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Click the number at the start of a key lead to highlight both that lead and its corresponding lead. Click again to show only the two highlighted leads. Click a third time to return to the full key with the selected leads still highlighted.

Key to Asteraceae, Key H: Herbaceous composites with the leaves alternate, the heads lacking rays, and with a pappus of bristles only

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1 Receptacle paleate (bearing receptacular bracts which individually subtend at least some of the flowers of the head).
  2 Involucres absent or vestigial, usually with 0 phyllaries; heads very small, < 6 mm high, < 4 mm wide; annuals, < 4 dm tall; disc corollas hidden or dingy in color; [tribe Gnaphalieae].
    3 Receptacles cylindric to clavate (5-15× as tall as the diameter); most paleae of pistillate flowers open to ± folded (at most each enfolding, not enclosing a floret; apices acuminate to aristate); innermost paleae erect to ascending in fruit; cypselae monomorphic (the outer ± equaling the inner)
    3 Receptacles obovoid (0.4-1.6× as tall as the diameter); most paleae of pistillate flowers ± saccate, each ± enclosing a floret, apices blunt; innermost paleae spreading in fruit; cypselae dimorphic (the outer longer than the inner)
  2 Involucres present, conspicuous, of many phyllaries; heads larger, 2-20+ mm wide; perennials or coarse annuals, 2-25 dm tall; disc corollas apparent, white, or pink to purplish or reddish.
      4 Phyllaries tipped by a hooked spine
        5 Cypselae with 5 angles or 5 grooves; involucre 2-3 mm tall and in diameter; pappus of 1 (-5+) usually glandular setae (interpretable as bristles, hence keyed here); [Coastal Plain; FL and GA]
        5 Cypselae with 10 ribs; involucre 3.5-12 (-15) mm tall and in diameter; pappus of 35-40 barbellulate bristles; [mainly Coastal Plain; VA south to s. FL, west to e. LA]
          6 Heads larger, the involucre 6-15 mm high, with 15-40 phyllaries; leaves with conspicuous (at least at 10× magnification) resin dots.
          6 Heads smaller, the involucre 3.5-6 mm high, with 5-12 phyllaries; leaves without shining punctate glands (except punctate-glandular in Litrisa carnosa, of the FL peninsula).
             7 Stem with punctate glands; peduncles punctate-glandular and also hirsutulous; pappus bristles in 2 series; [of FL peninsula]
             7 Stem eglandular, glabrous or spreading-hirsute; peduncles glabrous or stipitate-glandular; pappus bristles in 1 series; [widespread in the Coastal Plain].
1 Receptacle epaleate (lacking receptacular bracts individually subtending flowers, but the receptacle sometimes bearing bristles, setae, hairs, or pits with laciniate margins; some taxa lacking paleae on many or most flowers of the head are keyed here as well, as a failsafe).
               8 Phyllaries in 1-2 series and equal or subequal in length to one another, the phyllaries often coherent/fused (the involucre thus appearing as a cylinder with ribs extending from base to top, except in species in which the phyllaries are radially winged); calyculus (of bracts subtending the phyllaries and differing from them in texture, color, or orientation) present or not; [tribe Senecioneae]
                 9 Annuals, 2-10 dm tall (or perennial, vining or sprawling and to 30 dm long in Gynura); leaves cauline and alternate; disc flowers orangey-brown, brick-red, purplish, yellow.
                   10 Plants perennial, vining or sprawling, velutinous or villous with purple hairs
                   10 Plants annual, upright or ascending, not purple-hairy.
                 9 Perennials (robust annuals in Erechtites), 2-30 dm tall; leaves basally disposed and alternate on the stem (except only alternate in Erechtites); disc flowers cream or yellow (rarely pale lavender in Arnoglossum).
