Flora of the Southeastern United States

1 Basal and lower stem leaves sessile (often cordate-clasping), or if petiolate then with cuneate to attenuate bases.

  2 Vegetative parts (stems, leaves, array branches, phyllaries) persistently bluish-glaucous; leaves slightly fleshy in texture and clasping; plants nearly glabrous (leaf margins scabrous, rarely upper stems somewhat hirsute); stems 2-7 (-12) dm tall; [subgenus Symphyotrichum, section Symphyotrichum, subsection Heterophylli, series Concinni].

  2 Vegetative parts (stems, leaves, array branches, phyllaries) green, not bluish-glaucous; leaves mostly not fleshy (except subg. Astropolium); plants glabrous or variously hairy; stems 2-30 dm tall.

    3 Leaves strongly basally disposed, basal leaves linear, upper cauline leaves much reduced; heads few, long-pedunculate (peduncles 1-20+ cm) in open ± corymbiform arrays; disc florets 47-57; [of wet pine savannas of FL and s. AL]; [subgenus Chapmaniani].

    3 Leaves cauline, basal and proximal leaves generally not linear, often withered by anthesis; heads few to many, mostly in paniculiform or racemiform arrays; disc florets often fewer; [collectively widespread].

      4 Ray florets mostly in 2-3 series, blades 1.3-4.2 mm, often not exceeding mature pappus (S. tenuifolium and S. bracei in 1 series to 8.5 mm); plants appearing entirely glabrous (leaf axils or margins sometimes inconspicuously strigillose); plants either taprooted annuals or perennials with succulent, linear, entire leaves; [coastal wetlands, often saline, or disturbed areas inland]; [subgenus Astropolium]

        5 Leaves succulent, linear (1-6 mm wide) and entire; ray laminae (4.5-) 5-8.5 (-9) mm, in a single series; plants perennial, heads (1-) 3-20 (-40).

        5 Leaves not succulent, usually broader or toothed; ray laminae 1.3-4.2 mm, usually in 2-3 series (laminae 3.7-7 mm and in 1 series in S. divaricatum); plants annual, often copiously branched, heads (10-) 30-100 (-150+).

      4 Ray florets in 1 series, mostly >4mm; stems usually pubescent at least in lines distally, leaves often pubescent or scabrous; plants perennials from crowns, caudices, or rhizomes, leaves not succulent; [various habitats, rarely saline].

          6 Stem leaves sessile, entire, and cordate- or auriculate-clasping at base (if only rounded or cuneate, then mostly 1-3 cm long); leaves crowded, internodes of main stem < 3.5 cm long (rarely longer in S. patens); plants stipitate-glandular in arrays (on upper stems, leaves, peduncles, bracts, and/or phyllaries; absent in sect. Concolores and sparse to absent in some vars. of S. patens); rays purple, blue, or lavender; [subgenus Virgulus]

          6 Stem leaves winged-petiolate (lower, often withering by anthesis) to sessile (upper), often toothed, bases attenuate to auriculate-clasping (main stem leaves mostly > 3 cm long); leaves not crowded, internodes of main stem > 3.5 cm long; arrays eglandular; rays white in some species.

             7 Phyllary tips widely spreading or recurved, usually either involute or foliaceous, faces glabrous or variously pubescent.

               8 Phyllary apices spinose, either tightly involute or tipped with a white spine; flowers white (except S. kentuckiense).

                 9 Free tips of phyllaries flat, tipped with a white spine (otherwise acute); stem leaves crowded (internodes mostly <1 cm), linear or oblong, 1-4 mm wide, usually upcurved; [subgenus Virgulus, section Ericoidei]

                 9 Free tips of phyllaries tightly involute, long-acuminate; stem leaves not crowded, often broader, not upcurved; [subgenus Symphyotrichum]

               8 Phyllary tips acute to acuminate, sometimes mucronate or apiculate (e.g., S. puniceum), flat (sometimes spreading at tips when foliaceous); flowers pink, purple, or lavender (rarely white in S. firmum).

