Know Your Natives – Drummond’s Aster

Drummond’s aster (Symphyotrichum drummondii) of the Aster (Asteraceae) family is a herbaceous perennial with disk flowers that change color with age. Preferred habitats are partially sunny upland sites in open deciduous woodlands and woodland borders along streams and roads. This aster occurs from Texas and Alabama north to Minnesota and Pennsylvania. In Arkansas, one of 21 native asters in the genus Symphyotrichum in the state, Drummond’s aster occurs throughout the Interior Highlands and Crowley’s Ridge along with several additional scattered counties. The genus name comes from Greek words relating to “a growing together” and “hair,” based on a misconception that pappus hairs occurred in a ring in the type species, New York aster (Symphyotrichum novi-belgii). The specific epithet and common name recognizes Thomas Drummond, a Scottish botanist, who, in the early 1830s, collected specimens in Texas. Other common names include blue wood aster and hairy heart-leaf aster.

Young plants have a half-dozen or so round to oval leaves up to 2 inches long in a loose rosette. Leaves have long petioles with a central depression and with stiff ascending edges. Margins are boldly serrated. Upper surfaces are medium green and lower surfaces are lighter green. Soft dense pubescence covers the undersides of leaves while pubescence on the upper sides and along petioles is less soft and less dense.

Older plants develop new basal growth in late fall that survives into spring when plants may have one or a dozen or more terete stems in a tight clump (cespitose). Basal leaves, broadly lanceolate, form a dense mass from which stems bolt. Stems, which may reach 3 to 4 feet tall, have numerous short (6 inches) to long (18 inches) branches in the upper half as well as lower insignificant axillary branching. Stems are spindly and erect, but may lean when supporting a large inflorescence. Stems are light green in spring, possibly with purplish shading, becoming yellow-green in fall. Basal and lower cauline leaves wither as stems mature. Dead, brown, woody-like stems persist into the next growing season.

Drummond's Aster - Symphyotrichum drummondiiPhoto 1: In mid-April, multiple leafy stems of Drummond’s aster bolt from a tight root clump. Plant in lower right foreground is false aloe (Manfreda virginica).

Alternate, long petioled cauline leaves may be spaced 3 inches apart lower on stems with spacing gradually decreasing to 1 inch at base of inflorescence. Largest leaves occur in the lower half of plants where leaves may be 4 inches long and 1+ inches wide. Lower leaves have cordate bases and acuminate (long tapering) apices while higher leaves, with similar apices, have bases that become more rounded. Petioles, to 2 inches long, have narrow wings extending from leaf blade to petiole base that enhance central grooves along the petioles. Petiole and blade mid-rib form a gentle continuous arch (viewed from side), while cordate bases of leaves rise above that arch. Leaf axils below the inflorecence often produce groups (fascicles) of two or three small (to ¾ inch long and 3/8 wide) oblong to elliptic leaves with short, winged petioles. While large leaves have well-spaced shallow serrations or crenulations, margins of small leaves tend to have hardly perceptible serrations. Leaves, medium green above and lighter green below, may become a golden green late in the growing season. Lower leaf surfaces are uniformly covered by short, dense and soft pubescence, while upper surfaces have short, stiffer and less dense pubescence. Lower surfaces feel smooth; upper surfaces are slightly rough. Venation is pinnate with veins on the upper side slightly depressed and those on underside slightly expressed. Leaves within the inflorescence become increasingly smaller and narrower, with those that subtend peduncles and pedicels becoming lance shaped.

Drummond's Aster - Symphyotrichum drummondiiPhoto 2: Short dense pubescence can be seen on underside of a leaf (lower center right) and along stem and petiole (upper center). Petiole and leaf mid-rib form a gentle arch.

Drummond's Aster - Symphyotrichum drummondiiPhoto 3: Display of large cauline leaves and small axillary leaves. Upper leaf surfaces shown to left and lower surfaces to right of spindly lower stem section. Petioles of these cauline leaves are winged, regardless of leaf size. Photo: mid-October.

