Helianthus debilis
Helianthus floridanus
cucumberleaf sunflower, weak sunflower
Florida sunflower
decumbent to erect, glabrous, hirsute, or puberulent.
(green) erect, hispid to hispidulous.
mostly cauline; mostly alternate;
petioles 1–7 cm;
blades deltate-ovate, lance-ovate, or ovate, 2.5–14 × 1.8–13 cm, bases cordate to truncate or broadly cuneate, margins subentire to serrate, abaxial faces glabrate to hispid, not gland-dotted.
cauline; usually opposite or alternate, rarely whorled;
petioles 0–1 cm;
blades (1- or 3-nerved) lanceolate to elliptic or lance-ovate, 4–15 × 0.5–6 cm, bases rounded to cuneate, margins entire or serrulate (often undulate, often ± revolute), faces ± scabrous to tomentulose and gland-dotted (abaxial) or scabrous (adaxial).
9–50 cm.
2–15 cm.
hemispheric, 10–22 mm diam.
± hemispheric, 12–19 × 7–9 mm.
11–20;
laminae 12–23 mm.
10–20;
laminae 20–25 mm (abaxial faces gland-dotted).
30+;
corollas 4.5–5 mm, lobes usually reddish, sometimes yellow;
anthers dark, appendages dark (style branches usually reddish, rarely yellow).
90+;
corollas 4–5 mm, lobes usually reddish, sometimes yellow;
anthers dark brown or black, appendages dark (style branches yellow).
20–30, lanceolate, 8–17 × 1–3 mm, apices acute to long-attenuate, abaxial faces glabrous or ± hispid, not gland-dotted.
33–38, lanceolate, 5–9 × 1.5–3 mm, apices (at least outer) obtuse, abaxial faces hispidulous to hispid, gland-dotted.
1–3.
1–6.
2.5–3.2 mm, glabrous or sparsely hairy;
pappi of 2 lanceolate or lance-linear scales 1.2–2.5 mm.
2.5–3 mm, glabrous;
pappi of 2 aristate scales 1.5–2.2 mm.
7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded).
4.5–6 mm, entire or weakly 3-toothed (apices purplish, glabrate to puberulent, often gland-dotted).
= 34.
Helianthus debilis
Helianthus floridanus
Subspecies 5 (5 in the flora).
C. B. Heiser (1956) placed 8 subspecies in Helianthus debilis; he noted that alternative taxonomic treatments might recognize these in as many as three species, or expand the single species to include H. petiolaris. Later, Heiser et al. (1969) separated three of the subspecies as H. praecox. Isozyme data (R. P. Wain 1982, 1983; L. H. Rieseberg and M. F. Doyle 1989) show that all are closely related. Documented hybridization with H. annuus further complicates the situation. The treatment by Heiser et al. is followed here.
Helianthus debilis is adventive beyond the Atlantic and Gulf coasts of the United States.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Helianthus floridanus is similar to and intergrades with H. angustifolius, which has narrower leaves, and H. simulans, which is more robust and has longer leaves without undulate margins.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Stems decumbent; peduncles 9–20(–22) cm | → 2 |
1. Stems erect; peduncles (15–)20–50 cm | → 3 |
2. Stems glabrous or puberulent; leaf blades serrulate or shallowly, regularly serrate, abaxial faces sparsely, if at all, gland-dotted | subsp. debilis |
2. Stems hirsute; leaf blades deeply, irregularly serrate, abaxial faces densely gland-dotted | subsp. vestitus |
3. Leaves 8–14 cm; peduncles (relatively slender) 20–40 cm; discs 10–15(–17) mm diam | subsp. silvestris |
3. Leaves 2.5–9 cm; peduncles (not notably slender) 10–50 cm; discs 14–20 mm diam | → 4 |
4. Leaf blades usually deeply, irregularly serrate; peduncles 10–25(–30) cm; ray lami-nae 12–20(–22) mm | subsp. tardiflorus |
4. Leaf blades usually shallowly, regularly serrate; peduncles 25–50 cm; ray laminae (15–)20–23 mm | subsp. cucumerifolius |
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