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Asteraceae Group 4
See list of 37 genera in this group-
1a. Pappus composed of capillary bristles (also with an additional series of minute, slender scales in some Erigeron, with a short, outer crown in Callistephus) [Figs. 438,468]
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2a. Plants subdioecious, each capitulum composed almost entirely of unisexual flowers; stems scaly bracteate; well-developed leaves all basal, the blades palmately lobed [Fig. 442] (in part)
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2b. Plants polygamous, each capitulum with the ray flowers unisexual and carpellate and the disk flowers bisexual; stems with leaves; leaves various, but neither all basal nor with palmately lobed blades
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3a. Rays up to 2 mm long, shorter than to scarcely exceeding the pappus, often inconspicuous in drying
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4a. Involucral bracts glabrous and eciliate; ± glabrous saltmarsh plants (in part)
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4b. Involucral bracts pubescent or ciliate or both; plants often with pubescent stems and/or leaf blades, at least with marginal cilia on the leaf blades, not occurring in saltmarshes
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5a. Involucre with 3 or 4 series of foliaceous bracts of ± equal length; style appendages acute to acuminate (in part)
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5b. Involucre with green but not at all foliaceous bracts, the bracts of similar or dissimilar length; style appendage acute to, more commonly, obtuse (in part)
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6a. Leaf blades pinnately lobed, each lobe terminating in a spine; involucral bracts ± spinulose-margined
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6b. Leaf blades entire to toothed (sometimes lobed in Callistephus), not spiny; involucral bracts without spinulose margins (though the apex sometimes with a spine tip)
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7a. Surface of ovary with minute stalked glands [Fig. 438]; capitula nodding in bud; leaves reduced in size toward the base, the lowest scale-like
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7b. Surface of ovary without glands; capitula erect in bud (spreading or sometimes nodding in Ionactis); leaves larger toward the stem base
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8a. Capitula frequently in glomerules, with 3–8 ray flowers [Fig. 451]; foliage leaves with sessile glands
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8b. Capitula usually borne singly at the ends of peduncles, with 7–100 or more ray flowers [Figs. 462,466]; foliage leaves without glands ( Oligoneuron album with obscure resin glands, and the bracteal leaves of some Symphyotrichum and Eurybia with stipitate glands)
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9a. Basal leaves gradually tapering to an elongate petiole, the blade and petiole combined commonly 30–40 cm long; involucral bracts usually with a thin anthocyanic stripe along each margin; rare escape in New England
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9b. Basal leaves shorter than 30 cm, lacking petioles, and/or abruptly contracted to a petiole; involucral bracts rarely with marginal anthocyanic stripes, anthocyanin, if present, usually distributed near the center and/or apex of the bract (rarely throughout); primarily native plants, though some species weedy
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10a. Involucral bracts in three series—the outer series foliaceous and green ± throughout, the inner series membranaceous to scarious; capitula solitary and the ends of branches, 6–8 cm in diameter; involucre double—outer series a short, membranous crown, inner series of minutely barbellate bristles
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10b. Involucral bracts variable, usually not foliaceous (except in a few Symphyotrichum); capitula solitary, in glomerules, or few to many along branches; involucre single or double, but not with an outer, membranous crown
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11a. Involucral bracts of ± equal length (sometimes with some very small bracts near the base of the involucre), green throughout or in large part, but not foliaceous; style appendage acute to, more commonly, obtuse (in part)
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11b. Involucral bracts of dissimilar lengths, usually pale at the base with an apically dilated green midzone [Figs. 462,464,466], less commonly foliaceous or anthocyanic (green throughout in Doellingeria); style appendages acute to acuminate
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12a. Pappus bristles of 2 distinctly uneven lengths—a very short outer series and 1 or 2 series of elongate bristles of nearly even length [Fig. 438]; involucral bracts neither foliaceous nor with a distinct, green apical zone [Fig. 396]
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13a. Longer series of pappus bristles thickened at the apex; involucral bracts with raised midvein, but not keeled; rays not coiling; disk flowers abruptly expanded apically; ovaries terete
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13b. Longer series of pappus bristles slender at the apex; involucral bracts somewhat keeled; rays coiling; disk flowers tubular; ovaries compressed
