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Asteraceae Group 6

See list of 31 genera in this group
    • 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
    • 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
  • 1b. Receptacle bristly or chaffy, at least toward the margin of the capitulum
    • 16a. Leaves regularly alternate throughout the stem
      • 17a. Receptacle with spine-like setae; lobes of disk corollas villous-tomentose; pappus composed of 6–10 conspicuously awned scales (in part)
      • 17b. Receptacle chaffy with flattened scales; lobes of disk corollas not villous-tomentose; pappus various but not composed of awned scales
        • 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)
        • 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
    • 16b. Leaves opposite or whorled, except sometimes the upper, which are alternate [Fig. 418]
      • 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
      • 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)
        • 23a. Leaves, at least the upper, connate-perfoliate; stem square; disk flowers unisexual and staminate, with an undivided style and abortive ovary
        • 23b. Leaves not connate-perfoliate; stem terete or angled; disk flowers bisexual, the style divided and the ovary fertile
          • 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)
          • 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
            • 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)
            • 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)
              • 26a. Disk corollas densely tomentose basally; involucral bracts uniseriate
              • 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)
                • 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
                • 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
                  • 28a. Ray flowers carpellate and fertile, becoming chartaceous in fruit and persistent on the triangular cypsela [Fig. 421]
                  • 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
                    • 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
                      • 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)
                      • 30b. Pappus absent; cypsela body glabrous; leaf blades 0.2–2 cm wide, entire, 1 (–3)-nerved
                    • 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
                      • 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
                        • 32a. Ray flowers 1–3, with rays usually 1–2 mm long; disk flowers 3–10; leaf blades 1–4 cm long
                        • 32b. Ray flowers usually 8, with rays 15–50 mm long; disk flowers 10–20; leaf blades 5–12 (–25) cm long 
 (in part)
                      • 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
                        • 33a. Pappus of 2–6 awns, these usually retrorsely barbellate (rarely antrorsely barbellate or smooth or absent) [Figs. 381,382,383]; outer involucral bracts foliaceous in most species 
 (in part)
                        • 33b. Pappus of 2 short, tooth-like scales or none; cypsela wing-margined; outer involucral bracts ± herbaceous 
 (in part)

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 Show photos of:   Each photo represents one genus in this subgroup.