Symphyotrichum oblongifolium (Nutt.) G.L. Nesom

Aromatic Aster


CC = 6
CW = 5
MOC = 49

© SRTurner

Family - Asteraceae/Astereae

Habit - Perennial forb, with a somewhat woody, horizontal rootstock, often also with 1 or more slender and longer-creeping, rhizomatous branches.

Stems - Usually several, to 80 cm, commonly with several ascending to spreading branches above the midpoint, sparsely to moderately pubescent with short, spreading hairs, progressively more glandular toward the tip, the branches and apical portion of the main stem usually with dense, stalked glands.

Symphyotrichum_oblongifolium_stem.jpg Upper stem.

© SRTurner

Symphyotrichum_oblongifolium_stem2.jpg Lower stem.

© DETenaglia

Leaves - Basal and lower stem leaves absent at flowering, sessile or nearly so, the blade 2-6 cm long, 0.5-1.5 cm wide, oblanceolate, tapered at the base, rounded or angled to a usually bluntly pointed tip, the margins entire and hairy, the surfaces usually sparsely pubescent, also usually sparsely glandular. Median and upper stem leaves often relatively numerous, more or less progressively smaller toward the stem tip, sessile, not clasping the stem, the blades 1-10 cm long, narrowly oblong-lanceolate to narrowly lanceolate, narrowed or rounded at the sometimes slightly expanded base, angled or tapered to a bluntly or sharply pointed tip, the margins entire, hairy, the surfaces moderately to densely hairy, those of the upper leaves also with moderate to dense, stalked glands.

Symphyotrichum_oblongifolium_leaves2.jpg Stem and leaves.

© SRTurner

Symphyotrichum_oblongifolium_leaf1.jpg Leaf adaxial.

© SRTurner

Symphyotrichum_oblongifolium_leaf2.jpg Leaf abaxial.

© SRTurner

Inflorescence - Open panicles, often with numerous heads, sometimes with solitary heads or small clusters at the tips of short to long branches, the heads appearing mostly long-stalked, the bracts few to several, 0.3-0.8 cm long, linear to narrowly oblong.

Symphyotrichum_oblongifolium_inflorescence.jpg Inflorescence.

© SRTurner

Heads - 2-3 cm in diameter at flowering. Involucre 5-8 mm long, the bracts in 4-6 subequal to somewhat unequal, overlapping series. Involucral bracts mostly narrowly oblong to narrowly oblong-oblanceolate, all but the inner series angled or short-tapered to the sharply pointed tip, the tip spreading or reflexed, those of the outer series often more or less leaflike, the surfaces and margins with relatively dense, stalked glands.

Symphyotrichum_oblongifolium_heads.jpg Flowering heads.

© SRTurner

Symphyotrichum_oblongifolium_heads2.jpg Flowering heads

© SRTurner

Symphyotrichum_oblongifolium_involucres.jpg Involucres.

© SRTurner

Florets - Ray florets 15-35 in usually 1 or 2 series, the corollas well developed, 9-15 mm long, purple or rarely pink. Disc florets 30-50, the corollas 4.5-6.0 mm long, the slender portion of the tube usually slightly shorter than the slightly expanded apical portion, the lobes 0.4- 0.7 mm long, 18-25 percent of the total length of the expanded portion. Pappus bristles 4-6 mm long, mostly pale orangish brown to light tan.

Symphyotrichum_oblongifolium_florets.jpg Ray florets with extended styles.

© SRTurner

Symphyotrichum_oblongifolium_florets2.jpg Disk florets.

© SRTurner

Fruits - Achenes 2.0-2.5 mm long, with 7-10 longitudinal ribs, purplish brown to brown, sparsely hairy.

Flowering - July - November.

Habitat - Limestone glades, bluff escarpments, rocky prairies, open slopes. Also cultivated.

Origin - Native to the U.S.

Lookalikes - Several other asters.

Other info. - This showy aster is common in many parts of Missouri, less so in the northern half of the state. Within the continental U.S. its range includes a broad swath of the Midwest and Plains states. The glandular involucres and usually branched habit are strong clues to the identity. The stems usually bear numerous smallish leaves. Bruised foliage is aromatic, leading to the common name.

The branched, bushy habit of this species is unlike most other asters. Well-established plants will typically bear dozens of heads. This is particularly true of cultivars which are popular garden ornamentals. Its value in this application is enhanced by its drought tolerance. As with many asters, the color of the ray ligules can vary toward pinkish or bluish shades of purple.

Photographs taken in Eminence, MO., 10-12-03, and at Tall Grass Prairie National Preserve, KS., 9-23-06 (DETenaglia); also at Shaw Nature Reserve, Franklin County, MO, 10-23-2011, Cuivre River State Park, Lincoln County, MO, 9-29-2012, and Little Lost Creek Conservation Area, Warren County, MO, 10-10-2020 (SRTurner).