Helianthus debilis
Helianthus heterophyllus
cucumberleaf sunflower, weak sunflower
variableleaf sunflower, wetland sunflower
decumbent to erect, glabrous, hirsute, or puberulent.
erect, usually hispid to ± hirsute.
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.
mostly basal; mostly opposite;
petioles 0–3 cm (broadly winged);
blades (3-nerved distal to bases) ovate or lanceolate to spatulate, 6–28 × 1.2–4.3 cm, bases cuneate, margins entire (often revolute), abaxial faces hispid to ± hirsute, not gland-dotted (cauline leaves relatively few, narrowly lanceolate to linear, much smaller).
9–50 cm.
10–15 cm.
hemispheric, 10–22 mm diam.
broadly hemispheric, 15–25 mm diam.
11–20;
laminae 12–23 mm.
12–18;
laminae 14–36 mm (abaxial faces not gland-dotted).
30+;
corollas 4.5–5 mm, lobes usually reddish, sometimes yellow;
anthers dark, appendages dark (style branches usually reddish, rarely yellow).
100+;
corollas 5.5–6.5 mm, lobes reddish;
anthers purplish, apendages purplish (style branches usually reddish).
20–30, lanceolate, 8–17 × 1–3 mm, apices acute to long-attenuate, abaxial faces glabrous or ± hispid, not gland-dotted.
24–30, lanceolate to lance-ovate, 8–13 × 2–5 mm, (margins sometimes ciliate) apices acute to short-acuminate or acuminate, abaxial faces sparsely hispid to glabrate.
1–3.
1–3(–5).
2.5–3.2 mm, glabrous or sparsely hairy;
pappi of 2 lanceolate or lance-linear scales 1.2–2.5 mm.
4–5 mm, glabrate;
pappi of 2 aristate scales 1.7–2.5 mm plus 1–3 deltate scales 0.5–1.5 mm.
7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded).
7–9 mm, 3-toothed (apices purplish).
= 34.
Helianthus debilis
Helianthus heterophyllus
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 heterophyllus is found on the Atlantic and Gulf coastal plains. The cauline leaves are usually abruptly reduced relative to the basal leaves; individuals sometimes have relatively large cauline leaves.
(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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