Arctotheca calendula

(Linnaeus) Levyns

J. S. African Bot. 8: 284. 1942.

WeedyIntroducedIllustrated
Basionym: Arctotis calendula Linnaeus Sp. Pl. 2: 922. 1753
Synonyms: Cryptostemma calendula (Linnaeus) Druce
Treatment appears in FNA Volume 19. Treatment on page 197.

Plants usually stoloniferous. Leaves obovate, (2–) 5–20 (–30+) × (1–) 2–5 (–7) cm, margins pinnatisect (lyrate to runcinate), remotely prickly, abaxial faces white-pannose, adaxial faces sparsely puberulent to arachnose, usually glandular as well. Heads 4–7 cm diam. (across the rays). Phyllaries: outer reflexed, apices mucronate, white-woolly; inner appressed, margins hyaline, apices rounded, glabrous. Ray-florets 11–17 (–25); corolla laminae abaxially greenish to purplish, adaxially yellow (drying to basally ochroleucous, apically blue, forming bull’s eye around disc), 10–25 × 2–4 mm, sparsely puberulent, glandular. Disc-florets: corollas yellow proximally, bluish distally. Cypselae dark-brown, 3 mm, densely woolly; pappi ca. 0.5 mm (usually hidden by hairs on cypselae).


Phenology: Flowering Oct–Aug.
Habitat: Roadsides, old fields, other disturbed habitats
Elevation: 0–300 m

Distribution

V19-232-distribution-map.gif

Introduced; Calif., Africa

Discussion

Most populations of Arctotheca calendula are sterile and spread aggressively by stolons; at least three populations in the flora are fertile and highly invasive. The species is listed by the California Exotic Pest Plant Council (CalEPPC) as a weed with the potential to spread explosively (Red Alert, CDFA A).

Selected References

None.

Lower Taxa

None.
... more about "Arctotheca calendula"
sparsely puberulent +  and arachnose +
obtuse +  and acute +
glabrous +  and white-woolly +
scarious +
less ovate +  and lanceolate +
indeterminate +  and determinate +
Alison McKenzie Mahoney +
(Linnaeus) Levyns +
decurrent +
Arctotis calendula +
compound +  and simple +
obovate +
actinomorphic +
bluish +  and yellow +
yellow +, abaxially greenish +  and purplish +
1 cm10 mm <br />0.01 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
2mm +  and 4mm +
prismatic +  and obovoid +
fertile +  and bisexual +
Calif. +  and Africa +
0–300 m +
woolly +  and villous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Roadsides, old fields, other disturbed habitats +
indeterminate +
4 cm40 mm <br />0.04 m <br /> (?) +  and 7 cm70 mm <br />0.07 m <br /> (?) +
heterogamous +
each +  and sessile +
1 cm10 mm <br />0.01 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
hemispheric;campanulate +
3-toothed +
20 cm200 mm <br />0.2 m <br /> (30 cm300 mm <br />0.3 m <br />) +
5 cm50 mm <br />0.05 m <br /> (7 cm70 mm <br />0.07 m <br />) +
5cm;20cm +
cauline +  and basal +
obovate +
2 cm20 mm <br />0.02 m <br /> (5 cm50 mm <br />0.05 m <br />) +
lanceolate +  and deltate +
usually pinnatifid +  and pinnatisect +
2-carpellate +
persistent +
coroniform +
0.5 cm5 mm <br />0.005 m <br /> (?) +
Flowering Oct–Aug. +
J. S. African Bot. +
sterile +  and fertile +
bearing subulate enations +, hairy +  and bristly +
3 +  and 5 +
7 +  and 9 +
exalbuminous +
Weedy +, Introduced +  and Illustrated +
creeping to more or less erect +  and decumbent +
prostrate +  and ascending +
appendaged +  and truncate +
cylindric +  and dilated +
Cryptostemma calendula +
Arctotheca calendula +
Arctotheca +
species +
20 cm200 mm <br />0.2 m <br /> (30 cm300 mm <br />0.3 m <br />) +
8 cm80 mm <br />0.08 m <br /> (20 cm200 mm <br />0.2 m <br />) +