet soils and will reseed. Two longtime favorite selections are good garden plants: 'Alma Potschke' produces salmon-pink, single blooms on 3-ft. stems from late summer to early fall; 'Harrington's Pink' produces clear pink single flowers over a long autumn season on 3- to 4-ft. stems. Another good selection is 'Purple Dome', which reaches just 1 ft. tall and has brilliant purple blooms.
S. novi-belgii. (A. novi-belgii). NEW YORK ASTER, MICHAELMAS DAISY. Native to eastern North America. To 4 ft. tall and 3 ft. wide, with full clusters of bright blue-violet flowers. Similar to S. novae-angliae but with smooth leaves. Hundreds of selections are available, varying in height from less than a foot to over 4 ft.; flower colors include white, cream, blue, lavender, purple, rose, and pink. Among the many choices are 'Persian Rose' (rose-pink) and semidouble 'Professor Anton Kippenburg' (lavender-blue), both under 1 ft. high and 1 ft. wide. Robust 'Climax' bears large sprays of single medium blue blossoms on stems to 6 ft. high.
S. oblongifolium (A. oblongifolium). AROMATIC ASTER. From the central U.S. Grows 2 ft. tall and wide, with light blue-violet, 1-in. flowers that last into late fall, unperturbed by heavy frosts. Pale green leaves are aromatic when crushed. Prefers a dry, open site; tolerates harsh conditions, including heat, cold, poor or alkaline soil, and strong winds. Selection 'October Skies' produces rich sky-blue flowers; 'Raydon's Favorite' bears bluish purple ones. 'Fanny', growing 34 ft. tall, has grayish green leaves and masses of bright purple blossoms. 'Raydon's Birthday Pink' grows upright up to 3 ft. tall.
S. patens (A. patens). LATE PURPLE ASTER. From the eastern and southeastern U.S. To 3 ft. tall, 1122 ft. wide. Prolific show of bright violet-blue, 1-in. flowers. Tolerates drought and partial shade.
S. pilosum pringlei (A. pilosus pringlei, A. pringlei). HAIRY ASTER. Eastern U.S. native known in cultivation through its selection 'Monte Cassino', a familiar florists' cut flower. Grows to 5 ft. tall and 112 ft. wide; tall, narrow stems have many short side branches set with starry, white, 34-in. flowers. This plant is often sold as S. ericoides 'Monte Cassino'.