cuckoo’s sorrel, red sorrel, sour dock, sour grass
Rumex acetosella L.
Sheep’s sorrel is a perennial plant native in open ground, short grassland and cultivated land mostly on acid, sandy soils throughout Britain. It is infrequent on calcareous soils. Sheep’s sorrel may sometimes be a troublesome weed in dry pastures and is considered to be an indicator of poor, sour, sandy soils and the absence of lime. In early surveys of Bedfordshire, Hertfordshire and Norfolk it was characteristic of acid sandy soils and light sandy loams but was never associated with chalk. Sheep’s sorrel occurs both in permanent grassland and in disturbed habitats such as arable land and burnt moorland, particularly on acid or peaty soils. It is a hater of lime and seedlings become chlorotic on calcareous soils.
There is evidence that sheep’s sorrel was a weed of crops in the Bronze Age. It is frequent on both grazed and ungrazed grassland and heathland but the plant itself is little grazed.
Sheep’s sorrel flowers from May to September. Male and female flowers are found on separate plants. The male flowers tend to be produced earlier than the female ones. The ultimately taller female inflorescences continue to elongate and develop after the male inflorescences have matured. The flowers are wind pollinated.
Younger populations tended to produce lighter seeds that germinated well. Fertilizer levels applied during growth of the parent plant also affected mean seed weight and germination level.
It is suggested that based on its seed characters sheep’s sorrel should persist for more than five years. In an acidic grassland with ant-hills present, sheep’s sorrel seeds were far less numerous in the ant-hill soil than in soil from the undisturbed sward. Seed kept in dry storage retained over 80% viability after 5 years. Seed buried in soil gave 14% germination after 5 years.
Improving the condition of the soil will help to get rid of this weed. An application of lime will be beneficial in this, as will manuring. Tillage operations, the hoeing of root crops and the removal of the creeping rootstocks will all help to reduce the weed. It is important that only pure crop seeds are sown.
Sheep’s sorrel is often locally dominant on heath after burning. It can become dominant soon after burning off the vegetation cover because it has the capacity to rapidly develop adventitious shoots from the shallow root system.