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1 Leaves pinnatifid to bipinnatifid, the primary sinuses extending 9/10 or more of the way to the midrib; leaves thin in texture; pappus of 2 petaloid scales; [section Parthenium]. |
..2 Annuals (rarely persisting); leaf blades (1-)2-pinnately lobed, scabrellous below and seldom accompanied with erect hairs 1-2 mm long |
..2 Biennials (sometimes flowering first year or persisting); leaf blades ± pinnately lobed, strigillose below and usually accompanied with erect hairs 1-2 mm long |
1 Leaves toothed (pinnatifid or sinuous-margined in forms of P. integrifolium var. mabryanum, the sinuses extending up to 3/4 of the way to the midrib); leaves somewhat thick in texture; pappus of 2-3 weak awns; [native perennials]; [section Partheniastrum]. |
....3 Plants arising from a short caudex surmounting a system of fleshy-thickened but tough roots; stems glabrous or with short, appressed pubescence < 1 mm long; cauline leaves seldom auriculate-clasping, the upper cauline leaves typically sessile or petiolate, the lower cauline leaves petiolate, the petioles winged or not; blades of basal leaves (4-) 6-21 (-27) cm long, (1.4-) 2-12 (-13.5) cm wide. |
......4 Blades of basal leaves ovate-lanceolate, (4-) 6-12 (-20) cm long, (3-) 4-8 (-9.5) cm wide, coarsely toothed but never undulately lobed; heads mostly 5-7 mm across, usually (18-) 90-180 (-400) per inflorescence; [widespread in our area] |
......4 Blades of basal leaves linear-lanceolate to ovate-lanceolate, (6-) 7-12 (-13.5) cm long, (1.4-) 2-4 (-4.5 cm) wide, coarsely toothed and sometimes also undulately lobed throughout their length; heads mostly 4-6 mm across, usually (30) 40-75 (-85) per inflorescence; [of Coastal Plain and eastern Piedmont of VA, NC, and SC] |
....3 Plants arising from a long, even-width, 3-5(-6) mm wide, branching, woody or lignescent rhizome; stems either with coarse, spreading pubescence 1-3 mm long or puberulous or strigose with hairs < 1 mm long; cauline leaves all auriculate-clasping, the upper cauline leaves sessile and auriculate-clasping, the lower cauline leaves with winged petioles, the wings expanded at the base; blades of basal leaves 11-18 (-20) cm long, 5-8 cm wide. |
........5 Leaves stiffly to loosely, sparsely to densely villous on both sides with thin, white hairs arising from a slender, non-pedestaled base; stems hirsute-pilose with white hairs 1-3 mm long; heads 4-7 mm in diameter |
........5 Leaves hispid with short, basally erect hairs, each arising from a “pedestal” of 2-4 concentric rings of glassy cells; stems either sparsely to densely hirsute-villous with white hairs 1-2 mm long, or merely puberulous or strigose with minute, appressed hairs 0.1-0.8 mm long; heads 7-10 mm in diameter |
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 |