Cow parsley
Other names
Wild chervil, hedge parsley, keck, wild beaked parsley
Latin names
Anthriscus sylvestris (L.) Hoffm., (Chaerophyllum sylvestre, Cerefolium sylvestre)
Weed Type
Perennial Broad-leaved Weeds
Occurrence
Cow parsley is variously described as an annual, a biennial, or as a short-lived monocarpic or polycarpic perennial. It is native in grassy places, hedgerows and wood-margins, and is abundant through most of Britain. Cow parsley is most frequent in soils of pH 7.0. It does not occur in waterlogged soils or sites susceptible to drought. Although it is common in hedge-bottoms and field edges it does not spread far into the arable field. Cow parsley is only found as seedlings on arable land. Populations exhibit some variation in morphology.
The plant is grazed by cattle, although it is of low nutritional value. The willow carrot aphid (Cavariella aegopodii) may overwinter on cow parsley.
Biology
Cow parsley flowers from April to June. The flowers are insect pollinated. The fruits mature in late-June to July and gradually fall off from July to September. Some can persist on the senesced flower stem into the winter. There may be 800 to 10,000 seeds per plant.
The embryos in ripe seeds are immature and require a period of after-ripening. Chilling over winter results in synchronous germination in spring. Seed sown in the field and stirred periodically emerged from January to May with no seedlings outside this period. The majority of seedlings emerged in the first year with few seedlings appearing in subsequent years. Seed sown into short turf in October emerged from February to May with a peak in late-February. Only 11% of the seedlings survived through the summer.
Seedlings form leaf rosettes but do not flower in the first year. Once the plants reach a minimum size, vernalisation can lead to flowering. During early growth, a high proportion of resources are allocated to root growth. The plant produces a thick taproot up to 2 m long. The root and its crown overwinter. Cow parsley perennates by buds in the axils of the basal leaves that develop into new plants once the old flower stem dies.
Persistence and Spread
Cow parsley does not appear able to form a persistent seedbank in soil.
The seeds have no obvious dispersal mechanism. Seeds of cow parsley growing in field margins are dispersed mainly within 1 m of the source. A few are found up to 3 m from the parent plant. Reproduction by seed occurs mainly after soil disturbance. The seeds do not float in water.
Vegetative reproduction occurs with the production of side rosettes from buds in the leaf axils of the root crown. Cutting down the flower stem before it matures stimulates abundant bud production. The buds develop taproots and the new plantlets eventually separate from the main root. Dense populations can develop in this way. Vegetative reproduction is most important in standing vegetation.
Management
To prevent cow parsley setting seed, mow hay early and cut plants down in pasture. In roadside verges, increased cutting frequency reduced the incidence of cow parsley. The cutting of immature stems delays flowering and depletes food reserves in the roots but stimulates the production of flowering shoots from axillary buds. Cutting plants down at flowering induces side shoot production but no secondary flower stems develop. Repeated cutting, 3-6 times per year, may give short-term control. Spring grazing will decrease cow parsley populations. The plant is also sensitive to trampling.
Updated November 2007.