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Key to Asteraceae, Key B: herbaceous composites with opposite or whorled leaves
and discoid or disciform heads (lacking ray florets)

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1 Pappus present, of 5-60 barbellate bristles; receptable naked (without paleae or well-developed bristles); [tribe Heliantheae; subtribe Eupatoriae].
..2 Plant a twining herb, phyllaries and disk florets 4 per head
..2 Plant stiffly erect to weakly spreading but never twining, phyllaries and disk florets usually > 4 per head.
....3 Leaves in whorls of 3-7, > 2 cm wide
....3 Leaves opposite, rarely alternate or whorled, if whorled, < 2 cm wide.
......4 Achenes (and ovaries) 8-10-ribbed; outer phyllaries longitudinally striate
......4 Achenes (and ovaries) (3-) 4-5-ribbed; outer phyllaries not noticeably longitudinally striate.
........5 Heads pink to blue.
..........6 Phyllaries in 4-6+ series, deciduous
..........6 Phyllaries in 2-4 series, persistent (or deciduous in Praxelis).
............ 7 Heads pink (rarely bluish); receptacles flat; florets 18-25 per head
............ 7 Heads blue; receptacles conic; florets 25-70 per head.
............ ..8 Bristles ca. 40; florets 25-30; phyllaries 15-25, unequal, deciduous (absence apparent in fruit)
............ ..8 Bristles ca. 30; florets 35-70+; phyllaries ca. 25, subequal, persistent
........5 Heads white to cream or, rarely, pale lilac.
............ ....9 Florets 3-7 per head
............ ....9 Florets at least 9 per head.
............ ......10 Phyllaries not strongly imbricate, with the principal ones subequal and sub-biseriate; petioles 0.5-10 cm
............ ......10 Phyllaries clearly imbricate, in 3+ series; some species epetiolate
1 Pappus absent, or of scales, setae, or awns; receptacle either naked, or with paleae or well-developed bristles.
............ ........11 Leaves whorled, linear, < 2 mm wide; head solitary; [aquatic herb growing in shallow stagnant water]
............ ........11 Leaves opposite (or alternate in part), broader in shape and > 5 mm wide; heads typically not solitary; [terrestrial or wetland plants].
............ ..........12 Receptacle naked.
............ ............ 13 Pappus of 4-10 scales; heads white, pink, or blue.
............ ............ ..14 Heads with 20-125 florets; leaves serrate; [rarely naturalized aliens in our area]
............ ............ ..14 Heads with 10-30 florets; leaves entire; [natives, of FL, s. GA, and MS in our area]
............ ............ 13 Pappus none, or of a few bristles or irregular coroniform lobes; heads green to yellow.
............ ............ ....15 Heads bright yellow, closely aggregated into corymbiform arrays of flat-topped to dome-shaped glomerules
............ ............ ....15 Heads greenish or greenish yellow, borne in spiciform, racemiform, or paniculiform arrays.
............ ............ ......16 Heads in paniculiform arrays, all or most of the heads not subtended by bracts
............ ............ ......16 Heads in spiciform or racemiform arrays, each 1 (-2) heads subtended by a bract
 Iva
............ ..........12 Receptable with paleae or well-developed bristles.
............ ............ ........17 Heads small, less than 1 cm in diameter at anthesis (the female heads enlarging in Xanthium); disc florets dull white or suffused with green or purple; florets mainly unisexual (either in the same heads and then males central and females peripheral, or in separate female and male heads); female florets 0-8 per head; [tribe Heliantheae; subtribe Ambrosiinae]
............ ............ ..........18 Heads unisexual; cypselas shed within an indurated bur or “nut” with hooked or straight spines developed from the phyllaries and/or paleae.
............ ............ ............ 19 Involucre of the female heads with tubercles or straight spines developing from the phyllaries; burs 1-8 mm long
............ ............ ............ 19 Involucre of the female heads with hooked spines developing from the phyllaries/paleae; burs 10-35 mm long
............ ............ ..........18 Heads bisexual, with functionally male and female flowers in the same head; cypselas shed individually, not enclosed.
............ ............ ............ ..20 Heads in paniculiform arrays, all or most of the heads not subtended by bracts
............ ............ ............ ..20 Heads in spiciform or racemiform arrays, each 1 (-2) heads subtended by a bract
 Iva
............ ............ ........17 Heads larger, mostly > 1 cm in diameter at anthesis; disc florets conspicuously white, yellow, pale yellow, or purple; florets mainly bisexual; female florets > 12 per head (except 2-8 in Polymnia).
............ ............ ............ ....21 Disc flowers maroon-purple; leaves mainly basal
............ ............ ............ ....21 Disc flowers white, pale yellow, or bright yellow; leaves mainly or strictly cauline.
............ ............ ............ ........23 Involucre of phyllaries not subtended by a calyculus
............ ............ ............ ........23 Involucre of phyllaries subtended by a calyculus of bracts obviously different in color, texture, and shape than the phyllaries
............ ............ ............ ......22 Disc flowers bright white or pale yellow.
............ ............ ............ ..........24 Disc flowers bright white; leaves unlobed or with 2 basal lobes
............ ............ ............ ..........24 Disc flowers creamy or pale yellow; leaves prominently pinnately lobed, with 5-many lobes

