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Published In: Journal de Physique, de Chimie, d'Histoire Naturelle et des Arts 88: 195–196. 1819. (Mar 1819) (J. Phys. Chim. Hist. Nat. Arts) Name publication detailView in Biodiversity Heritage Library
 

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2. Tribe Astereae Cass.

(Nesom, 2000)

Plants annual, biennial, or perennial herbs (sometimes woody elsewhere), sometimes from a woody rootstock, rarely aromatic, the sap not milky. Stems not spiny or prickly. Leaves alternate (rarely opposite elsewhere), sometimes also in a basal rosette, sessile to long-petiolate, not spiny or prickly. Leaf blades entire to lobed, the venation pinnate or less commonly with 3 main veins. Inflorescences mostly terminal panicles, sometimes reduced to clusters of heads, or the heads solitary at the branch tips. Heads discoid or radiate. Involucre of 2 to more commonly several series of bracts, not spiny or tuberculate. Receptacle flat to slightly convex or less commonly hemispherical to conical, naked (rarely with a few chaffy bracts toward the margin in Solidago), sometimes minutely concave around the base of each floret and with irregular low ridges between them, minutely hairy in Euthamia. Ray florets (when present) pistillate or less commonly sterile, sometimes inconspicuous, the corolla sometimes very short, white, pink, purple, blue, or yellow. Disc florets all perfect or the outermost sometimes pistillate, the corolla yellow or less commonly white (in some species turning reddish purple after pollen has been shed), the 4 or more commonly 5 lobes spreading to ascending. Pappus most commonly of numerous capillary bristles, these usually with inconspicuous, short barbs, less commonly with an additional outer series of much shorter bristles or scales, in a few genera only of short awns or scales, rarely absent, when present more or less persistent at fruiting. Stamens with the filaments not fused together, the anthers fused into a tube, each tip without an appendage, each base truncate or with a pair of short lobes. Style branches somewhat flattened, each with a stigmatic line along each inner margin, the sterile tip relatively long and tapered, often with dense, minute hairs, at least on the outer surface. Fruits rarely somewhat dimorphic (the outer series then thicker-walled and with different surface ornamentation), often somewhat flattened, oblong-obovoid to slightly wedge-shaped in profile, often somewhat ribbed, not beaked. About 175–200 genera, 2,800–3,020 species, worldwide.

The Astereae contain a number of genera that are commonly cultivated as garden ornamentals, including Aster, Bellis L. (English daisy), Boltonia, and Solidago. As in other tribes of Asteraceae, the current trend among students of the Astereae has been to divide the larger genera taxonomically into smaller taxonomic segregates reflecting monophyletic lineages. For example, users of this volume should not be shocked to see that Missouri now only has one species in the genus Aster (a garden escape; see below) and that all of the native asters have been classified into four other genera.

Users should note that Solidago bicolor L. (silverrod), a species that may potentially occur in Missouri but has not yet been confirmed for the state, will not key correctly in the key to genera below. This species is unusual in the genus in having yellow disc corollas and white (or pale cream-colored) ray florets. The plants otherwise resemble those of S. hispida; see that species further discussion.

 

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1 1. Heads radiate, the ray florets with yellow corollas (in a few cases, the corolla may be darker-tinged on the undersurface)

2 2. Pappus of less than 10 scales or awns, sometimes absent or only a minute, toothed crown in ray florets

3 3. Involucre 615 mm long; ray florets 1445, the corolla 820 mm long ... 21. GRINDELIA

Grindelia
4 3. Involucre 35 mm long; ray florets 715, the corolla 47 mm long

5 4. Disc florets staminate (style branches not separating at flowering; florets not maturing into fruits), their pappus of 59 awns or slender scales, these about as long as the corolla, fused toward the base ... 9. AMPHIACHYRIS

Amphiachyris
6 4. Disc florets perfect, their pappus a minute (less than 0.2 mm) crown or rarely an irregularly toothed (scalelike) ring, much shorter than the corolla ... 22. GUTIERREZIA

