Helianthus laciniatus
Helianthus silphioides
alkali sunflower
Ozark sunflower, rosinweed sunflower
erect, usually strigose or hispid to glabrate.
erect, hispid to strigoso-hispid proximally, glabrate distally.
cauline; opposite or alternate;
sessile;
blades (green or grayish, 1- or 3-nerved) lanceolate, 5–9 × 0.5–3.5 cm, bases ± cuneate, margins entire or irregularly toothed to lobed, faces strigose to strumose, gland-dotted (adaxial sometimes glaucous).
basal and cauline; mostly opposite;
petioles 0.1–5.5 cm;
blades ovate to broadly ovate or suborbiculate, 7–15 × 4.5–15 cm, bases rounded to truncate or ± cuneate, margins entire or crenate to serrate, abaxial faces usually scabrous, sometimes ± strigose (hairs on midribs to 1 mm), not gland-dotted (cauline 9+ pairs proximal to heads, smaller).
4–13 cm.
0.5–10 cm.
hemispheric, 10–24 mm diam.
hemispheric, 10–20 mm diam.
14–20;
laminae ca. 8–11 mm.
8–13;
laminae 15–20 mm (abaxial faces not gland-dotted).
40+;
corollas 4.8–5.8 mm, lobes reddish;
anthers purplish, appendages reddish (style branches yellow).
75+;
corollas 6–7 mm, lobes reddish;
anthers dark, appendages dark (style branches yellow).
16–21, lanceolate, 6–7.5 × 1.8–2.5 mm (often subequal), (margins ciliate) apices acute, abaxial faces hispidulous or strigose to glabrate, gland-dotted.
16–23, oblong to obovate, 8–10 × 3–5 mm, (margins ciliolate) apices obtuse to acute, sometimes mucronate, abaxial faces glabrous or glabrate.
1–9.
3–15+.
2.7–3.5 mm, glabrate;
pappi of 2(–3) aristate scales 1.4–2.5 mm.
3–4 mm, glabrous or distally puberulent;
pappi of 2 aristate scales 2.5–2.7 mm.
7–7.8 mm, entire or 3-toothed (apices obtuse to acute, hispid-ciliate to glabrate).
9–10 mm, entire or ± 3-toothed.
= 34.
= 34.
Helianthus laciniatus
Helianthus silphioides
Helianthus laciniatus reaches the northern extent of its range in New Mexico and Texas; it is relatively common in the Chihuahuan Desert areas of Mexico. It is similar to H. ciliaris; it usually has hairy stems as well as denser leaf indument that includes a greater number of subsessile, glandular hairs.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Similar to Helianthus atrorubens, H. silphioides is distinguished by shorter hairs (less than 2 mm) on stems proximally and on abaxial leaf midveins, and by petioles of basal leaves less than 1/2 lengths of blades and winged less than 1/2 their lengths. As befits the name, specimens of H. silphioides (and also H. atrorubens) are not infrequently misidentified as species of Silphium.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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