                   10 Upper stems, peduncles, bracts, and phyllaries ±densely hirtellous and usually also stipitate-glandular; leaves entire, sessile, and mostly rounded to subclasping at base; [subgenus Virgulus]

                   10 Stems pubescent in lines distally (densely hirsute in S. puniceum), plants eglandular; leaves usually toothed, lower winged-petiolate, upper auriculate-clasping or cuneate; [subgenus Symphyotrichum]

             7 Phyllary tips appressed to ascending, faces glabrous (rarely sparsely strigillose).

                     11 Involucres turbinate, phyllaries in 6-9 series; ray laminae 12-20 mm long, pink to purple; peduncles (1-) 4-10 (-25) cm with numerous (8-15) appressed, linear-oblong bracts 1.5-4mm; stem leaves lacking axillary clusters; [subgenus Symphyotrichum, section Turbinellum]

                     11 Involucres campanulate to cylindric, phyllaries in 3-6 series; ray laminae 3-11 (-14) mm long (longer in S. boreale); peduncles not as above (except S. dumosum and S. estesii); stem leaves with or without axillary clusters

1 Head 1 per plant (individual rosette); stems 0.1-0.3 dm tall; [TX and OK westwards]

1 Heads 5-300+ per (well-developed) plant; stems 0.3-35 dm tall; [collectively widespread].

  2 Stems with numerous thorns (1-2 cm long, modified axillary branches), and few or no leaves

  2 Stems leafy, not armed with thorns.

    3 Leaves pinnatifid to bipinnatifid; plant annual

    3 Leaves unlobed; plant perennial from caudices, crowns, or rhizomes.

      4 Annuals from taproots; ray florets 0.3-7 mm long.

        5 Ray laminae 0.3-1.0 mm long; cypselas 1.0-1.5 mm long, compressed, 1-nerved on each face

        5 Ray laminae 1.3-7 mm long; cypselas (1.2-) 1.5-2.7 (-3) mm long, compressed or not, 5-18-nerved.

          6 Disc flowers 25-35 per head; ray flowers in 1 series

          6 Disc flowers 4-10 (-13) per head; ray flowers in 1-3 series

      4 Perennials from caudices, crowns, or rhizomes; ray florets > 3 mm long.

             7 Basal and lower stem leaves petiolate, with blades cordate to rounded at the base

               8 Heads borne in corymbiform arrays, the branches often subtended by large and leaf-like bracts; phyllaries < 2.5 (-3)× as long as wide, often > 1 mm wide; plants (in most species) colonial by rhizomes; rays (in most species) white; phyllaries (in many species) glandular

             7 Basal and lower stem leaves sessile (sometimes cordate-clasping), or if petiolate then with cuneate to attenuate bases.

                 9 Rays pink, purple, lavender, blue, or pale pink [plants with pale pink rays may need to be keyed both ways].

                   10 Heads borne in paniculiform or in diffuse and irregular arrays

                   10 Heads borne either in flat-topped or rounded, corymbose arrays, or in narrow racemiform or spiciform panicles, or solitary.

                     11 Leaves 1.2-4.0 cm long, 1-4 mm wide, stiff, scabrous margined and weakly spine-tipped; plants 1-7 dm tall; pappus in 2 series, the inner much longer than the outer (ca. 1 mm long) bristles

                     11 Leaves either longer or broader or both, herbaceous; Leaves (5-) 13-45 mm wide, herbaceous, neither scabrous-margined nor spine-tipped; plants 4-30 dm tall; pappus not divided into distinct inner and outer series.

                       12 Plants 10-35 dm tall; larger leaves (basal or low on the stem) with cuneate or attenuate bases, the blades 30-50 cm long; [non-native, rarely persistent or spreading from horticultural use]

                       12 Plants 1-12 dm tall; larger leaves with blades 2-20 cm long; [natives, collectively widespread and common in our region]

                 9 Rays white (or very slightly pink-flushed).

                          13 Heads borne in paniculiform or in diffuse and irregular arrays

                          13 Heads borne either in flat-topped or rounded, corymbose arrays, or in narrow racemiform/spiciform panicles, or solitary.

                            14 Heads arrayed in 1 (or more) cylindrical thyrses

                            14 Heads borne in either narrow racemiform/spiciform panicles, or in corymbose arrays.

                              15 Heads borne in narrow racemiform/spiciform panicles

                              15 Heads borne in corymbose arrays.

                                16 Disc flowers white

                                16 Disc flowers yellow (and often fading to pink or purplish).

                                  17 Rays 2-7, the ray ligules 2-11 mm long, often twisted or contorted; phyllaries whitish with a distinct green tip, the green area about as wide as long

                                  17 Rays (8-) 9-40, the ray ligules 4-20 mm long, generally planar (or neatly coiling at post-maturity); phyllaries various.

                                    18 Pappus double, with an outer set of bristles < 1 mm long; leaves entire

                                    18 Pappus not divided into distinctively different outer and inner series; leaves toothed or entire.

                                       19 Achenes not glandular, either glabrous or strigillose

                                       19 Achenes densely gland-dotted