Gutierrezia
7 2. Pappus of numerous capillary or occasionally stouter bristles, sometimes additionally with an outer ring of short bristles

8 5. Pappus of the disc florets of 2 types, the inner series of capillary bristles much longer than the outer series

9 6. Ray florets lacking a pappus ... 23. HETEROTHECA

Heterotheca
10 6. Ray florets with a well-developed pappus

11 7. Plants annual, with usually short, stout taproots ... 14. BRADBURIA

Bradburia
12 7. Plants perennial, often with taproots but often also producing rhizomes, the rootstock often somewhat woody ... 23. HETEROTHECA

Heterotheca
13 5. Pappus of the disc florets more or less uniform, not differentiated into distinctly different inner and outer series (some of the bristles sometimes slightly shorter but then more or less intermingled with the longer ones)

14 8. Involucre 1015 mm long; ray florets 2545, the corolla 1020 mm long ... 21. GRINDELIA

Grindelia
15 8. Involucre 29 mm long; ray florets (2)325(35), the corolla 0.57.0 mm long

16 9. Leaf blades all linear to narrowly linear, the margins all entire, one or both surfaces dotted with impressed resin glands (these sometimes faint); receptacle minutely hairy around the base of each floret; ray florets usually more numerous than the disc florets ... 20. EUTHAMIA

Euthamia
17 9. Leaf blades not all linear (some or all of the leaves shaped differently) and/or at least some of the blades few- to many-toothed along the margins, lacking impressed dots or resin glands (except in S. odora); receptacle not hairy, often with irregular low ridges between the florets; ray florets often fewer than the disc florets ... 25. SOLIDAGO

Solidago
18 1. Heads discoid (check carefully to rule out the presence of relatively short, inconspicuous ray florets) or, if radiate, then the ray florets with the corollas white, pink, purple, or blue

19 10. Disc florets with the corollas white, fading to light brown with age ... 25. SOLIDAGO

Solidago
20 10. Disc florets with the corollas yellow, sometimes turning reddish purple after pollen has been shed or fading to brown with age

21 11. Pappus of disc florets of less than 10 scales and/or awns, sometimes absent or only a minute ridge or crown

22 12. Heads completely discoid, resinous-sticky, especially when young ... 21. GRINDELIA

Grindelia
23 12. Heads radiate (the ray florets sometimes relatively small and inconspicuous), not resinous or sticky

24 13. Plants robust perennials, fibrous-rooted, with rhizomes or basal offshoots; stems 40250 cm long ... 13. BOLTONIA

Boltonia
25 13. Plants annual, taprooted, lacking rhizomes and basal offshoots; stems 335(50) cm long

26 14. Involucre 58 mm long, the bracts in 4 or 5 unequal, overlapping series; ray florets 1845 ... 10. APHANOSTEPHUS

Aphanostephus
27 14. Involucre 2.55.0 mm long, the bracts in 2 or 3 unequal or subequal, overlapping series; ray florets 522

28 15. Receptacle flat or slightly convex; pappus of 5 nearly transparent scales 0.21.8 mm long, these often alternating with 5 bristlelike awns 13 mm long ... 15. CHAETOPAPPA

Chaetopappa
29 15. Receptacle hemispherical to conical; pappus essentially absent, represented by a faint line or minute ridge ... 12. ASTRANTHIUM

Astranthium
30 11. Pappus of at least the disc florets of relatively numerous (sometimes as few as 8 in Erigeron) capillary or occasionally stouter bristles, sometimes additionally with an outer ring of short bristles or scales

31 16. Heads discoid or, if radiate, then the ray florets with inconspicuous corollas that are shorter than to slightly longer than the pappus and disc corollas

