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Solidago
See list of 25 species in this genusPubescence of the cypsela body can often be assessed by examining the ovary while plants are in flower. Given that the color of ray flowers sometimes fades on herbarium specimens with age, some collections of Solidago can be difficult to distinguish from small-headed Symphyotrichum. This confusion can be solved by noting the fresh ray flower color on herbarium labels. Hybridization is reported between closely related species but does not appear to be a common event on the New England landscape. References: Semple et al. (1999), Semple and Cook (2006).
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1a. Capitulescence nodding at the summit and/or with branches that have secund capitula [Fig. 452]
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2a. Leaves basally disposed (i.e., leaves progressively reduced upward, those of the apical portion of the stem smaller, often of different shape, and less petiolate than those of the basal portion) [Fig. 455]; plants usually with basal tufts of leaves
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3a. Stems and often the leaves closely and minutely pubescent [Fig. 456]; rays pale yellow
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3b. Stems and leaves glabrous or with long, scattered hairs or scabrous; rays bright yellow
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4a. Leaf blades fleshy, entire; capitula with 7–17 ray flowers; plants of Atlantic coast shorelines and saline marshes (inland along heavily salted roadways)
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4b. Leaf blades not fleshy, serrate to subentire; capitula with 1–12 ray flowers; plants not of Atlantic coast shores
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5a. Leaf blades adaxially strongly scabrous; stems prominently angled, each angle often with a narrow wing
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5b. Leaf blades glabrous, pubescent, or slightly scabrous adaxially; stems terete or striate, but without prominent angles
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6a. Lower leaf blades abruptly contracted to a petiole
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7a. Abaxial surface of leaf blades hirsute; capitulum with 4–7 disk flowers; cypsela body minutely pubescent (in part)
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7b. Abaxial surface of leaf blades glabrous; capitulum with 8–20 disk flowers; cypsela body glabrous
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6b. Lower leaf blades gradually tapered to the base
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8a. Lower leaves conspicuously sheathing, the petiole covering 50–75% of the circumference of the stem; capitulescence taller than wide; capitula with 1–8 ray flowers and 4–8 disk flowers; plants primarily of organic soil wetlands (in part)
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8b. Lower leaves not conspicuously sheathing, the petiole covering less than 50% of the circumference of the stem; capitulescence as wide as or wider than tall; capitula with 7–12 ray flowers and 9–14 disk flowers; plants of open or lightly shaded, mineral soils
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2b. Leaves chiefly cauline (i.e., leaves of the apical portion of the stem of nearly similar shape and not dramatically reduced in size relative to the leaves of the basal portion of the stem) [Fig. 454]; plants lacking tufts of basal leaves
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9a. Leaf blades triple-veined (i.e., with 3 conspicuous, parallel veins—a midrib and 2 evident and prolonged, lateral veins) [Fig. 453]
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10a. Stem glabrous and glaucous below the capitulescence; involucral bracts obtuse to acute at the apex, green
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10b. Stem pubescent in at least the apical half, not glaucous; involucral bracts acuminate at the apex, yellow-green
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11a. Leaf blades abaxially subglabrous or pubescent only on the midrib and major veins (also pubescent between the veins in var. hargeri), usually sharply serrate and relatively thin; involucre 2–3 mm tall; disk corollas 2.3–2.7 mm long
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11b. Leaf blades abaxially pubescent on and between major veins, usually subentire to remotely serrate and relatively firm; involucre (2.7–) 3–4 (–5) mm tall; disk corollas 3–3.4 mm long
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9b. Leaf blades pinnately veined (i.e., with much-branched lateral veins that are not aligned parallel to the midrib) [Fig. 457]
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12a. Leaf blades translucent-punctate, all entire, usually anise-scented when bruised
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12b. Leaf blades not translucent-punctate, some with teeth, not fragrant when bruised
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13a. Plants from a caudex, without creeping rhizomes; lower leaf blades abruptly tapered to a petiole; capitula with 3–6 ray flowers (in part)
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13b. Plants with long, creeping rhizomes; leaf blades sessile or nearly so; capitula with 6–11 (–12) ray flowers
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14a. Leaf blades abaxially pubescent, the hairs commonly found on the tertiary veins (as well as the midvein and primary lateral veins); stems conspicuously spreading-pubescent (varying to sparsely pubescent in ssp. aspera); widespread plants found throughout most of New England
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14b. Leaf blades ± glabrous abaxially, hairs, when present, few in number and confined to the midrib and primary lateral veins; stems glabrous or with pubescent lines of decurrence from the leaf blades; plants mainly of southern New England and the coastal plain
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15a. Involucre 2.5–4 mm tall; involucral bracts narrow-lanceolate to narrow-oblong, mostly 0.3–0.6 mm wide, acute at the apex; disk corollas 2.5–3.5 mm long
