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1 Leaves linear, lanceolate, or oblancolate, > 4× as long as wide. |
2 Leaves phyllodial ( septate, hollow or flat, segmented); flowers white or purple; [plants of wetlands]. |
3 Umbels simple; leaves spatulate, broader towards the tip, often somewhat flattened in ×-section, rounded or obtuse at the apex |
3 Umbels compound; leaves tapering to a pointed tip, either flat or terete in ×-section. |
4 Leaves flat in ×-section, with obvious parallel venation and less obvious septae / cross-partitions |
4 Leaves terete in ×-section, the septae obvious. |
5 Plants 1-11 dm tall, annuals, sometimes mat-forming and adventitiously perennial; fruits 1-3 mm long, with lateral ribs; rays 3-15 |
5 Plants 6-24 dm tall, perennials from rhizomes or tubers; fruits 4-9 mm long, with lateral wings; rays 5-20 |
2 Leaves “normal” (non- septate, flat, continuous, and in some cases lobed, toothed, or spinose-margined); flowers blue, yellow, white, or whitish-green; [plants of wetlands or uplands]. |
6 Flowers borne in involucrate heads; corolla blue or greenish-white |
6 Flowers in compound umbels; corolla yellow or white. |
7 Stem leaves similar to the basal, all simple; corollas yellow; [ exotic, of disturbed areas] |
7 Stem leaves palmately 3-5-foliolate with linear leaflets, differing from the simple basal leaves; corollas white; [native, of blackland prairies and associated disturbed areas, from AL and TN westward] |
1 Leaves orbicular, ovate, or elliptic, < 4× as long as wide. |
8 Leaves orbicular, about as wide as, or wider than, long; base peltate or cordate. |
9 Leaves leathery, with spinose margins; inflorescence a head; flowers blue; [rare introduction] |
9 Leaves herbaceous or somewhat fleshy. toothed or lobed, but not spinose; inflorescence umbellate or verticillate; flowers white, greenish, or purplish; [collectively common and widespread]. |
10 Foliage and fruits (or ovaries) stellate- pubescent or glochidiate; leaves lobed, but otherwise entire; [rare exotic] |
10 Foliage and fruits (or ovaries) glabrous; leaves toothed, sometimes also lobed; [common natives and exotics] |
8 Leaves ovate or elliptic, 1.2-4× as wide as long; base cordate, peltate, or truncate. |
11 Leaves perfoliate; flowers yellow; [rare exotics]. |
12 Stem leaves entire; umbellets subtended by broad foliaceous bractlets |
12 Stem leaves serrate; umbellets lacking bractlets |
11 Leaves cordate or truncate at the base; flowers white, green, yellow, blue, or purple; |
13 Flowers greenish or blue; leaves all simple (sometimes stem leaves lobed); inflorescence a head or very congested (subcapitate) umbel; [plants of wetland situations, prostrate, creeping, or erect]. |
14 Inflorescence a very congested (subcapitate) umbel, with 4-9 flowers; leaves cordate at the base, long- petiolate, the petioles characteristically 2× as long as the leaf |
14 Inflorescence a head, with > 20 flowers; leaves cuneate to truncate at the base, sessile to short petiolate, the petioles < 1× as long as the leaf (except E. prostratum) |
13 Flowers yellow or purple; basal leaves simple, stem leaves usually compound; Inflorescence a compound umbel; [erect plants of upland situations]. |
15 Fruits (partly to fully mature) with thin- edged wings; flowers yellow or purple; central flower of each umbellet staminate and pedicelled; fruits all pedicelled in all umbellets |
15 Fruits ribbed (with rounded, cordlike ribs), lacking thin- edged wings; flowers yellow; central flower of each umbellet either staminate and pedicelled, or pistillate and sessile; fruits all pedicelled in some umbellets (those with a staminate central flower), or the central fruit sessile in some umbellets (those with a pistillate central flower) |
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2 Leaflets linear (resembling winged rachises); corolla white |
2 Leaflets broad, elliptic, ovate, or obovate, sparingly lobed; corolla yellow |
1 Leaflets variously serrate, dentate, and/or incised. |
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4 Corolla yellow, maroon, or pale creamy yellow. |
5 Flowers yellow, maroon, or pale creamy-yellow; central flower of each umbellet staminate and pedicelled; fruits all pedicelled in all umbellets; developing fruits subterete to slightly dorsally compressed, several or all of the ribs with thin- edged wings |
