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Asteraceae Group 6
See list of 31 genera in this group-
1a. Receptacle naked
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2a. Capitula tiny, sessile and aggregated in head-like glomerules, each with a single ray flower; involucre up to 1 mm in diameter, with usually 2 bracts; upper leaf blades sessile and often connate at the base
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2b. Capitula larger, some or all peduncled, not aggregated in glomerules, each with (1–) 3 or more ray flowers; involucre wider than 1 mm in diameter, with 3 or more bracts; upper leaf blades sessile or petioled, but not basally connate
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3a. Leaves opposite and with simple, entire blades
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3b. Leaves alternate or opposite, the blades toothed to lobed or divided (blades usually entire in Helenium and sometimes in Calendula,
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4a. Leaves opposite (at least the lower), the blades once or twice pinnately divided or -lobed; involucral bracts gland-dotted
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5a. Pappus monomorphic, composed of 10–20 scales that are cleft into 3–10 divisions or bristles at the apex; involucre biseriate—the outer series with 3–9 bracts, the inner series with 8–22 bracts
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6a. Capitula with 5–8 ray flowers; inner series of 8 distinct involucral bracts; pappus scales apically cleft into 5–10 bristles (in part)
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6b. Capitula with 10–21 ray flowers; inner series of 12–22 involucral bracts that are connate 80% or more of their length; pappus scales apically cleft into 3–5 divisions (in part)
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5b. Pappus scales dimorphic, none of which are divided at the apex into bristles; involucre either uniseriate or biseriate and then with only 2 outer bracts
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7a. Capitula with (1–) 3–8 (up to 100+ in cultivars) ray flowers, the ray 1–18 (–25) mm long; pappus of 3–7 scales—1 or 2 longer scales and 2–5 shorter scales; involucre uniseriate, bracts largely connate
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7b. Capitula with (0–) 1 ray flower, the ray 0.8–1.2 mm long; pappus of 8 scales that usually are alternately unequal; involucre biseriate, the bracts distinct
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4b. Leaves alternate, simple or 1–3 times pinnately lobed; involucral bracts not gland-dotted (except in Helenium and Hymenoxys)
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8a. Pappus a tiny crown or completely absent
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9a. Cypsela bodies tuberculate-rugose on the outer surface (i.e., the surface facing the margin of the capitulum); disk flowers functionally staminate with an abortive ovary, not producing fruit; capitula 4–7 (–10) cm wide in life
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9b. Cypsela bodies not tuberculate-rugose on any surface; disk flowers bisexual or unisexual (and then carpellate), producing fruit; capitula up to 4 (–5) cm wide in life (2.5–20 cm in diameter in Chrysanthemum)
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10a. Capitulescence consisting of (10–) 20–70 (–100) capitula in a compact, corymb-like array (in part)
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10b. Capitulescence consisting of 1–3 capitula
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11a. Herbage glabrous or nearly so; cypselas dimorphic—those of the ray flowers 3-angled with 2 or 3 wing-margins, those of the disk flowers ± cylindrical; plants annual
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11b. Herbage gray-pubescent (sometime glabrate in late season); cypselas monomorphic, angled or ribbed, but without wing-angles; plants perennial
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12a. Rays longer than 10 mm; leaf blades prominently toothed to lobed; introduced plants of settled areas (in part)
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12b. Rays up to 4 mm long; leaf blades 2- to 3-times pinnately compound; native plants of northern, ice-scoured river shores (in part)
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8b. Pappus composed of distinct awns or scales
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13a. Inner series of involucral bracts connate 80% or more of their length; pappus of apically cleft scales (in part)
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13b. Involucral bracts distinct or connate only at base; pappus of awns or simple scales
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14a. Involucral bracts resinous; pappus composed of 2–8 firm, but deciduous, awns; capitula with 25–40 rays (in part)
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14b. Involucral bracts resin-dotted; pappus composed of 5–10 lanceolate to ovate or obovate, awn-tipped scales; capitula with 5–21 rays
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15a. Involucral bracts reflexed in fruit; mature receptacles ± globose [Fig. 416]; stems winged by decurrent leaf bases (not so in H. amarum); leaf blades simple (rarely pinnately lobed in H. amarum)
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15b. Involucral bracts spreading to erect in fruit; mature receptacles hemispherical; stems unwinged; larger leaf blades usually pinnately lobed into very narrow segments
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1b. Receptacle bristly or chaffy, at least toward the margin of the capitulum
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16a. Leaves regularly alternate throughout the stem
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17a. 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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17b. Receptacle chaffy with flattened scales; lobes of disk corollas not villous-tomentose; pappus various but not composed of awned scales
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18a. Involucral bracts in 1 series, laterally compressed and enfolding a ray cypsela; receptacle chaffy only near the margin; plants aromatic, with stipitate glands (at least in the capitulescence) (in part)
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18b. Involucral bracts in 1 or more series, flat, not enfolding a ray cypsela; receptacle chaffy throughout; plants aromatic or not, but lacking abundant stipitate glands