32 17. Involucre 511 mm long ... 26. SYMPHYOTRICHUM

Symphyotrichum
33 17. Involucre 25 mm long

34 18. Perfect disc florets relatively few (less than 30), the head consisting mostly of pistillate ray florets with very short corollas, the strap-shaped portion sometimes reduced to a short fringe at the tip of a slender tube; florets all with a well-developed pappus ... 16. CONYZA

Conyza
35 18. Perfect disc florets relatively numerous (more than 250), more numerous than the pistillate ray florets, these lacking or more commonly fewer than 100 (but with very short corollas) in 1(2) marginal series; pistillate (outermost) florets with a pappus of reduced bristles and/or scales that are noticeably shorter than the bristles of the other florets ... 18. ERIGERON

Erigeron
36 16. Heads radiate, the ray florets with conspicuous corollas that are noticeably longer than the pappus and disc corollas

37 19. All or most of the basal and lower stem leaves long-petiolate and with the blade truncate to cordate at the base

38 20. Inflorescences relatively short and broad in outline, flat-topped or shallowly dome-shaped, the bracts along the branches relatively few and more or less leaflike; outermost involucral bracts 12 mm wide and mostly 1.53.0 times as long as wide; plants with long-creeping rhizomes ... 19. EURYBIA

Eurybia
39 20. Inflorescences usually relatively elongate (occasionally short and broad in poorly developed or young plants), not appearing flat-topped or dome-shaped, the bracts along the branches often (but not always) relatively numerous and conspicuously more slender than the leaves; outermost involucral bracts 0.20.8 mm wide and mostly 48 times as long as wide; plants with the rhizomes often (but not always) relatively short and stout or absent ... 26. SYMPHYOTRICHUM

Symphyotrichum
40 19. None of the leaves both long-petiolate and with the blade truncate to cordate at the base

41 21. Basal leaves very robust, mostly 2550 cm long and 310 cm wide, usually persistent at flowering ... 11. ASTER

Aster
42 21. Basal leaves much smaller, often withered or absent at flowering

43 22. Involucral bracts in 1 or 2 series, all similar in length or less commonly the outer series somewhat shorter, the green central portion of each bract relatively uniform from the base to the tip and not conspicuously broadened toward the tip; style branches with the sterile tip (beyond the stigmatic lines) 0.10.3 mm long, lanceolate to broadly triangular; plants mostly flowering from spring through early summer ... 18. ERIGERON

Erigeron
44 22. Involucral bracts in 39 series, mostly unequal in length with the outer series usually noticeably shorter (but subequal in Eurybia hemispherica and some species of Symphyotrichum), the green central portion of each bract absent or very slender toward the base and broadened abruptly; style branches with the sterile tip (beyond the stigmatic lines) (0.2)0.30.5 mm long, linear to lanceolate; plants mostly flowering from late summer through autumn

45 23. Pappus of 2 types, the inner 1 or more series of numerous longer bristles, the outer series of few to many much shorter bristles

46 24. Leaves broadly to narrowly elliptic or lanceolate-elliptic; involucre 35 mm long; innermost pappus bristles usually slightly broadened toward the tip (narrowly club-shaped); rays with the corolla white ... 17. DOELLINGERIA

Doellingeria
47 24. Leaves all linear to linear-oblanceolate; involucre 69 mm long; innermost pappus bristles all tapered toward the tip; rays with the corolla lavender to purple (rare, white-flowered plants may be found in Missouri in the future) ... 24. IONACTIS

Ionactis
48 23. Pappus of 1 or more series of bristles that are all of similar length (the outermost bristles may be slightly shorter)

49 25. Involucre 912 mm long; leaves linear to linear-lanceolate; innermost pappus bristles usually slightly broadened toward the tip ... 19. EURYBIA

Eurybia
50 25. Involucre 2.58.0 mm long or, if longer, then all or at least some of the leaves lanceolate to oblanceolate or broader; pappus bristles all tapered toward the tip ... 26. SYMPHYOTRICHUM Symphyotrichum
 
 
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