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Published In: Sertum Anglicum 16, t. 35, 36. 1788[1789]. (Jan 1789) (Sert. Angl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 7/9/2009)
Acceptance : Accepted
Project Data     (Last Modified On 8/10/2009)


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13. Boltonia L’Hér. (false aster) (Morgan, 1967)

Contributed by Sarah M. Tofari

Plants robust perennial herbs, fibrous-rooted, with rhizomes or basal offshoots, sometimes somewhat woody at the base. Stems solitary or few, 40–250 cm long, erect or ascending, with usually numerous ascending to loosely ascending branches above the basal 1/3, with prominent pale ridges, glabrous. Basal leaves absent at flowering, narrowly oblanceolate to oblong-obovate. Stem leaves mostly sessile, progressively reduced toward the stem tip, the blades oblanceolate to elliptic or linear, bluntly to sharply pointed at the tip, tapered to long-tapered at the base, the margins entire or minutely toothed, the surfaces glabrous. Inflorescences panicles, these often large and highly branched, flat-topped or more commonly rounded, the heads solitary at the branch tips, the branches with numerous linear to linear-lanceolate or linear-elliptic, leaflike bracts. Heads radiate, not sticky or resinous. Involucral bracts in 2–5(6) unequal to subequal, overlapping series, linear to lanceolate, oblanceolate, or spatulate, the tip ascending, differentiated into a somewhat thickened, green to yellowish green central band, and narrow to relatively broad, pale margins, these occasionally minutely toothed, glabrous. Receptacle hemispherical or conical, sometimes with inconspicuous, minute, irregular ridges around the concave attachment points of the florets. Ray florets 20–60, pistillate, the corolla white or less commonly pinkish- to purplish-tinged. Disc florets numerous (50–400 or more), perfect, the corolla yellow, not persistent at fruiting. Pappus a short, irregular crown of 4–10(–12) minute awns or narrow scales and 2(–4) longer (0.5–2.0 mm) awns, the longer awns often absent in the ray florets and sometimes also in the disc florets. Fruits of 2 types; those developing from the disc florets wedge-shaped to obovate in outline, relatively strongly flattened, broadly rounded or angled to shallowly notched at the tip, the margins winged, the surface and margins often minutely hairy, tan to grayish brown with lighter wings; fruits developing from ray florets more or less wedge-shaped, 3-angled, with 3 narrow wings. Five species, U.S., Canada.

Boltonia species superficially resemble Erigeron, but recent molecular and morphological studies (Noyes and Rieseberg, 1999; Nesom and Noyes, 2000) have suggested that Boltonia and two other small groups formerly associated with Erigeron are more closely related to Symphyotrichum and some other North American genera within the tribe Astereae. The two close relatives of Boltonia are the genera Chloracantha G.L. Nesom et al., which ranges from Central America to the southwestern United States, and Batopilasia G.L. Nesom & Noyes, which is found only in a small area of southwestern Chihuahua, Mexico.


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1 1. Leaf bases decurrent below the attachment point as wings of green tissue along the stem ridges ... 2. B. DECURRENS

Boltonia decurrens
2 1. Leaf bases not decurrent

3 2. Flower heads relatively large, the disc usually 614 mm in diameter at flowering, the ray corollas 715 mm long; lower and median leaves with the blades oblanceolate to elliptic; pappus awns 0.52.0 mm long, mostly well developed ... 1. B. ASTEROIDES

Boltonia asteroides
4 2. Flower heads relatively small, the disc 36 mm in diameter at flowering, the ray corollas 58 mm long; lower and median leaves with the blades linear to sometimes oblanceolate; pappus awns 0.30.7 mm long, mostly poorly developed ... 3. B. DIFFUSA Boltonia diffusa
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