Rudbeckia triloba
Rudbeckia sect. Rudbeckia
brown-eyed susan, thin-leaf coneflower, three-leaf coneflower, three-lobed coneflower
glabrate to hirsute or strigose (hairs 1–2 mm, basal retrorse, others spreading).
green.
blades ovate to subcordate or elliptic (not lobed), margins serrate, apices acute to acuminate, faces hirsute to strigose;
basal petiolate, 10–30 × 2–8 cm, bases truncate or rounded to cordate;
cauline petiolate or sessile, ovate to elliptic, proximal usually 3–5-lobed, 2–20 × 1.5–8 cm (smaller, fewer lobed distally), bases rounded to attenuate, sometimes clasping.
green, not glaucous;
basal (usually withering before flowering) usually petiolate, blades linear, lanceolate to ovate, or elliptic to oblanceolate, sometimes lobed, bases attenuate, cuneate, or rounded, margins entire, dentate, or serrate, apices acute to obtuse, faces glabrous or hairy, sometimes gland-dotted;
cauline usually petiolate (at least proximal), distal usually sessile, blades linear or ovate to pandurate, sometimes lobed, lobes 3(–5), bases auriculate, attenuate, or cordate, margins entire or serrate, apices acute to obtuse, faces glabrous or hairy, sometimes gland-dotted.
conic to subhemispheric;
paleae 5–6.5 mm, apices cuspidate (tips awnlike, 1.5+ mm), glabrous.
usually conic to hemispheric, rarely columnar;
paleae surpassing cypselae, margins sometimes ciliate, apices obtuse or rounded to acute or attenuate to apiculate, faces glabrous or hairy abaxially.
8–15;
laminae (corollas yellow to yellow-orange with basal maroon splotches) linear to oblanceolate, 8–30 × 3–8 mm, abaxially sparsely strigose.
6–25+;
corollas usually yellow-orange proximally, yellow distally, sometimes with basal maroon splotch (orangish red to maroon in R. graminifolia).
150–300+;
corollas yellowish green basally, otherwise brown-purple, 3–4 mm;
style branches ca. 1.2 mm, apices obtuse to rounded.
50–800+;
corollas proximally yellow to yellowish green, distally usually brown-purple, lobes sometimes yellowish or greenish;
anther appendages sometimes gland-dotted;
styles 3–5+ mm, branches 1–1.8 mm, proximal 1/2–4/5 stigmatic, apices acute to rounded.
to 1.5 cm (faces moderately hirsute).
in 2(–3) series.
(10–30) in paniculiform arrays.
borne singly or in loose, corymbiform to paniculiform arrays.
1.9–2.8 mm;
pappi coroniform, to 0.2 mm.
1.5–3.5(–4) mm;
pappi usually coroniform (sometimes cypselae each with glandular hairs around apices in R. heliopsidis).
8–15 × 10–20 mm.
8–30 × 5–25 mm.
= 19.
Rudbeckia triloba
Rudbeckia sect. Rudbeckia
Varieties 3 (3 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 9 (9 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Cauline leaves (at least some) 5–7-lobed (Florida, Kentucky, North Carolina, Virginia) | var. pinnatiloba |
1. Cauline leaves (at least some) 3-lobed | → 2 |
2. Ray laminae 8–17 mm; discs 10–15 mm diam. (20–100 m; relatively widespread) | var. triloba |
2. Ray laminae 18–30 mm; discs 15–20 mm diam. (100–1200 m; Iowa, Kentucky, North Carolina, Tennessee) | var. rupestris |
1. Leaves 0.2–1 cm wide (grasslike, lengths 10+ times widths); rays orangish red to maroon; Florida panhandle | R. graminifolia |
1. Leaves (0.4–)1–15 cm wide (if less than 1 cm wide, lengths less than 10 times widths); rays yellow to yellow-orange (at least distally); e North America | → 2 |
2. Annuals, biennials, or perennials (taprooted or roots fibrous); pappi 0 or coroniform (to 0.1 mm) | → 3 |
2. Perennials (usually rhizomatous and/or stoloniferous, roots fibrous, caudices sometimes woody); pappi 0 or coroniform (0.1–0.5 mm; sometimes cypselae each with glandular hairs around apices in R. heliopsidis) | → 4 |
3. Stems and leaves coarsely hispid to hirsute; style branch apices subulate; e NorthAmerica | R. hirta |
3. Stems and leaves softly pilose to woolly; style branch apices acute to obtuse; Alabama, Florida, Georgia, South Carolina | R. mollis |
4. Proximal cauline leaves elliptic or ovate, usually 3(–5)-lobed; paleae cuspidate (tips awnlike, 1.5+ mm) | R. triloba |
4. Proximal cauline leaves elliptic, linear, spatulate, or ovate, rarely lobed (3–5–lobed in R. subtomentosa); paleae acute, obtuse, or rounded | → 5 |
5. Stems and leaves densely hirsute; proximal cauline leaves 3(–5)–lobed; heads (usually 8–25) in loose, corymbiform to paniculiform arrays | R. subtomentosa |
5. Stems and leaves glabrous or sparsely to moderately hairy; proximal cauline leaves not lobed; heads borne singly or (2–12) in corymbiform arrays | → 6 |
6. Leaves: abaxial faces glabrous or hirsute to strigose (not gland-dotted); paleae: abaxial tips usually glabrous, rarely pilose | → 7 |
6. Leaves: abaxial faces glabrous or strigose and gland-dotted; paleae: abaxial tips canescent or strigose, sometimes gland-dotted as well | → 8 |
7. Plants stoloniferous (rosettes forming at stolon apices; stem branches spreading); basal leaves lanceolate to broadly ovate or elliptic | R. fulgida |
7. Plants not stoloniferous (rosettes at bases of aerial stems; stem branches ascending); basal leaves linear to narrowly spatulate | R. missouriensis |
8. Leaf blades elliptic, lanceolate, or ovate (flat); heads usually (4–8) in ± corymbiform arrays, sometimes borne singly; rays 6–12 (± spreading); pappi coroniform, to 1.5 mm (sometimes cypselae each with glandular hairs around apices); Alabama, Georgia, North Carolina, South Carolina, Virginia | R. heliopsidis |
8. Leaf blades elliptic, lanceolate, or ovate (± conduplicate); heads usually borne singly; rays 12–25 (reflexed); pappi coroniform, to 0.5 mm; midwestern and sc United States | R. grandiflora |
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