Symphyotrichum sericeum (Vent.) G.L. Nesom

Silky Aster


CC = 9
CW = 5
MOC = 28

© SRTurner

Family - Asteraceae/Astereae

Habit - Perennial forb, usually with a short, stout, cormlike rootstock, this somewhat woody, sometimes more elongate and rhizomatous.

Stems - Ascending to erect, to 70 cm, with few to several ascending to loosely ascending branches above the midpoint, ranging from glabrous or nearly so toward the base to densely pubescent with appressed, silky hairs toward the tip.

Symphyotrichum_sericeum_stem.jpg Stem and nodes.

© SRTurner

Leaves - Basal and lower stem leaves absent at flowering, sessile, the blade 1.5-5.0 cm long, 0.4-1.0 cm wide, mostly oblanceolate to oblong-elliptic, short-tapered to rounded at the base, mostly angled and with a minute, sharp point at the tip, the margins entire, the margins and surfaces moderately to densely pubescent with appressed, silky hairs (the leaves appearing silvery), the secondary veins on the leaf undersurface not visible or faint and few. Median and upper stem leaves relatively uniform, sessile, not clasping or sheathing the stem, the blades 0.7-3.0 cm long, lanceolate or elliptic, angled or rounded at the base, otherwise similar to the lower stem leaves.

Symphyotrichum_sericeum_leaves1.jpg Stem and leaves.

© SRTurner

Inflorescence - Usually solitary heads or small clusters at the branch tips, the heads appearing short-or less commonly long-stalked, the bracts similar to the adjacent foliage leaves.

Symphyotrichum_sericeum_inflorescence2.jpg Inflorescence.

© SRTurner

Symphyotrichum_sericeum_inflorescence.jpg Inflorescence.

© SRTurner

Heads - Mostly 2-3 cm in diameter at flowering. Involucre 6-10 mm long. Involucral bracts in 3-6 unequal, overlapping series, lanceolate to ovate, angled or short-tapered at the sharply pointed tip, the tip erect or ascending, the outer surface and margins densely appressed-hairy.

Symphyotrichum_sericeum_heads.jpg Heads.

© SRTurner

Symphyotrichum_sericeum_involucre.jpg Involucre.

© DETenaglia

Symphyotrichum_sericeum_flowers.jpg Flowering head.

© DETenaglia

Florets - Ray florets 10-25 in usually 1 series, the corollas well developed, 9-15 mm long, dark purple or nearly blue. Disc florets 15-35, the corollas 5-7 mm long, minutely hairy, the slender portion of the tube much shorter than the slightly expanded apical portion, the lobes 0.7-0.9 mm long, 18-22 percent of the total length of the expanded portion. Pappus bristles 5.5-7.0 mm long, often slightly longer than the disc corollas, off-white to cream-colored or tan.

Symphyotrichum_sericeum_florets.jpg Disk and ray florets.

© SRTurner

Fruits - Achenes 2-3 mm long, with 7-10 longitudinal ribs, purplish brown to brown, glabrous.

Flowering - August - October.

Habitat - Glades, upland prairies, loess hills.

Origin - Native to the U.S.

Lookalikes - Many other asters.

Other info. - This showy little species can be found mainly in the Ozarks of Missouri, and also in a few other widely scattered areas of the state. It is not a common plant, with a U.S. distribution mainly restricted to a handful of states in the upper Midwest. It is one of the more easily recognized of the asters, having silky hairs which give the leaves a distinctly silvery appearance. The glade or dry upland habitat is also a good clue. The ray flowers are typically (though not always) more purple and less bluish than those of other aster species. Sericeum means "silky." The species has quite large flowers for the overall size of the plant. It is available at nurseries which offer native plants and is richly deserving of more widespread cultivation.

Photographs taken in Eminence, MO., 10-12-03 (DETenaglia); also at Reform Conservation Area, Callaway County, MO, 9-19-2015, and Victoria Glade, Jefferson County, MO, 10-7-2020 (SRTurner).