No key was found for the requested taxon, but it has only one child: Schkuhria pinnata. Showing where it is keyed below.

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Key to Asteraceae, Key B: herbaceous composites with opposite or whorled leaves
and discoid or disciform heads (lacking ray florets)

Asteraceae

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1 Pappus present, of 5-60 barbellate bristles; receptacle naked (without paleae or well-developed bristles); [tribe Heliantheae; subtribe Eupatoriae].
  2 Plant a twining herb, phyllaries and disk florets 4 per head
  2 Plant stiffly erect to sprawling but never twining, phyllaries and disk florets usually > 4 per head.
    3 Leaves in whorls of 3-7, > 2 cm wide
    3 Leaves opposite, rarely alternate or whorled, if whorled, < 2 cm wide.
      4 Cypselae rostrate (with long beaks); the achene portion not bearing ribs
      4 Cypselae not beaked, the achene variously ribbed.
        5 Achenes (and ovaries) (3-) 4-5-ribbed; outer phyllaries not noticeably longitudinally striate.
          6 Heads pink to blue.
             7 Phyllaries in 2-4 series, persistent (or deciduous in Praxelis).
               8 Heads pink (rarely bluish); receptacles flat; florets 18-25 per head; leaves sometimes gland-dotted
               8 Heads blue; receptacles conic; florets 25-70 per head; leaves gland-dotted.
                 9 Bristles ca. 40; florets 25-30; phyllaries 15-25, unequal, deciduous (absence apparent in fruit)
          6 Heads white to cream or, rarely, pale lilac.
                     11 Phyllaries not strongly imbricate, with the principal ones subequal and sub-biseriate; petioles 0.5-10 cm
1 Pappus either absent, or of scales, setae, or awns; receptacle naked, paleate, or bearing bristles.
                       12 Leaves whorled, linear, < 2 mm wide; head solitary; [aquatic herb growing in shallow stagnant water]
                       12 Leaves opposite (or alternate in part), broader in shape and > 5 mm wide; heads typically not solitary; [terrestrial or wetland plants].
                            14 Pappus of 2-12 scales; heads white, pink, or blue (yellow in Schkuhria).
                              15 Heads with 20-125 florets; leaves serrate or ± dentate (at least distally); [rarely naturalized exotics or s. TX/FL natives]; [tribe Eupatorieae].
                                16 Leaves petiolate; corolla tube glabrous, typically blue or lavender colored (sometimes white tinged); heads with 20-125 florets; [naturalized exotics or s. FL native]
                                16 Leaves sessile; corolla tube glandular-pubescent, typically white colored (sometimes pink-purple tinged); heads with 75-125 florets; [s. TX native]
                              15 Heads with 10-30 florets (or fewer in Schkuhria); leaves entire; [natives, of FL, s. GA, MS, and TX in our area]; [tribe Heliantheae; subtribe Chaenactidinae].
                                  17 Leaves 3-5 lobed (or foliolate); cypselae with curled hairs (Florestina tripteris) or villous on angles (Schkuhria pinnata); [s. TX in our area or ne. waif].
                                    18 Heads discoid, sometimes with 1 (-2) diminuitive rays, corolla (of discs) yellow; cypselae villous, at least at bases or on angles; [waif of ne US, native in sw. US]
                                  17 Leaves simple or unlobed; cypselae with straight hairs; [variously distributed in s. GA and FL w. to MO and s. TX]
                            14 Pappus none, or of a few bristles or irregular coroniform lobes; heads green to yellow.
                                       19 Heads bright yellow, closely aggregated into corymbiform arrays of flat-topped to dome-shaped glomerules
                          13 Receptacles with paleae or well-developed bristles (the pales sometimes modified into specialized perigynia or burs surrounding the achene).
                                           21 Involucre of four decussate, deltoid bracts (the outer two large and longer than and often enclosing the flowering heads); pappus absent; paleae tightly enclosing the cypselae; plants rooting at the nodes, sometimes free-floating in water; [uncommon non-native, c. FL]
                                           21 Involucre not of four decussate, deltoid bracts; plants not with the above combination of characters; [widespread natives and non-natives]
                                             22 Heads small, less than 1 cm in diameter at anthesis (the female heads enlarging in Xanthium); disc florets dull white or suffused with green or purple; florets mainly unisexual (either in the same heads and then males central and females peripheral, or in separate female and male heads); female florets 0-8 per head; [tribe Heliantheae; subtribe Ambrosiinae].
                                               23 Heads unisexual; cypselas shed within an indurated bur or “nut” with hooked or straight spines developed from the phyllaries and/or paleae.
                                               23 Heads bisexual, with functionally male and female flowers in the same head; cypselas shed individually, not enclosed.
                                             22 Heads larger, mostly > 1 cm in diameter at anthesis; disc florets conspicuously white, yellow, pale yellow, or purple; florets mainly bisexual; female florets > 12 per head (except 2-8 in Polymnia and 8-15 in Verbesina occidentalis).
                                                      26 Leaves strongly basally disposed, the basal-most leaves sitting almost flat on the ground and overlapping; disc flowers maroon-purple
                                                      26 Leaves mainly or strictly cauline (not basally disposed); disc flowers white, yellow, or reddish-brown.
                                                          28 Involucre of phyllaries not subtended by a calyculus (phyllaries sometimes in 2+ series, but without obvious calyculi below).
                                                              30 Plants primarily prostrate or trailing, sometimes erect; heads with or without ray florets; [habitats various, widespread natives and non-natives]