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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) |
1 Leaflets narrowly lanceolate or linear, > 8× as long as wide, entire; umbels compound and regular, the rays and pedicels each of relatively uniform lengths; leaves 3-5-foliolate. |
..2 Fruit 2-3 mm long; leaves 1-5-foliolate; [of calcareous or rich moist to wet areas, AL and TN and westward] |
..2 Fruit 3-5 mm long; leaves 1-3-foliolate; [of saturated acid wetlands, of the FL Panhandle, e. GA, e. SC, e. NC, and e. VA] |
1 Leaflets ovate, obovate, broadly lanceolate, or broadly oblanceolate, 1-5× as long as wide, serrate or variously incised or cleft; umbels compound and irregular, the rays and/or pedicels of widely varying lengths; leaves 3-7-foliolate. |
....3 Rays 3-8, the involucre absent or inconspicuous; umbellets with 3-10 pedicellate perfect flowers; fruits linear-oblong, glabrous; leaves 3-foliolate, the lateral leaflets often 2-parted; corollas white |
....3 Rays few, the involucre of prominent, broad, foliaceous bracts; umbellets with 3 sessile to subsessile or short-pedicellate perfect flowers and a variable number of pedicellate staminate flowers; fruits ovoid, obovoid, or subglobose, covered with uncinate bristles; leaves palmately 3-7-foliolate, the lateral sometimes 2-parted; corollas greenish-white, yellowish-green, or white |