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1 Rays primarily pink or purple, not white-tinged (flowers viewed from above, adaxial surface of the rays). |
..2 Receptacles epaleate; leaves pinnatisect; [waif, ne. US] |
..2 Receptacles paleate; leaves simple or bladeless; [widespread natives] |
....3 Leaves without blades (the petioles terete, appearing Juncus-like); ray florets pink or purplish; disc florets fewer (60-120+), the corollas usually yellowish; [wet pinelands and seepages] |
....3 Leaves broad and conspicuous; ray florets purple; disc florets many (200+), the corollas pink, green, red, purple, or yellow colored; [plants of prairies and similar habitats] |
1 Rays primarily white to white-tinged or yellow throughout (lamina of the ray with at least some white basally if not uniformly yellow). |
......4 Disc florets functionally staminate (thus cypselae only forming from ray florets) |
......4 Disc florets bisexual, fertile. |
........5 Leaves entire or toothed, but not deeply pinnatisect; sometimes with smaller rounded lobes ( Leucanthemum basal leaves can have deeper, round lobes); plants usually not aromatic. |
..........6 Stem internodes usually winged (at least proximally) |
..........6 Stems not winged. |
............ 7 Leaves primarily basal, the cauline leaves absent or fewer and much reduced in size from basal leaves; abaxial surface of the ray laminae white or sometimes pink-tinged (on live plants) but lacking a prominent colored midstripe. |
............ ..8 Leaves strigose, the margins crenate-serrate; roots not red-tipped; abaxial surface of ray laminae often pink or purple tinged, flowers closing at night |
............ ..8 Leaves glabrous (or faces sparsely hairy), the margins entire or toothed; roots usually red-tipped; rays drying pinkish but abaxial surface not conspicuously pink tinged on live plants |
............ 7 Plants with well-developed cauline leaves, the margins entire or sometimes toothed (usually entire in Aphanostephus, occasionally deeply lobed); abaxial surface of the ray lamina sometimes white, but often with a prominent purple or blue midstripe (except Leucanthemum, which merely dries pink) |
............ ....9 Flowering heads smaller, arranged in corymbiform or paniculiform arrays; ray florets with diminuitive laminae (0.3-5.0 mm long), heads thus sometimes superficially appearing disciform (rays sometimes double in horticultural forms as in Achillea ptarmica) |
............ ......10 Plants aromatic; leaves linear to narrowly lanceolate, the surfaces glabrous or sparsely hairy; pales more or less folded but lacking distal papillae; cypselae not shed along with subtending phyllary and disc florets; [tribe Anthemideae] |
............ ......10 Plants not aromatic; leaves variously shaped, at least some usually lyrate or oblanceolate (not all linear), the surfaces hairy and gland-dotted (at least abaxially); pales distally pappilate or fimbriate; cypselae shed along with subtending phyllary and 2 disc florets each invested in a pale; [tribe Heliantheae] |
............ ....9 Flowering heads larger, singular on scapes (if in 2's or 3's, these large and not in broad corymbiform arrays), rays prominent, the laminae usually > 10 mm long |
............ ........11 Rays white abaxially (drying pinkish); receptacles broadly convex, not pitted; plants rhizomatous perennials; pappus absent; [tribe Anthemideae] |
............ ........11 Rays white or with prominent blue or purple midstripe (sometimes present after drying); receptacles conic, pitted; plants tap-rooted annuals (except Astranthium riddellii); pappus absent, coroniform, or of scales; [tribe Astereae] |
............ ..........12 Phyllaries scarious margined; cypselae 4-angled and with 4-12 thick ribs, pappus absent, of scales or coroniform; ray florets closing distally at night |
............ ..........12 Phyllaries sometimes hyaline but not scarious margined; cypselae compressed, lacking prominent ribs (though sometimes glochidiate), pappus absent or short coroniform; ray florets not closing at night |
........5 Leaves deeply lobed or pinnatisect, the ultimate segments linear or if rounded, the sinuses of the lobes nearly reaching the midrib (pinnatifid); plants typically aromatic (except Tripleurospermum and Parthenium); [tribe Anthemideae]. |
............ ............ 13 Receptacles paleate (chaffy or with apparent bracts), the pales sometimes distally fimbriate or papillate ( Parthenium). |
............ ............ ..14 Stem internodes usually winged |
............ ............ ..14 Stems not winged. |
............ ............ ....15 Rays (the laminae) white with conspicuous yellow coloration at the bases |
............ ............ ....15 Rays primarily white to white-tinged (without strong yellow color at the base of the laminae) or yellow throughout (lamina of the ray with at least some white basally; if rays are white). |
............ ............ ......16 Flowering heads smaller, arranged in corymbiform or paniculiform arrays; ray florets with diminuitive laminae (0.3-5.0 mm long); ray and disc florets both white or white-ish. |
............ ............ ........17 Plants usually aromatic; pales more or less folded but not distally fimbriate or papillate; cypselae not shed along with phyllary and disc florets; [tribe Anthemideae] |
............ ............ ........17 Plants not aromatic (at least not conspicuously so); pales distally fimbriate or papillate; cypselae shed along with subtending phyllary and 2 disc florets each invested in a pale; [tribe Heliantheae] |
............ ............ ......16 Flowering heads larger, arranged mostly singular at the ends of scapes, not in broad corymbiform arrays (except Tripleurospermum, which has larger heads and prominent rays), ray laminae prominent; ray and disc florets differing in color (rays typically white; discs typically yellow). |
