Plants of the Eloise Butler Wildflower Garden

Stems: White Wood Aster is an erect perennial that grows from 1 to 2-1/2 feet tall. Stems tend to have a slight zigzag to them and they can be spreading or sprawling. The stem within the floral array has dense very fine hair.

Leaves are large and thin, ovate-lanceolate in shape with heart shaped bases, sharp coarse teeth on the margins and a pointed tip that usually has a twist to it. If there is any leaf hair it will be sparse. The underside may have hair, particularly along the veins. Lower leaves are on long stalks. Upper leaves will be much smaller with short stalks, sometimes stalkless. The more basal leaves will drop by flowering time.

The floral array is a loose grouping of somewhat flat-topped branched clusters (Corymbs) branching from the top part of the stem. In a corymb the flower stalks are of different length so that the flower heads form a flat-topped cluster. Several long green bracts may appear among the flowers.

The composite flowers are about one inch wide composed of two types of florets: 5 to 10+ white ray florets that are pistillate and fertile, surrounding a central disc of 12 to 19+ tubular, bisexual, fertile, yellow disc florets that turn reddish at maturity. The tubes of the florets are unusually long and the five lobes of the disc floret corolla are erect to spreading during flowering instead of forming a flat circle. The five stamens surround the style tightly and both protrude from the corolla. The rays of the ray florets can also have a lilac tinge of color. They also seem to be pointing in various directions. The phyllaries that surround the outside of the flower head number 25 to 30 in 4 to 5 series, unequal in size, are rounded to pointed in shape and are whitish with dark green tips. The inner series can have a purplish tinge. Flower head stalks and the phyllaries usually do not have any glandular hair.

Seeds are a brown dry cypsela, 2.6 to 3.8 mm long with 7 to 10 ribs and with a few fine reddish to cream colored bristles and hair for wind dispersion. Most Aster seeds normally need 30 to 60 days of cold stratification for germination.

Habitat: White Wood Aster grows from a creeping branched rhizome, which will form colonies. It prefers the drier, well drained soil of open woods in partial to full shade. Best to plant in an area where it can sprawl out as the flower clusters held above the leaves are quite showy.

Names: The species was originally named Aster divaricatus by Linnaeus in 1753, however, all the new world asters, formerly in the genus Aster, have now been reclassified, most into the genus Symphyotrichum; several, like this species, to Eurybia. The genus Eurybia is from two Greek words - eurys meaning 'wide' and baiso, meaning 'few', alluding to the few wide-spreading ray florets. The species name, divaricata, refers to the 'spreading' or 'growing in a straggling' habit. Asters in the Eurybia genus have disc florets with long tubes and funnelform to campanulate throats.

The author name for the new plant classification from 1995 - ‘G. L. Nesom’ is for Guy L. Nesom (b. 1945) American botanist who has published papers on the nomenclature of asters. He updated the work of the original author - '(L.)' which refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.

Comparisons: The most likely species to confuse with this one is it's sister in the Eurybia genus, the Bigleaf Aster, E. macrophylla. Differences are that E. divaricata has white petals with little or no lilac color, fewer floret rays per flower head, and the leaves are only on the flowering stem, whereas E. macrophylla has more lilac color, 9 to 20 rays, and does have glandular hair. The Heart-leaved Aster, Symphyotrichum cordifolium, also have similar leaves, but the flower panicle is rounded, not flattened.