                       12 Plants annual, with leaves primarily on the stem; leaves sharply and raggedly toothed or even pinnately lobed; heads disciform (the outer flowers female, the middle bisexual, and the inner functionally male)
                       12 Plants perennial, with leaves basally disposed (larger basal leaves, decreasing in size upwards, the basal leaves sometimes withering late in the year); leaves with generally regular toothing, stem leaves sometimes pinnately lobed; heads discoid (all flowers bisexual)
                            14 Perennials; leaves basally disposed, the basal or lower stem leaves unlobed (though toothed)
                            14 Annuals; leaves not basally disposed, evenly distributed on the stem, the lower stem leaves more-or-less pinnatifid
                          13 Disc flowers cream, white, or greenish white (to pale lavender in some Arnoglossum).
                              15 Phyllaries 7-21, not radially winged; disc flowers 10-55 (-80+); calyculus absent or of 1-9+ bracts.
                                16 Plants (5-) 6-24 dm tall; calyculus of 4-9+ bracts; [collectively relatively widespread in our region]
                                16 Plants 1-7 dm tall; calyculus absent or of 1-5+ bracts; [Mountains of w. NC and e. TN]
               8 Phyllaries in 3-17 series and unequal in length (imbricated); calyculus absent.
                                  17 Stem not winged (sometimes the leaves decurrent < 2 cm down the stem from the node).
                                       19 Plants perennial, mat-forming by stolons, with basal rosettes of spatulate leaves, these usually with obvious appressed hairiness on (at least) the lower and (sometimes also) the upper blade surfaces; erect stems (with scattered alternate leaves) 4-45 cm tall; plants usually dioecious (pistillate and staminate heads on separate plants)
                                       19 Plants annual, biennial, or perennial, not mat-forming or stoloniferous, erect, the leaves usually lanceolate or linear (spatulate in some species), leaf surface hairiness variable; erect stems (with alternate leaves) 5-80 cm tall; plants hermaphroditic (with heads containing both pistillate and functionally staminate flowers) or dioecious or subdioecious (in Anaphalis).
                                         20 Plants annuals (perennials in Omalotheca sylvatica); heads disciform (each bisexual); plants hermaphroditic.
                                           21 Leaves various in shape, the lager > 4 mm wide, acuminate, acute, obtuse or rounded at the tip; pappus readily falling, the bristles barbellate to barbellulate.
                                             22 Heads in capitate clusters arrayed in corymbiform or paniculiform arrays; phyllaries white or silvery; pappus bristles distinct, falling individually
                                             22 Heads in spicate arrays, or in glomerules axillary to leaves or well-developed bracts; phyllaries white to red-tinged or brown; pappus connate at the base into a ring, falling as a unit.
                                                 24 Annual; phyllaries in 3-7 series; cypselas papillate or glabrous; involucre white to red-tinged or brown; [widespread in our region]
                                                              30 Plants dioecious, either male or female; heads either staminate, with 10-50 flowers, or pistillate, with 20-150 flowers; heads pale yellow to white
                                                              30 Plants hermaphroditic; heads bisexual, with 2-35 flowers, either all perfect (bisexual), or a mixture of perfect (bisexual) and functionally staminate flowers.; heads yellow to pale yellow.
                                                                   32 Larger leaves 2.5-10 cm long, 1-4 cm wide; involucres 6-12 mm in diameter; [widespread in our region]
                                                                   32 Larger leaves 1-5 cm long, < 1 cm wide; involucres 2-7 mm in diameter; [s. and se. TX].
                                                                       34 Phyllaries either spine-tipped, or appendaged with a marginal zone that is strikingly different in color and texture than the phyllary body (except Leuzea); receptacle epaleate, but densely beset with bristles or subulate scales (flattened bristles).
                                                                                38 Flower heads pink, lavender, or purplish; phyllary appendages scarious and spineless, decurrent along the phyllary margin nearly to the phyllary base; perennial; flowers pink to purple, flowering Jun-Oct
                                                                                38 Flowers heads blue; phyllary appendages not or only slightly decurrent along the phyllary margins; annual; flowers pale to medium blue, flowering Apr-Jun
                                                                                        42 Pappus bristles in 1 series; heads disciform (the outer flowers of the head pistillate, the inner flowers of the head functionally staminate); leaf margins toothed; corollas white to cream or pink (rarely purple)
                                                                                        42 Pappus bristles in 2 series, the outer much shorter; heads discoid (all flowers bisexual and fertile); leaf margins toothed or entire; corollas purple or deep pink (rarely pale pink or white)
                                                                                                          50 Heads borne in corymbiform arrays; involucres 6-12 (15) mm tall; receptacles paleate, at least towards the periphery of the receptacle; pappus of 35-40 barbellulate to barbellate bristles; [nearly restricted to the Coastal Plain]
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