Weeds - Identification of Injurious Weeds (PB4192)

SPEAR THISTLE
Cirsium vulgare

Other common names: Scotch Thistle, Bell Thistle

Mature plant

Young plant

Cirsium vulgare

Spear Thistle

A, upper half of radical leaf, in outline, hairs omitted; B, flowering branch; C, upper part of flower cut away to show the stamens. Not to scale.

Young Plant:

Seedling plants appear from autumn until April in pasture and on bare ground. The cotyledons differ from those of creeping thistle in that they are borne on short stalks. The true leaves are also longer and more bristly with a downy appearance to the upper surfaces. The seedling plants quickly form rosettes which remain for at least one year before producing lowering stems.

Adult plant:

The flowering stems begin to emerge from the rosettes

when the basal leaves reach 15-30cm in length. These stems typically reach 30-100cm in height, but taller specimens occur. Stems are cottony or minutely hairy, bearing discontinuous wings and leaves which are also spiny and deeply lobed.

From July onwards plants produce large purple flower heads 3-5cm long by 2-5cm across, in loose clusters forming the stereotype image of a thistle. The flowering stems die back after producing seeds.

Other thistle species not prescribed in the Weeds Act 1959:

Marsh thistle Cirsium palustre

This more closely resembles spear thistle than creeping thistle, but has continuous, spiny wings along the stem.

The thistles listed below are not readily confused with creeping or spear thistle but special care should be taken not to damage these uncommon species:

Tuberous thistle Cirsium tuberosum Very rare perennial species of calcareous grassland in Wiltshire, Gloucestershire and Cambridgeshire made extinct in 1974 but re-introduced since 1987.

Melancholy thistle Cirsium heterophyllum/helenoides

An uncommon erect perennial plant of damp northern meadows, woodland edges and verges. Leaves unlobed, green above, whitish and cottony beneath, elliptical with a tapering point. The margins toothed or with soft spines. The stem is grooved, winged and cottony, bearing large usually solitary purple flowering heads.

Carline thistle Carlina vulgaris

A biennial plant of short calcareous grassland with very spiny leaves, cottony beneath with a short unspined flowering stem, 10-20cm, rarely up to 60cm. The flowering head is ringed by horizontally extended straw coloured rays.

Musk thistle Carduus nutans

An annual or biennial species of calcareous grassland with flowering stems 100cmin height, discontinuously winged. The large flowering heads are usually solitary and drooping.

Meadow thistle Cirsium dissectum

A local perennial plant up to 80cm high resembling a slender melancholy thistle, distributed through the southern half of lowland England and Wales to north-east Yorkshire.

Dwarf thistle Cirsium acaule

A stemless perennial thistle with a solitary flower head borne in the centre of the leaf rosette. Found on short and calcareous grassland in south and east England to Yorkshire.

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