In mid-summer, floral branching occurs in upper portion of stems with first flowers appearing about mid-September. Inflorescences consist of a few to numerous long (6 inches), straight, spreading yet upward-trending lateral branches in open-spike style or short (2 inches) branches in a more compact panicle style. Branches have small bract-like leaves spaced ¼ inch or so apart along their entire length with uppermost leaves subtending peduncles from one to 4 inches long. Peduncles are lined with overlapping to closely spaced 1/16 inch lanceolate, ascending bracts which continue to the short pedicels from which bracts transition directly into lanceolate, pointed phyllaries. Composite flower heads, to ½ inch wide, are borne on the pedicels at and near peduncle apices. Additional minor flowering may occur directly from axils of the large cauline leaves where single peduncles bear flower heads along their upper ends. Flowering occurs in late summer into mid-fall.

Drummond's Aster - Symphyotrichum drummondiiPhoto 4: Prior to appearance of flowers, peduncles and pedicels, covered with pointed ascending bracts, appear cedar-like. Photo: early September.

Drummond's Aster - Symphyotrichum drummondiiPhoto 5: Plant at full bloom with long branches that create an open-spike style of inflorescence, as compared to a plant with short branches that would have a panicle style inflorescence.

Drummond’s aster, as with all asters in the genus Symphyotrichum, has composite flower heads consisting of seed-producing pistillate (no stamens) ray florets that surround seed-producing perfect (stamens and pistil) disk florets. Heads have 10 to 15 ray florets and a smaller number of tightly clustered disk florets.

Ray florets have narrow, white to blue ligules with rounded to slightly notched tips and claw-like (narrowed) bases. Ligules, about ¼ inch long and 1/16 inch wide, are arranged irregularly and may overlap. Short styles are topped by long, bifurcated and widely spread stigmas. Disk florets, 1/10 inch long, are tubular, with corolla tubes topped by triangular lobes which close the tube in bud but point upward at anthesis. Corollas are initially cream-yellow color, but become reddish purplish shortly after opening. Five elongate anthers, not exserted, form an erect unit that encircles a tannish style. Styles become strongly exserted and stigmas divide but remain joined at their tips. Flower heads have a flat center (receptacle) held by an involucre composed of imbricated (overlapping), lanceolate, appressed and glabrous sepal-like phyllaries. Phyllaries may have a purple tip. Color differences along phyllaries may create a subtle diamond-shaped pattern. Phyllaries, in 4 or 5 series, transition directly into the lanceolate bracts that extend down the pedicel and onto the peduncle. Inferior ovaries are topped by bristly structures (pappus).

Drummond's Aster - Symphyotrichum drummondiiPhoto 6: Corollas of disk florets change from cream-yellow to reddish-purple as florets mature. Note similar appearance of appressed phyllaries and bracts. Photo: mid-October.

Drummond's Aster - Symphyotrichum drummondiiPhoto 7: A flower spike bearing heads at various stages of bloom. Note white bifurcated stigmas of pistillate ray florets (see floret at upper-right corner). Apices of phyllaries may be purple (see left-most flower heads).

Each ray and disk floret may produce a single brown achene (technically called a cypsela–a dry one-seeded, non-splitting fruit from an inferior ovary) with tufts of white hairs (pappus) encircling the top. Achenes, about 1/10 inch long, are oblong and ridged. They are dispersed by wind.

Another blue-flowered aster species of Arkansas that has disk flowers that change from yellow to purplish, and grows in similar habitats as Drummond’s aster, is blue wood aster or heart-leaf aster (Symphyotrichum cordifolium). S. cordifolium has leaf blades that have an overall heart-shape (not just the base) and long, unwinged petioles. Leaves of Drummond’s aster have shorter winged petioles.

Article and photographs by ANPS member Sid Vogelpohl

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