Crownbeard Verbesina encelioides (Cav.) A. Gray ssp. encelioides
Synonyms - Ximenesia exauriculata
Family: - Asteraceae
Names:
Verbesina because it has a leaf shape similar to plants in the Verbena genus.
Encelioides celebrates the 16th century naturalist Christopher Encel.
Crownbeard refers to the hairy inner seeds.
Other Names:
American Dogweed because it comes from America
Gold Weed because of its golden flowers.
Golden Crownbeard
South African Daisy
Wild Sunflower because it resembles a bushy Sunflower.
Summary:
An erect, branching, 30-150 cm tall annual with downy, greyish, triangular, toothed or lobed leaves that are dull green on top and densely hairy underneath. It has daisy like flowers with bright yellow petals and a yellow centre that form a globular seed head in spring and summer.
Description:
Cotyledons:
Two.
First leaves:
Opposite.
Leaves:
Opposite on lower stems and alternate towards the top.
Dull green on top, whitish due to dense hairs on underside.
Stipules - Leafy, ear-like appendage where petiole joins stem.
Petiole - Short, often broadly winged along its length.
Blade - 40-110 mm long by 25-60 mm wide. Thin. Somewhat triangular overall. Green on the topside and hairy underneath. Edges toothed or lobed. Tip pointed. Base abruptly tapered to almost square.
Stem leaves - Mostly alternate
Stems:
Dull green, 300 to 1500 mm tall, branching almost from the base. Hairy with dense, short, white hairs.
Flower stem - (peduncle) 250 mm long, leafless, erect.
Flower head:
Globular, 25-50 mm diameter. 2 rows of green, slender hairy bracts, 7-15 mm long underneath.
Usually single but occasionally in clusters on the ends of erect, long, leafless stalks (peduncles) to 250 mm long.
Involucre hemispherical.
Receptacle convex and pitted with non persistent scales.
Flowers:
Golden yellow and daisy like with 12-15 'petals' and a 25-50 mm diameter, yellow centre
Ovary -
Style - branches linear with shortly hairy, finely tapered tips.
"Petals" - Golden yellow, 10-20 mm long, lance shaped and in a single row around the flower. 3 toothed at the tips. Central florets are numerous, yellow, tubular and 5 lobed
Ray florets - With "petals" (ligulate). Female, fertile or sterile.
Disk florets - Yellow, bisexual, fertile, 5 toothed
Stamens -
Anthers - Obtuse at the base. Narrow acute appendage at the top
Fruit:
Achene.
Seeds:
Dark brown becoming olive white. Egg shaped, 5-8 mm long.
Outer seeds are thick, flattened, warty or roughly wrinkled and somewhat triangular, wingless and awnless.
Inner ones are hairy, egg shaped, winged and have 2 pointed bristles on top (which may be obscured by the wings or fall off).
Roots:
Branching taproot with many laterals.
Key Characters:
No milky latex.
Leaves toothed, petiolate and not clasping stem.
Lower leaves opposite.
Bracts and whole plant without glands.
Corolla of outer florets more than 8 mm long
Inner achenes winged and with a pappus of 2 bristles
Adapted from L. Murray
Biology:
Life cycle:
Annual. Seeds germinate in autumn or early winter and produce a rosette of leaves. Growth is slow until spring when the flowering stems emerge. Flowering starts in October and continues until it is killed by drought or it dies naturally in autumn. Seeding normally occurs in autumn.
Physiology:
Moderately drought resistant and will remain green when other plants have died off.
Reproduction:
By seed only.
Flowering times:
October to February.
Mainly spring and early summer in WA.
Late spring to autumn in western NSW.
Seed Biology and Germination:
Seed germinates in autumn and winter.
Vegetative Propagules:
None
Hybrids:
A number of sub species exist.
Allelopathy:
Population Dynamics and Dispersal:
It is spread by seed carried mainly by animals or on bags and clothing. The seed has bristles which help it attach to fur and fibres. Some is spread as a contaminant of feed and cereal grains. The seed is too heavy for significant spread by wind. Earth works and machinery contamination are common causes for movement and introduction to new areas.
It often occurs in clumps.
Origin and History:
Southern USA and Mexico.
First recorded in NSW in 1908.
Distribution:
ACT, NSW, NT, QLD, SA, VIC, WA (Geraldton to Mandurah).
Habitats:
Climate:
Temperate to sub tropical climates.
The densest infestations occur in the 800-900 mm rainfall zone.
Soil:
Prefers light or sandy to sandy loam soils, red earths or clay flats that concentrate summer rainfall.
Prefers disturbed soil.
Plant Associations:
Bimble Box, Mallee and Mulga.
Usually occurs in small clumps.
Significance:
Beneficial:
Honey.
Detrimental:
Toxic weed of roadsides, disturbed areas stock routes and some bushland areas.
Weed of Maize, Sorghum and Peanuts overseas.
Toxicity:
Very toxic but rarely eaten by stock. Sheep are most sensitive followed by cattle then pigs. Most field cases occur during periods of drought when little other feed is available or when the plants are mature.
There are high levels of nitrate in mature plants but symptoms are not typical of nitrate or nitrite poisoning.
It is mainly mature plants that are eaten and old plants appear to be more toxic than young ones. One case of poisoning has been reported from dry Crownbeard in holding yards.
It may cause pneumonia in sheep and cattle. In pigs it can cause gastroenteritis.
Symptoms:
Sudden death with few symptoms or bloat, rapid breathing and frothing at the mouth and nostrils then death.
Engorgement of the lungs with blood and fluid in the chest cavity
Treatment:
Provide alternative feed.
Legislation:
Noxious weed of parts of NSW.
Management and Control:
Control initial infestation with 1 L/ha clopyralid(300g/L) plus 0.25% wetting agent in winter before flowering.
Manually remove isolated plants
Increase levels of shade by planting tall growing perennial species.
Hormone herbicides and glyphosate provide control.
Metribuzin is registered for control of seedlings in some crops.
Thresholds:
Rarely a problem in crops in Australia.
Very low because of toxicity in pasture.
Eradication strategies:
For isolated plants, spot spray with 1 litre of Access in 60 litres of diesel. Spray 10 square metres of soil around each plant to help control the seed bank.
For more extensive infestations away from desirable broad leaved species, use 10 L/ha Tordon 75-D applied in winter then manually remove remaining plants in summer. This will leave grasses to protect the soil. Repeat in the following season.
Where bare area is desired use a mix of 10 L/ha atrazine(500g/L) plus 2 L/ha Spray.Seed plus 1% spray oil in early winter. Repeat as necessary.
In bushland situations, try 1 L/ha clopyralid(300g/L) in winter. This will often provide highly selective control but needs to be tested on local species.
Spot spraying with 1 litre glyphosate(450g/L) plus 250 mL Pulse Penetrant® in 100 litres water before seed set provides control of existing plants but requires repeating as new plants emerge.
Herbicide resistance:
None reported.
Biological Control:
None at present.
Related plants:
None in the same genus in Australia.
Plants of similar appearance:
Sunflower Helianthus annua is less bushy and has flowers with darker centres.
Ursinia (Ursinia anthemoides) is a much smaller more delicate plant and the flowers have dark centres.
Variable Groundsel (Senecio lautus) is generally smaller.
Dittrichia viscosa is perennial and somewhat more bushy
References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P120. Photo.
Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P680. Photo.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).
Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume 3. P143. Diagram.
Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P108. Photo.
Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #1045.1.