5 Flowers yellow; central flower of each umbellet either staminate and pedicelled, or pistillate and sessile; fruits all pedicelled in some umbellets (those with a staminate central flower), or the central fruit sessile in some umbellets (those with a pistillate central flower); developing fruits laterally compressed, all of the ribs rounded and cordlike |
4 Corolla white. {Add to keylead 4b: Apium graveolens var. dulce, Cicuta bolanderi, Cicuta mexicana, Imperatoria ostruthium, Petroselinum crispum} |
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7 Rays 16-25; leaves somewhat coriaceous; leaflet bases often cuneate or obliquely truncate; [plants of dry habitats] |
7 Rays 3-5; leaves thin in texture; leaflet bases rounded, subcordate, or broadly cuneate; [plants of moist forests] |
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8 Plants 1-9 dm tall at maturity; [rarely naturalized exotics]. |
9 Ovary (and later the fruits) terete, the ribs corky- winged; [plants of wetlands] |
9 Ovary (and later the fruits) laterally compressed, not winged; [plants of uplands] |
10 Umbellets (rays) 9-15 per umbel |
10 Umbellets (rays) (25-) 50-100 per umbel |
8 Plants 6-18 dm tall at maturity; [collectively common and widespread natives]. |
11 Sheaths of the upper leaves dilated, > 1 cm wide when flattened; [plants of moist habitats, from GA northward in the Mountains, extending into adjacent provinces towards the northern edge of our area] |
11 Sheaths of the upper leaves not dilated, < 1 cm wide; [plants either of wetlands or of moist to dry forests]. |
12 Veins of the leaflets directed to the sinuses; leaflets mostly 2.5-5× as long as wide, acuminate at the tip; [of wetlands] |
12 Veins of the leaflets directed to the tips of the teeth or lobes; leaflets mostly 1.3-1.8× as long as wide, acute to obtuse at the tip; [of moist to dry forests] |
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13 Fruit hispid or pubescent (regardless of winging). |
14 Fruits 4-6 mm long, hispid across the surfaces; rays 16-25; leaves somewhat coriaceous; leaflet bases often cuneate or obliquely truncate; [plants of dry habitats] |
14 Fruits 18-24 mm long, oblanceolate or linear, appressed- pubescent on the ribs; rays 3-5; leaves thin in texture; leaflet bases rounded, subcordate, or broadly cuneate; [plants of moist forests] |
13 Fruit glabrous (sometimes winged or prominently ribbed as well). |
15 Fruits dorsally compressed (strongly to slightly) or subterete, either thin- winged or corky- winged. |
16 Ribs very corky; fruits 2-3 mm long; [rare aquatic or semiaquatic exotic] |
16 Ribs thin- winged; fruits 3-8 mm long; [common natives of most to submesic forests]. |
17 Rays 12-30; fruits 4-8 mm long; plant 6-20 dm tall; sheaths of the upper leaves dilated, > 1 cm wide when flattened |
17 Rays 5-10; fruits 3-6 mm long; plant 5-10 dm tall; sheaths of the upper leaves not dilated, < 1 cm wide |
15 Fruits laterally compressed, not winged (except thin- winged in Ligusticum). |
18 Veins of the leaflets directed to the sinuses; leaflets mostly 2.5-5× as long as wide, acuminate at the tip; [of wetlands] |
18 Veins of the leaflets either directed to the tips of the teeth or lobes, or reticulating extensively and becoming obscure before reaching the margin; leaflets mostly 1.3-1.8× as long as wide, acute to obtuse at the tip; [of moist to dry forests]. |
19 Leaflet venation palmate- ternate, each leaflet with 3 (-5) main veins from the base (the central vein then with pinnate secondary veins); plants from rhizomes |
19 Leaflet venation pinnate, each leaflet with a dominant central vein (it then with pinnate secondary veins); plants from a caudex, taproot, or cluster of fibrous or fleshy roots. |
20 Lateral veins of the leaflet parallel and straight, clearly extending to the tip of each tooth; leaflet base often strongly oblique; leaflet margin entire in the lower ¼ to 1/3 |
20 Lateral veins of the leaflet arcing, reticulating and becoming obscure before reaching the leaflet margin; leaflet base symmetrical or slightly oblique; leaflet margin toothed to or very close to the base |
21 Umbellets (rays) per umbel (25-) 50-100 |
21 Umbellets (rays) per umbel 4-25 |