Key to Asteraceae, Key from FOV: for editing and augmentation:

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1 Receptacles with paleae or bristles.
..2 Pappus lacking or of scales or awns.
....3 Pappus lacking.
......4 Involucre of dentate or fimbriate phyllaries
......4 Involucre of the pistillate heads a bur with hooked prickles
....3 Pappus present.
........5 Phyllaries dentate or fimbriate
........5 Phyllaries entire
..2 Pappus of bristles.
..........6 Phyllaries fimbriate, dentate, or spiny; leaves often prickly or spiny
..........6 Phyllaries entire, leaves not prickly or spiny.
............ 7 Basal leaves 1-5 mm wide; outer florets pistillate
............ 7 Basal leaves > 5 mm wide (except in Liatris pseudoliatris); florets all perfect.
............ ..8 Phyllaries hooked at tip; heads forming burs at maturity
............ ..8 Phyllaries not hooked at tip; heads not forming burs at maturity.
............ ....9 Heads larger, the involucre 6-15 mm high, with 15-40 phyllaries; leaves with conspicuous (at least at 10× magnification) resin dots
............ ....9 Heads small, the involucre 3.5-6 mm high, with 5-12 phyllaries; leaves without shining punctate glands (except punctate-glandular in Litrisa, of the FL peninsula).
............ ......10 Stem with punctate glands; peduncles punctate-glandular and also hirsutulous; pappus bristles in 2 series; [of FL peninsula]
............ ......10 Stem eglandular, glabrous or spreading-hirsute; peduncles glabrous or stipitate-glandular; pappus bristles in 1 series; [widespread in the Coastal Plain]
1 Receptacles naked.
............ ........11 Pappus lacking or of scales or awns.
............ ..........12 Disk florets blue or purple.
............ ............ 13 Heads few-flowered, aggregated into secondary heads with leafy bracts
............ ............ 13 Heads many-flowered, not aggregated into secondary heads
............ ..........12 Disk florets yellow to yellowish green or reddish to reddish brown.
............ ............ ..14 Cypselas winged and spined; heads sessile in the branch forks
............ ............ ..14 Cypselas not winged and spined; heads not sessile in the branch forks.
............ ............ ....15 Inflorescence elongate, paniculiform, spiciform, or racemiform
............ ............ ....15 Inflorescence a flat-topped corymb, or heads solitary.
............ ............ ......16 Receptacle strongly convex and pointed; plants pineapple-scented
............ ............ ......16 Receptacle flat to convex; plants scented, but not of pineapple
............ ........11 Pappus of barbellate or plumose bristles.
............ ............ ..........18 Perennial; leaves remotely toothed to entire; [of shale barrens]
............ ............ ..........18 Annual; leaves irregularly toothed to pinnatifid; [weed of disturbed soil]
............ ............ ........17 Heads white, whitish, pink, purple, red,
............ ............ ............ ..20 Larger leaves hastate; heads whitish
............ ............ ............ ..20 Leaves not hastate; heads whitish to red or pink to violet or deep purple.
............ ............ ............ ....21 Phyllaries in essentially one series; leaves palmately veined, ovate to reniform
............ ............ ............ ....21 Phyllaries in several series; leaves variously veined, linear to broadly ovate.
............ ............ ............ ......22 Heads white or whitish; [of uplands]
............ ............ ............ ......22 Heads pink to red or violet to deep purple or, rarely, white; [of uplands or wetlands].
............ ............ ............ ........23 Pappus double with inner bristles long and the outer very short
............ ............ ............ 19 Some or all florets pistillate.
............ ............ ............ ............ 25 Phyllaries in essentially one series; fresh plants not strongly scented
............ ............ ............ ............ 25 Phyllaries in several series; fresh plants with a strong, aromatic fragrance
............ ............ ............ ..........24 Leaves white woolly or gray-tomentose, at least beneath (abaxially).
............ ............ ............ ............ ......28 Bristles barbellate to barbellulate; pappi falling
............ ............ ............ ............ ........29 Pappus bristles united at their base, falling as units.
............ ............ ............ ............ ..........30 Blooming Mar-Jul; phyllaries in 3-7 series, sometimes tinged with purple or brown but lacking a conspicuous dark brown spot
............ ............ ............ ............ ..........30 Blooming Jul-Oct; phyllaries in 2-3 series, some or all phyllaries bearing a conspicuous (distal-middle) dark brown spot
............ ............ ............ ............ ........29 Pappus bristles distinct, not united at the base and falling seperately.
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