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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 |
............ ..........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 |
............ ............ ........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. |
............ ............ ............ ......22 Disc flowers bright yellow. |
............ ............ ............ ........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 |
1 Receptacles with paleae or bristles. |
..2 Pappus lacking or of scales or awns. |
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......4 Involucre of dentate or fimbriate phyllaries |
......4 Involucre of the pistillate heads a bur with hooked prickles |
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........5 Phyllaries dentate or fimbriate |
........5 Phyllaries entire |
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..........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] |
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............ ........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. |
............ ............ ........17 Heads yellow. |
............ ............ ..........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, |
............ ............ ............ 19 Florets all perfect. |
............ ............ ............ ..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 bristles of one length |
............ ............ ............ ........23 Pappus double with inner bristles long and the outer very short |
............ ............ ............ 19 Some or all florets pistillate. |
............ ............ ............ ..........24 Leaves not white-woolly. |
............ ............ ............ ............ 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). |
............ ............ ............ ............ ..26 Plants dioecious. |
............ ............ ............ ............ ....27 Blooming Jul-Sep; leaves numerous on stem |
............ ............ ............ ............ ....27 Blooming Mar-May; leaves basally disposed |
............ ............ ............ ............ ..26 Plants not dioecious. |
............ ............ ............ ............ ......28 Bristles plumose; pappi persistent |
............ ............ ............ ............ ......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. |
............ ............ ............ ............ ............ 31 Involucre < 4 mm; mature plants > 25 cm tall |
............ ............ ............ ............ ............ 31 Involucre 4-8 mm; mature plants usually > 2 dm tall |