............ ............ ..........18 Plants annual, erect or decumbent, ill-scented or not; ultimate leaf margins dentate to lobed; cypsela ribs usually 9-10 (sometimes lacking); [widespread non-natives] |
............ ............ ..........18 Plants perennial and prostrate (mat-forming), aromatic; ultimate leaf margins entire; cypsela ribs weak; [waif, ne. US] |
............ ............ 13 Receptacles epaleate (lacking chaff). |
............ ............ ............ 19 Ultimate leaf lobes broad, ovate-shaped (not linear) |
............ ............ ............ 19 Ultimate leaf lobes linear. |
............ ............ ............ ..20 Plants usually aromatic; maturing flowering heads with deflexed ray laminae; cypsela 5-ribbed, lacking apical resin sacs |
............ ............ ............ ..20 Plants not aromatic; ray laminae not deflexed; cypsela with 3 ribs and 1-5 abaxial-apical resin sacs |
1 Receptacles chaffy (paleate). |
..2 Phyllaries dry, scarious-margined. |
....3 Ray florets 1-5 mm long; heads small in corymbiform arrays |
....3 Ray florets > 5 mm long; heads large, terminating the branches |
..2 Phyllaries herbaceous, not scarious on margins. |
......4 Ray florets < 2.5 mm long; disk florets sterile, with an undivided style |
......4 Ray florets > 5 mm long; disk florets fertile, with a divided style. |
........5 Ray florets pink or light purple, > 15 mm long; heads single |
........5 Ray florets white, 5-10 mm long; heads 20-100 in a compound corymb |
1 Receptacles naked (epaleate). |
..........6 Pappus absent or coroniform. |
............ 7 Achene faces minutely glandular-glochidiate (bearing small gland-like bristles) |
............ 7 Achene faces glabrous or short-strigose but not glandular-glochidiate. |
............ ..8 Leaves basal; cypselae marginally 2-ribbed; mature plants < 2 dm tall |
............ ..8 Leaves cauline (and sometimes also basal); cypselae with ± 10 ribs; mature plants > 2 dm tall |
............ ....9 Heads solitary or 2-3 in corymbiform arrays |
............ ....9 Heads 5-60+ in corymbiform arrays |
..........6 Pappus present, of bristles or scales. |
............ ......10 Heads primarily discoid with reduced ray florets |
............ ......10 Heads radiate with conspicuous ray florets. |
............ ........11 Taprooted annuals; ray florets 1-7 mm long. |
............ ..........12 Leaves and stems not fleshy, rarely glabrous; cypselas < 1.4 mm long |
............ ..........12 Leaves and stems fleshy, mostly glabrous; cypselas > 1.4 mm long |
............ ........11 Not taprooted and mostly perennials; ray florets > 3 mm long. |
............ ............ 13 Ray florets usually > 60; blooming Apr-Oct |
............ ............ 13 Ray florets usually < 60; blooming late May-Nov. |
............ ............ ..14 Receptacles hemispheric to conic; pappus often with 2-4 awns ( Boltonia) or lacking awns and coroniform ( Astranthium). |
............ ............ ....15 Achenes not narrowly winged, the surfaces minutely glandular-glochidiate (bearing small gland-like bristles) |
............ ............ ....15 Achenes narrowly winged, the surfaces sometimes puberulent but not glandular-glochidiate |
............ ............ ..14 Receptacles flat to slightly convex; pappus lacking awns. |
............ ............ ......16 At least the basal and lower leaves both petiolate and cordate/subcordate at base. |
............ ............ ........17 Often colonial; inflorescence corymbiform, flat-topped or rounded; outer phyllaries > 1 mm broad |
............ ............ ........17 Not colonial; inflorescence paniculiform, often elongate; outer phyllaries < 1 mm broad |
............ ............ ......16 Basal and lower leaves not both petiolate and cordate/subcordate at base. |
............ ............ ..........18 Leaves sessile and auriculate or cordate-clasping |
............ ............ ..........18 Leaves petiolate or epetiolate but not auriculate or cordate-clasping. |
............ ............ ............ 19 Cypselas glandular; pappus double |
............ ............ ............ 19 Cypselas not glandular; pappus single or double or in four series. |
............ ............ ............ ..20 Leaves silvery-silky on both sides (at least when young), entire |
............ ............ ............ ..20 Leaves not silvery-silky, entire or toothed. |
............ ............ ............ ....21 Pappus double, with inner bristles distinctly longer than outer bristles. |
............ ............ ............ ......22 Leaves not rigid, veiny, lanceolate to elliptic or ovate, > 6 mm wide |
............ ............ ............ ......22 Leaves rigid, 1-nerved, linear to linear-spatulate, < 5 mm wide |
............ ............ ............ ....21 Pappus simple with all bristles often about the same length. |
............ ............ ............ ........23 Ray florets white, few (usually 3-8); cypselas densely silky |
............ ............ ............ ........23 Ray florets white to pink or blue or purple, more numerous (usually 8-30); cypselas glabrous to pubescent but not densely silky. |
............ ............ ............ ..........24 Ray florets white; involucres < 6 mm long; phyllaries < 1 mm wide |
............ ............ ............ ..........24 Ray florets white or pink to blue or purple; involucres 7-12 mm long; phyllaries usually > 1 mm wide. |
............ ............ ............ ............ 25 Phyllaries glandular |
............ ............ ............ ............ 25 Phyllaries not glandular. |
............ ............ ............ ............ ..26 Phyllaries long-attenuate or loose and spreading |
............ ............ ............ ............ ..26 Phyllaries appressed, not long-attenuate. |
............ ............ ............ ............ ....27 Plants coarse-hairy; lowest leaves > 5 cm wide |
............ ............ ............ ............ ....27 Plants glabrous to hairy; lowest leaves < 3 cm wide |