Helianthus exilis

A. Gray

Proc. Amer. Acad. Arts 6: 545. 1865.

Common names: Serpentine sunflower
Treatment appears in FNA Volume 21. Treatment on page 150. Mentioned on page 143, 149.

Annuals, 30–100 cm. Stems (often reddish) erect, hairy. Leaves mostly cauline; mostly alternate; petioles 0.7–2.5 cm; blades lance-linear to lanceovate or ovate, 3–15 × 0.5–3 cm, bases cuneate, margins usually entire or shallowly serrate, abaxial faces glanddotted. Heads 1–7. Peduncles (1–) 3–13 (–20) cm. Involucres hemispheric, 15–20 mm diam. Phyllaries 12–17, lanceolate, 8–17 × 3–4 mm, apices narrowed gradually, abaxial faces hirsute. Paleae 9.5–10 mm, 3-toothed (middle teeth surpassing discs, apices greenish or yellowbrown, glabrous). Ray-florets 10–13; laminae 14–20 mm. Disc-florets 50+; corollas 4–6 mm, lobes reddish; anthers reddish purple, appendages usually purplish (style-branches reddish or yellow). Cypselae (2.5–) 3–3.5 (–4) mm, glabrate; pappi of 2 lanceolate scales 1.7–2.7 mm. 2n = 34.


Phenology: Flowering summer–early fall.
Habitat: Gravelly streamsides on serpentine
Elevation: 100–1400 m

Discussion

Of conservation concern.

Helianthus exilis is very similar morphologically to H. bolanderi and is often included in it; there are discrete differences between the two for fatty acid composition (C. E. Rogers et al. 1982) as well as some molecular markers (L. H. Rieseberg et al. 1988). It is listed as of concern by the California Native Plant Society.

Selected References

None.

Lower Taxa

None.
... more about "Helianthus exilis"
not tailed +, rounded +  and obtuse +
reddish purple +
pale +  and dark +
connate +  and distinct +
narrowed +
subequal +
scarious +
usually ovate +  and lanceolate +
usually deltate +  and lanceolate +
spiciform +, paniculiform +  and corymbiform +
indeterminate +  and determinate +
Edward E. Schilling +
A. Gray +
cuneate +
3 cm30 mm <br />0.03 m <br /> (15 cm150 mm <br />0.15 m <br />) +
lance-linear;lanceovate or ovate +
0.5 cm5 mm <br />0.005 m <br /> (3 cm30 mm <br />0.03 m <br />) +
winged;ribbed;winged;ribbed +
tuberculate +  and rugose +
barbellulate +  and barbellate +
Serpentine sunflower +
reddish +  and yellow +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
compressed +  and obpyramidal +
fertile +  and bisexual +
fertile +  and bisexual +
100–1400 m +
hairy +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Gravelly streamsides on serpentine +
in more or less corymbiform , paniculiform or spiciform , arrays +  and singly +
indeterminate +
homogamous +  and heterogamous +
each +  and sessile +
1.5 cm15 mm <br />0.015 m <br /> (2 cm20 mm <br />0.02 m <br />) +
hemispheric +
1.4 cm14 mm <br />0.014 m <br /> (2 cm20 mm <br />0.02 m <br />) +
sessile +  and petiolate +
triangular +
serrate +  and entire +
2-carpellate +
3-toothed +
0.95 cm9.5 mm <br />0.0095 m <br /> (1 cm10 mm <br />0.01 m <br />) +
persistent +
coroniform +
13 cm130 mm <br />0.13 m <br /> (20 cm200 mm <br />0.2 m <br />) +
3 cm30 mm <br />0.03 m <br /> (13 cm130 mm <br />0.13 m <br />) +
0.7 cm7 mm <br />0.007 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
Flowering summer–early fall. +
0.8 cm8 mm <br />0.008 m <br /> (1.7 cm17 mm <br />0.017 m <br />) +
12 +  and 17 +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
Proc. Amer. Acad. Arts +
bearing subulate enations +, hairy +  and bristly +
flat;slightly convex +
lanceolate +
0.17 cm1.7 mm <br />0.0017 m <br /> (0.27 cm2.7 mm <br />0.0027 m <br />) +
exalbuminous +
procumbent +  and decumbent +
appendaged +  and truncate +
hirsutulous +  and glabrous +
papillate +
Undefined (tribe Undefined) subtribe Lagasceinae +
Helianthus exilis +
Helianthus +
species +
campanulate +
toothed +  and entire +
300 cm3,000 mm <br />3 m <br /> (500 cm5,000 mm <br />5 m <br />) +
30 cm300 mm <br />0.3 m <br /> (100 cm1,000 mm <br />1 m <br />) +
2 cm20 mm <br />0.02 m <br /> (20 cm200 mm <br />0.2 m <br />) +
shrub +  and subshrub +