calendula (L.) Levyns][Bayer code: none][CDFA list: A][CalEPPC: Red alert]
SYNONYMS: cape dandelion,
cape gold, Arctotis calendula L., Arctotheca calendulaceum
(L.) Lewin, Cryptostemma calendula (L.) Druce
DESCRIPTION: Rosette-forming perennial with creeping
stolons or winter annual, to 0.3 m tall. Capeweed
is often grown as an ornamental groundcover. Most plants in the
horticultural trade are derived from a single sterile individual
and reproduce vegetatively. However, noxious seed-bearing types
have been introduced into California and have escaped cultivation
in some areas. Seed-bearing plants typically colonize open sites
with exposed soils. Sterile plants sometimes escape cultivation,
but are much less invasive than seed-bearing plants. Capeweed
is perennial in areas with a mild frost-free mediterranean
climate, such as coastal California. Seed-bearing plants are annual
elsewhere, including capeweeds native range and southern
Australia, where it is an abundant pasture weed. Certain capeweed
populations in Australia have developed resistance to bipyridylium
herbicides. Handling plants can cause contact dermatitis on sensitive
individuals. Introduced from South Africa.
spoon-shaped, glabrous. First leaves appear opposite, narrowly
oblong with deeply lobed margins. Lobes broadly acute to rounded.
Terminal lobe larger than lateral lobes, typically rounded. Upper
surfaces sparse to moderately covered with white hairs. Lower
surfaces densely covered with white woolly hairs. Subsequent
leaves alternate, similar to first leaves.
Rosette leaves +/- oblanceolate, deeply pinnate- to +/- bipinnate-lobed,
5-25 cm long, 2-6 cm wide. Lobes irregularly toothed to lobed,
teeth and lobe apices +/- acute, often tipped with a short bristle.
Upper surfaces glabrous to moderately covered with fine white
cobweb-like hairs. Lower surfaces white, densely covered with
white woolly hairs. Leaves on flowering stems 0-few, alternate,
much reduced, sessile, clasping stem, pinnate-lobed to nearly
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and UNDERGROUND STRUCTURES: Stolons creeping, rooting at nodes, often vigorous.
One plant can spread to cover up to 18 m2 (200 ft2)
in 1-2 years.
FLOWERS: Most of year,
peaking March-June. Heads +/- 5 cm in diameter, solitary on hairy stalks
~ 15-20 cm long. Receptacle flat, lacks chaff (bracts).
Phyllaries strongly overlapping (imbricate) in 3-6 rows,
green, with membranous margins and tips curved backwards (reflexed),
covered with woolly hairs. Ray flowers sterile, less than 20.
Ray corollas 15-25 mm long, pale yellow in upper half,
sometimes darker yellow below, purple or greenish at the base.
Disk flowers dark purplish or yellow, numerous. Pappus
scales 6-8, +/- 1 mm long.
and SEEDS: Achenes ovate, flattened, ~2-4 mm long. Surface
longitudinally 3-5-ribbed, laterally wrinkled, but hidden
by a dense ball of long pale (pinkish-)brown woolly hairs.
CHARACTERISTICS: Plants break-apart rapidly when desiccated.
coastal and urban sites. Tolerates drought. Grows best on well-drained
soils. Plants are damaged by frosts a few degrees below freezing
and are killed by colder temperatures.
DISTRIBUTION: Escaped populations
are uncommon. North Coast, San Francisco Bay region. To 250 m
by seed and/or vegetatively from stolons. The biology of capeweed
is poorly understood. Seeds disperse with human activities, animals,
and probably wind. Seedlings tolerate dry conditions.
FAVORING/DISCOURAGING SURVIVAL: In pastures, mowing and close grazing can increase
the ratio of capeweed to desirable vegetation. Shallow
cultivation can eliminate seedlings.
Cape marigold or African daisy [Dimorphotheca sinuata DC.][Bayer
code: none] is a winter annual with orange to yellow ray flowers,
sometimes with violet tips or bases, and yellow disk flowers that has escaped
cultivation and may be confused with capeweed. Unlike capeweed,
cape marigold has phyllaries in 1 row, flowers that lack a pappus,
smooth and tubercled achenes without woolly hairs, foliage covered
with glandular hairs, and leaves that lack a dense covering of white
woolly hairs. Cape marigold occurs along roadsides and in disturbed
areas of the San Joaquin Valley, western South Coast Ranges, South Coast, and
Peninsular Ranges. To 1000 m (3300 ft). Introduced from South Africa.
Prevention: Capeweed was originally introduced to California
from a single sterile clone and primarily spreads vegetatively from horticultural
plantings. However, plants producing viable seed have been found from other
more recent introductions. To prevent spreading capeweed into sensitive wildland
habitat, use other noninvasive horticultural species when landscaping near the
urban wildland interface, preferrably native species. If capeweed must be used,
be sure to check that you are using the sterile clone that does not produce
Mechanical: Hand removal with a hoe has been one of the
primary methods used for capeweed eradication. Starting at the edge of a patch,
work inwards, removing plants rooted at the nodes on each stolon. Some resprouting
will occur from missed tubers or crowns, so a follow up removal will likely
be necessary. Broken stems may root if left on the soil surface in moist areas.
Where possible, tractor mounted scraper blades may also be used to remove dense
infestations. However, this results in complete disturbance of the plant community,
but may be efficient in badly infested areas.
Biological: There are no registered biological agents for
capeweed control and it appears to be rarely used by native California wildlife.
Some insects, diseases, and invertebrates may occasionally cause minor damage
to plants but with no long term adverse effects.
Chemical: A 3% v/v solution of glyphosate has been used
to control large infestations of capeweed. Repeated applications may be necessary
for complete eradication. A bypyridylium herbicide resistant biotype has been
reported from Australia but has not been reported to occur in California.
Prescribed fire: No information has been reported on the
use of fire for capeweed control.
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