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12b. Pappus bristles all elongate, in 2 or 3 series of nearly even length [Fig. 468]; involucral bracts with a distinct green apical zone or entirely foliaceous in a few species (anthocyanic pigments sometimes also present) [Figs. 462,464,466]
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14a. Disk corollas white; leaf blades with sessile resin glands (these sometimes obscure); pappus bristles thickened at apex (in part)
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14b. Disk corollas yellow or becoming purple, red, or red-brown; leaf blades without sessile resin glands (though the bracteal leaves stipitate-glandular in a few species); pappus bristles slender at the apex or thickened in some Eurybia
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15b. Rays 3–30 mm long [Figs. 462,465]; capitulescence resembling a panicle or corymb or infrequently composed of 1 or few capitula; disk flowers yellow, becoming purple, red, or red-brown in age
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16a. Outer and middle involucral bracts less than 2.5 times as long as wide, rounded to obtuse at the apex, densely ciliate along the margins, with a thumbnail to rhombic shaped chlorophyllous zone at the tip [Fig. 407]; capitulescence corymb-like; pappus bristles sometimes thickened at the apex; ovary terete
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16b. Involucral bracts more than 3 times as long as wide, obtuse to acuminate at the apex, eciliate or sparingly ciliate along the margins, with a rhombic to basally tapering chlorophyllous zone at the tip or entirely foliaceous [Figs. 462,464,465]; capitulescence commonly panicle-like when well formed; pappus bristles slender at the apex; ovary compressed in most species (in part)
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1b. Pappus composed entirely of scales, awns, or a short crown, or absent
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17a. Leaves opposite (the upper may be alternate)
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18a. Leaf blades 10–30 cm long, pinnately lobed with broad lobes [Fig. 445]; disk flowers functionally staminate, the ovary abortive and with an undivided style; pappus absent (in part)
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18b. Leaf blades 2–12 cm long, simple or pinnately dissected into linear to linear-filiform segments; disk flowers bisexual with a bifid style; pappus present, at least on the disk flowers, though reduced to a tiny crown in some species (absent in Sigesbeckia)
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19a. Leaf blades pinnately dissected into numerous linear to linear-filiform segments narrower than 1.5 mm; rays 5–40 mm long; cypsela body tapering to a slender, apical beak (in part)
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19b. Leaf blades simple or infrequently with a few basal lobes in Coreopsis rosea; rays up to 13 mm long; cypsela body not taping to an elongate beak
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20a. Rays 8–13 mm long; disk 5–10 mm wide; leaf blades linear (in part)
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20b. Rays 1–2 mm long; disk 3–6 mm wide in flower; leaf blades narrow-lanceolate to ovate [Fig. 412]
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21a. Involucre biseriate and dimorphic—an outer series of longer, spreading to reflexed bracts and an inner series of shorter, erect bracts—conspicuously stipitate-glandular; leaf blades resin-dotted abaxially (in part)
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21b. Involucre uniseriate or biseriate, with none of the bracts spreading to reflexed, stipitate-glandular or not; leaf blades not resin-dotted abaxially
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22a. Disk flowers yellow; capitula with 3–6 rays [Fig. 412], commonly 5; pappus of fimbriate scales
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22b. Disk flowers white; capitula with numerous ray flowers; pappus a tiny crown
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17b. Leaves alternate throughout the stem or all basal
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23a. Receptacle with spine-like setae; lobes of disk corollas villous-tomentose; pappus composed of 6–10 conspicuously awned scales (in part)
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23b. Receptacle either naked, with scale-like chaff (though the chaff may be spinescent at the tip), or bristly; lobes of the disk corollas glabrous; pappus various, but not composed of awned scales
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24a. Receptacle chaffy, at least toward the middle [Fig. 397]
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25a. Involucral bracts herbaceous, without a scarious margin, spreading to reflexed; leaf blades simple and ± entire; chaff with a stout, spinescent tip
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25b. Involucral bracts dry, scarcely or not at all herbaceous, scarious-margined (without scarious margins in Parthenium), appressed; leaves pinnately divided (except Achillea ptarmica with simple leaves); chaff without a spine-like tip
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26a. Pappus usually composed of a pair of scales; disk flowers functionally staminate, the ovary abortive and the style undivided
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26b. Pappus absent or represented by a minute crown; disk flowers bisexual, fertile, with a bifid style