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19a. Capitula with 20–40 ray flowers; involucral bracts dry and scarious-margined
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19b. Capitula with 2–21 ray flowers [Fig. 447]; involucral bracts herbaceous or foliaceous, commonly without scarious margins
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20a. Receptacle convex to low-conic; cypsela body with evident lateral wings (very rarely the wings lacking); leaves either auriculate-dilated at base or decurrent on the stem as conspicuous wings
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20b. Receptacle conic to columnar [Fig. 447]; cypsela body lacking wings or with narrow wing margins; leaves neither abruptly and conspicuously broadened at base nor decurrent as prominent wings
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21a. Ray flowers subtended by chaffy scales; chaff velutinous at tip; cypsela body compressed
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21b. Ray flowers not subtended by chaff; chaff not velutinous at tip; cypsela body ± quadrangular
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16b. Leaves opposite or whorled, except sometimes the upper, which are alternate [Fig. 418]
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22a. Inner involucral bracts 5- to 7-ribbed, each rib bearing 1 or 2 rows of hooked prickles 1–2 mm long, maturing into a bur in fruit; annuals with prostrate stems commonly rooting from the lower nodes
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22b. None of the involucral bracts bearing prickles or maturing as a bur; annual or perennial plants, mostly with ascending stems (except the aquatic Bidens beckii)
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23a. Leaves, at least the upper, connate-perfoliate; stem square; disk flowers unisexual and staminate, with an undivided style and abortive ovary
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23b. Leaves not connate-perfoliate; stem terete or angled; disk flowers bisexual, the style divided and the ovary fertile
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24a. Plants aquatic, with flaccid stems; leaves (except for the emersed ones) whorled, finely dissected into narrow, flaccid segments; capitulescence commonly a solitary capitulum [Fig. 380]; cypselas terete (in part)
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24b. Plants terrestrial or of wetlands, with erect stems; leaves opposite, entire or divided into broad, firmer segments; capitulescence commonly composed of 2 or more capitula; cypselas compressed, quadrangular, or ± triangular
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25a. Involucral bracts conspicuously stipitate glandular, biseriate, dimorphic—the outer longer and spreading, the inner shorter and erect; leaf blades resin-dotted abaxially (in part)
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25b. Involucral bracts not stipitate-glandular (though with sessile glands or rarely with glands on short stipes near the margins in Deinandra), arranged in 1 or more series, when biseriate the outer involucral bracts not both longer than the inner and spreading (except in some Bidens); leaf blades not resin-dotted abaxially (except in Deinandra and Heliomeris and some Helianthus)
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26a. Disk corollas densely tomentose basally; involucral bracts uniseriate
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26b. Disk corollas glabrous basally; involcural bracts in 2 or more series (in 1 series in Deinandra, but that genus with only 6 disk flowers, rather than 100+ in Guizotia)
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27a. Chaff in a single series between the ray and disk flowers; pappus composed of 5–12 lanceolate to oblong or linear scales 1–1.5 mm long
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27b. Chaff not restricted to a single series ; pappus absent, of 2–4 tooth-like scales, or of 2–4 (–5) awns that are commonly minutely barbellate; involucre with 2 or more series of bracts
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28a. Ray flowers carpellate and fertile, becoming chartaceous in fruit and persistent on the triangular cypsela [Fig. 421]
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28b. Ray flowers neutral and lacking carpels (with carpels in Heterosperma, but that genus with pinnately lobed leaves), deciduous at or before maturity of the compressed or quadrangular cypsela
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29a. Involcural bracts biseriate or triseriate, ± monomorphic [Fig. 417]; chaff of the receptacle partially enfolding the disk flowers; cypsela bodies compressed at right angles to the involucral bracts
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30a. Pappus present, of 2 narrow scales (1–) 1.2–5 mm long positioned at the principal angles and 0–4 shorter scales (note: the scales are readily deciduous); cypsela body glabrous or pubescent; leaf blades 1.2–40 cm wide, at least the larger serrate or serrulate to subentire (rarely entire) and usually 3-nerved (1-nerved in H. maximiliani)
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30b. Pappus absent; cypsela body glabrous; leaf blades 0.2–2 cm wide, entire, 1 (–3)-nerved
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29b. Involucral bracts biseriate, dimorphic [Fig. 381]; chaff flat or nearly so, not or only slightly enfolding the disk flowers; cypsela bodies compressed parallel to the involucral bracts
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31a. Cypsela body tapering to a slender, apical beak; leaf blades pinnately lobed or dissected into linear or linear-filiform segments up to 1.5 (–3) mm wide (lanceolate an up to 5 mm wide in the rare introduction Cosmos sulphureus); capitula usually with 3–20 disk flowers
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32a. Ray flowers 1–3, with rays usually 1–2 mm long; disk flowers 3–10; leaf blades 1–4 cm long
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32b. Ray flowers usually 8, with rays 15–50 mm long; disk flowers 10–20; leaf blades 5–12 (–25) cm long (in part)
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31b. Cypsela body not terminated by a beak; leaf blades simple, lobed, or divided into linear to ovate segments mostly wider than 1.5 mm (narrower in a few Coreopsis); capitula with (7–) 12–150+ disk flowers
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33b. Pappus of 2 short, tooth-like scales or none; cypsela wing-margined; outer involucral bracts ± herbaceous (in part)
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Each photo represents one genus in this subgroup.