Symphyotrichum lanceolatum (Willd.) G.L. Nesom

Tall White Aster


CC = 3
CW = -3
MOC = 75

© SRTurner

Family - Asteraceae/Astereae

Habit - Perennial rhizomatous forb, somewhat colonial.

Symphyotrichum_lanceolatum_roots.jpg Roots and rhizomes.

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Stem - To 1.5 m, usually solitary, usually branched above the midpoint, sparsely to moderately pubescent above, the hairs usually in longitudinal lines, usually glabrous toward the base.

Symphyotrichum_lanceolatum_stem.jpg Stem.

© SRTurner

Leaves - Lowermost leaves usually wilted at flowering, sessile or with a short, poorly differentiated petiole, the blade 1-8 cm long, 0.5-2.0 cm wide, oblanceolate, tapered at the base, angled to a pointed tip, the margins with spreading or antrorse hairs and usually toothed or scalloped, the surfaces glabrous. Upper stem leaves often somewhat reduced, sessile, sometimes slightly expanded but not clasping the stem, the blades 1-14 cm long, linear to broadly oblanceolate, the margins entire or sparsely toothed, otherwise similar to the lower stem leaves.

Symphyotrichum_lanceolatum_leaf1.jpg Leaf adaxial.

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Symphyotrichum_lanceolatum_leaf2.jpg Leaf abaxial.

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Inflorescence - Terminal panicles, usually leafy (variety dependent), the heads appearing mostly short stalked and usually oriented in various directions, the bracts along the ultimate branches 0.2-1.0 cm long, more or less leaflike, linear or narrowly oblong-lanceolate, somewhat shorter than the adjacent foliage leaves.

Symphyotrichum_lanceolatum_inflorescence.jpg Inflorescence.

© SRTurner

Heads - Mostly 1.0-2.5 cm in diameter (including the extended ray corollas) at flowering.

Symphyotrichum_lanceolatum_heads.jpg Heads.

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Involucre - Involucre 3-7 mm long, cup-shaped to slightly bell-shaped, the bracts in 3-5 unequal, overlapping series. Involucral bracts linear-lanceolate to narrowly oblong-oblanceolate, angled or tapered at the usually sharply pointed tip, lacking a bristlelike point at the ascending tip, the outer surface glabrous or sparsely hairy, the margins often slightly irregular and sparsely hairy.

Symphyotrichum_lanceolatum_involucre.jpg Involucre.

© SRTurner

Florets - Ray florets 20-45 in usually 1 or 2 series, the corollas well developed, 5-12 mm long, white or nearly so. Disc florets 15-40, the corollas 3-6 mm long, the slender portion of the tube noticeably shorter than the slightly expanded apical portion, the lobes 0.7-1.2 mm long, 30-45 percent of the total length of the expanded portion. Pappus bristles 3-6 mm long, white or off-white.

Symphyotrichum_lanceolatum_disks.jpg Disks and rays.

© SRTurner

Flowering - August - October.

Habitat - River floodplains, mesic or bottomland forests, margins of ponds and sloughs, ditches, roadsides, open disturbed areas.

Origin - Native to the U.S.

Lookalikes - Other small white asters, especially S. lateriflorum and S. ontarionis.

Other info. - This attractive white aster occurs across Missouri as well as most of North America. It is particularly prevalent in or near floodplain regions of the large rivers. It is tolerant of disturbance and can often be found in wet cropland swales and along trail margins.

There are several white asters in Missouri and they can be hard to differentiate without detailed examination. A distinguishing character of this species is its very smooth leaves, which are normally completely glabrous except on the margins. The leaf surfaces are almost balloon-like in their smooth texture. At least the upper leaves are also sessile and tapered at the base. Yatskievych recognized three varieties in Missouri, differing subtly in leaf shape, size of involucre and disk corollas, and inflorescence leafiness. The photographs above are of var. latifolium.

Photographs taken near Dutzow, Franklin County, MO, 10-17-2019 (SRTurner).