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27a. Rays 5–14 mm long, numbering 10–16 per capitulum [Fig. 376]; disk 5–10 mm wide; disk flowers yellow; capitulescence not resembling a corymb, the capitula located at the tips of branches
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27b. Rays 2–5 mm long, mostly numbering 4–10 per capitulum (up to 15 in cultivated forms of A. ptarmica); disk 2–8 mm wide; disk flowers white capitulescence resembling a corymb
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24b. Receptacle without chaff
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28a. Stems scapose, the leaves all basal; capitulescence a solitary capitulum
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28b. Stems leafy; capitulescence with multiple capitula or solitary in Arctanthemum, Arctotis, Leucanthemum, and Nipponanthemum
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29a. Pappus of disk flowers composed of 5–8 oblong to ovate, hyaline scales 0.5–4 mm long; cypsela with a conspicuous basal tuft of long, silky hairs
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29b. Pappus of disk flowers absent, a short crown, or dimorphic and composed of barbellate awns and shorter awns or flat scales; cypsela lacking a long basal tuft of silky hairs
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30a. Pappus of disk flowers composed of 2–4 long, barbellate awns and a variable number of shorter bristles or flat scales; style branches not truncate at apex, lacking an apical tuft of hairs
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31a. Leaves with simple and entire blades, not clasping the stem; pappus of 2 or 3 awns and 7–12 shorter bristles or scales
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31b. Leaves with subpalmately lobed blades, narrowed to a winged petiole, expanded at the base and clasping the stem; pappus 2–4 awns and 2–4 scales
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30b. Pappus a short crown or absent; style branches truncate and penicillate
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32a. Leaf blades twice pinnatifid, with linear to filiform ultimate segments; receptacle convex, rounded, or pointed
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33a. Receptacle conic, acute at the apex [Fig. 432]; cypsela with an oblique attachment scar near base, the body with 3–5 raised, but not wing-like, ribs, lacking apical resin glands; plants pleasantly aromatic (in part)
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33b. Receptacle dome-shaped, rounded at the apex; cypsela with basal attachment scar, the body with 3, prominently thickened and almost wing-like ribs, with apical resin glands; plants nearly inodorous
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32b. Leaf blades toothed, subpalmately lobed, or 1- to 2-times pinnatifid into oblong-elliptic to ovate primary segments; receptacle flat or low-convex
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34a. Plants subshrubs, with deciduous lower leaves, so most of the stems leaves are clustered near the apex of the shoot; leaf blades somewhat succulent, evergreen [Fig. 437]
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34b. Plants herbaceous, the leaves not clustered near the stem apex; leaf blades not succulent, deciduous
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35a. Pappus present, a short crown; capitula 6–20 mm across in life, arranged in corymb-like clusters; disk 4–9 mm wide
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36a. Leaf blades crenate-dentate, sometimes the larger with a few basal lobes, the lower blades 10–25 cm long (in part)
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36b. Leaf blades with 3–9 oblong-elliptic to ovate segments that may be again lobed, none of the blades exceeding 8 cm in length (in part)
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35b. Pappus absent (rarely some ray flowers with wall tissue prolonged to appear as a short crown in Leucanthemella and Leucanthemum); capitula 20–60 mm across in life, solitary at the tips of branches or arranged in corymb-like clusters; disk 10–25 mm wide
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37a. Ray flowers sterile, not producing fruits; leaf blades glandular-punctate; disk corolla tubes provided with resin glands
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37b. Ray flowers fertile, producing fruits; leaf blades without glandular-dots; disk corolla tubes lacking resin glands
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38a. Disk flowers compressed and winged near base; body of cypsela with 10 ribs; pericarp of cypsela with resin canals
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38b. Disk flowers neither compressed nor winged near base; body of cypsela with 5–8 ribs; pericarp of cypsela without resin canals
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39a. Leaf blades glabrous or subglabrous, the lower flabellate to spatulate, nearly or fully as wide as long; capitulescence consisting of a solitary capitulum; rays white
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39b. Leaf blades gray-pubescent, lanceolate or elongate-elliptic to ovate, clearly longer than wide; capitulescence consisting of 1 to several capitula in a corymb-like array; rays commonly yellow, pink, purple, red, or white (but other color forms also exist) (in part)
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Each photo represents one genus in this subgroup.