Plants of the Eloise Butler Wildflower Garden

Stems: Silky Aster is a low-growing native perennial aster that grows to two feet tall on wiry stems that usually sprawl. Stems are greenish when new but quickly turn to a more muted reddish brown color and are covered with fine hair above the base sections. The wiry structure of the stem that at times zigzags, tends to make the plant look like a tangled mess.

Leaves: The common name comes from the distinctive leaves which are pale greenish, silky and of a silvery tint, with smooth edges, covered with a fine coat of dense hair which enhances the silver effect. They are sessile (unstalked) and semi-clasping, oblong to linear-lanceolate (narrowly broadest in the lower half) in shape. Basal leaves, which are larger, will have dropped off by flowering time. Both basal and stem leaves have a sharp pointed tip.

The floral array is a small cluster of flower heads in panicle form at the end of a branching and usually arching stem.

Flowers: The flowers are quite wide for the size of the plant, being up to 1-1/4 inches across. The composite flowers have two types of florets. The outer ray florets number 15 to 30 and have lavender to pale blue (lilac) spreading rays. These are pistillate and fertile. They surround the central disc of 25 to 35 tubular, yellow, disc florets where the tubes have long deltate lobes. The disc floret corolla turns to a more reddish-purple color at maturity, typical of asters in this genus. Disc florets are bisexual, fertile, and open from the outside edge of the cluster to the center. These have 5 stamens with reddish anthers. Stamens tightly surround the style and both are exserted from the tube when the floret opens. On each flower stalk are some green leafy bracts which grade into 3 to 5 series of overlapping phyllaries that surround the flowerhead. These are ovate in shape with spade-like dark green pointed tips and a pale green mid-line. The tips are usually spreading to reflexed. Like the leaves, they have a fine silvery hair.

Seeds are a dry 7 to 10 nerved brownish cypsela, 2 to 3 mm long, that has a small tuft of whitish to tawny hair for wind dispersion. Seeds weigh about 26,000 to the ounce. Seeds require 60 days of cold stratification for germination.

Habitat: Silky Aster is an aster of sunny dry locations (dry-mesic to dry) such as where it is located in the Upland Garden. It must have well drained soil, and it handles drought and high alkalinity well. It grows from a short rhizome and fibrous roots which can form a woody caudex.

Names: Like most new world asters, Silky Aster has undergone a series of scientific name revisions. It was once Aster sericeus. All the new world asters, formerly in the genus Aster, have now been reclassified, most into the genus Symphyotrichum. The genus name is from the Greek symphysis, for 'junction', and 'trichos', for hair and, while obscure, it was first applied by Christian Gottfried Daniel Nees von Esenbeck in the 1800s in describing the type aster for the genus. The species name sericeum, means 'silky'. The author names for the plant classification are: First to classify was ‘Vent.’ which is for Étienne Pierre Ventenat (1757-1808), French botanist who published several works about plants in French gardens including the rare plants of Malmaison. French gardens grew many species imported from the New World. His work on this species was updated by ‘G. L. Nesom’ who is Guy L. Nesom (b. 1945) American botanist who has published papers on the nomenclature of asters.

Comparisons: The lilac color ray flowers may resemble the New England Aster but the small silky leaves are not confusing with another aster species in our area but further south, S. pratense, Barrens Silky Aster, is similar in shape and flower except the leaves and phyllaries are different.