Erect robust perennial, herb, 0.5-2.5 m high. Fl. yellow, Jul to Dec or Jan. Garden weed, on roadsides, waste places.
Alternative Names. Anise, Sweet Fennel, Aniseed, Sweet Anise.
General Biology. Growth form. Herb. Life form. Perennial. Reproduction. Root fragments, seed. Dispersal. Soil, machinery, water, birds, rodents, clothing, garden waste and soil movement. Toxicity. Contact with the sap or oil can cause photo-sensitivity and/or dermatitis in cattle. Ingestion of oil can be toxic to humans. Seedbank persistence. Medium to long term. Fire response. Resprouts from base after fire.
Notes. Naturalised in temperate and tropical regions worldwide. Usually found in highly disturbed and/or open sites. Forms dense uniform stands where it outcompetes other plant species for light, nutrients and water. Can prevent re-establishment of native plants and alter the composition and structure of communities. Possibly allelopathic. Alters fire regimes by building an intense fast moving fire, although it does not burn well in spring. Prefers well drained, sandy soils. Tolerant of frost, drought, water logging and semi-aridity. Mature plants have a large deep taproot with many lateral roots. During a growing season plants usually include a mixture of living and dead hollow stems (canes). Initial growth during winter and spring is slow, then becomes rapid in early summer. Flowering stems die during late autumn and early winter, although some remain alive and begin to produce new leaves with the onset of rain. Plants generally do not flower until 18 months to 2 years old. Flowers are monoecious (have both male and female parts) and are insect-pollinated. With prolific seed production and high seed viability, it rapidly establishes a persistent seedbank. One plant can produce thousands of seed in the first year, seed output can then increase greatly in the second year.
Additional information. Origin. Europe, Asia. History of use/introduction. Ornamental, spices, medicines.
Suggested method of management and control. Persistent and difficult to eradicate. Manual methods are most effective for small and/or isolated infestations. Otherwise, spot spray with 1.5% glyphosate or metsulfuron methyl 0.7 g/10 L (20 g/ha) + Pulse®. Apply in spring just before flowering. Follow up control of seedlings. Combination of burning followed by spraying may be effective. Cutting or slashing temporarily reduces heights, but plants readily resprout. Repeated cutting may have more impact by helping to exhaust the taproot over time, however, intervals between cuts must be short. Cutting prior to spraying does not generally increase the effectiveness of herbicides. Read the manufacturers' labels and material safety data sheets before using herbicides. For further information consult the Australian Pesticides and Veterinary Medicines Authority to determine the status of permits for your situation or state.
Legend: Y = Yes, regularly, O = Occasionally, U = Uncertain, referred by others but not confirmed.