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15b. Involucre 4–6 mm tall; involucral bracts oblong to narrow-ovate, the larger 0.7–1.2 mm wide, obtuse to rounded at the apex; disk corollas 4–5.5 mm long
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1b. Capitulescence neither nodding at the summit nor with secund capitula [Fig. 458], either terminal and resembling a thryse or panicle or consisting of clusters of capitula in the axils of well-developed leaves
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16a. Leaves chiefly cauline (i.e., leaves of the apical portion of the stem of nearly similar shape and not dramatically reduced in size relative to the leaves of the basal portion of the stem) [Fig. 454]; plants lacking tufts of basal leaves
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17a. Capitula with 30–50 flowers, the ray flowers numbering 10–13; leaves of the stem below the capitulescence numbering 2–4 (–7); plants 5–35 cm tall, of alpine summits and plateaus (in part)
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17b. Capitula with 6–13 flowers, the ray flowers numbering (1–) 3–5; leaves of the stem below the capitulescence numbering 7–60; plants 30–150 cm tall, primarily of temperate forests, woodlands, edges, and fields
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18a. Leaf blades entire to obscurely toothed; cypsela body glabrous; capitulescence terminal, only the lower branches subtended by leaves [Fig. 458] (in part)
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18b. At least the lower leaf blades with prominent teeth; cypsela body pubescent; capitulescence partly or entirely axillary, only the upper portion (if any) not subtended by leaves
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19a. Leaf blades elliptic to ovate, 3–10 cm wide, 1.2–2.2 (–2.5) times as long as wide; stem angled, not glaucous
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19b. Leaf blades lanceolate to narrow-elliptic, 1–3 cm wide, 3–10 times as long as wide; stem terete, glaucous
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16b. Leaves basally disposed (i.e., leaves progressively reduced upward, those of the apical portion of the stem smaller, often of different shape, and less petiolate than those of the basal portion) [Fig. 455]; plants usually with basal tufts of leaves
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20a. Involucre 8–11 mm tall, composed of acuminate- to attenuate-tipped involucral bracts; cypsela body 4–5 mm long; lower leaf blades with an acuminate apex
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20b. Involucre 3–9 mm tall, composed of round- to acuminate-tipped involucral bracts; cypsela body shorter than 4 mm long; lower leaf blades usually with an obtuse to acute apex
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21a. Stem and often the leaves pubescent with minute, viscidulous hairs [Fig. 456]; involucral bracts narrow, acuminate at the apex, up to 0.5 (–0.75) mm wide at the midpoint
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21b. Stem and leaves glabrous or pilose, but not copiously pubescent with minute hairs; involucral bracts wider, rounded to acute at the apex, (0.75–) 1–2 mm wide at the midpoint
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22a. Leaves conspicuously sheathing, the petioles covering 50–75% of the circumference of the stem; plants primarily of organic soil wetlands (in part)
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22b. Leaves not conspicuously sheathing, the petiole covering less than 50% of the circumference of the stem; plants not of organic soil wetlands
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23a. Involucral bracts, especially the outer, with squarrose tips [Fig. 459]; involucre 5–9 mm tall
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23b. Involucral bracts appressed to ascending; involucre 3–6 mm tall (up to 9 mm tall in S. leiocarpa)
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24a. Leaf blades pilose on one or both surfaces; stems often pilose
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25a. Ray flowers white or yellow-white; involucre 3–5 mm long; involucral bracts white-brown or light yellow-brown to light green or white-green at the base, green at the apex, the colors often sharply contrasting
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25b. Rays yellow; involucre 4–6 mm long; involucral bracts light green or yellow-green at the base, green at the apex, the colors usually weakly contrasting
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24b. Leaf blades glabrous or nearly so (sometimes scabrous); stems essentially glabrous (though often pubescent in the capitulescence)
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26a. Cypsela body glabrous; capitula with 5–9 ray flowers; plants of temperate woodlands, edges, and fields
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27a. Capitulescence panicle-like, usually with several ascending branches [Fig. 458]; leaf blades entire or sometimes the lower ones slightly toothed, the middle blades (1.5–) 2–7 cm wide; cypsela body 1.1–2 mm long (in part)
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27b. Capitulescence thyrse-like, very slender (infrequently with 1 or more prolonged branches); lower leaf blades crenate to crenate-serrate, the middle blades 0.5–2 (–2.5) cm wide; cypsela body 2.2–3 mm long
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26b. Cypsela body pubescent; capitula with 8–13 ray flowers; plants of mountains, cliffs, and northern river shores
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28a. Involucral bracts oblong to lanceolate, not glutinous, the middle ones 1.2–2 mm wide, green in large part; leaves of the stem below the capitulescence numbering 2–4 (–7) (in part)
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28b. Involucral bracts linear to narrow-lanceolate, glutinous, the surface shiny as if covered with varnish, the middle ones 0.7–1.2 mm wide, with chartaceous base and sides, green only at the apex and along the central band; leaves of the stem below the capitulescence numbering 5–40
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Each photo represents one species in this genus.