Cirsium arvense (L.) Scop.

Global description

Cirsium arvense is a dioecious vivacious species, with long underground rhizomes and erect aerial stems. It grows in patches. The leaves are simple, alternate, sessile and oblanceolate in shape, with a smooth surface or one covered with araneous hairs and a wavy, irregularly lobed margin with spines. The top is spiny and the base attenuated. The inflorescence is a set of terminal flower heads arranged in a corymb. The involucre is more or less ovoid, made up of several series of identically shaped bracts, pointed at the apex. The flower heads are unisexual, tubular flowers with a pink to purple-red corolla, rarely white, ending in 5 linear lobes. The fruit is a yellowish achene topped by a pappus of pale white feathery bristles.

First leaves

The first leaves are simple, alternate, sessile and rosette-shaped. The blade is elliptical to oblanceolate, 2 to 6 cm long and 1 to 2 cm wide. The apex ends in a point. The margin is wavy and irregularly lobed, with numerous spiny tips. The faces are glabrous or finely woolly. The central vein is light green.

General habit

Cirsium arvense is an upright plant, 30 to 160 cm high, forming patches as buds develop from the creeping rhizomes.

Underground system

The main root is taprooted and can reach a depth of 2 to 5 m. The underground system comprises numerous trailing rhizomes.

Stem

The stem is erect, not very branched, not winged and not prickly. It is cylindrical, solid, hairless or finely woolly.

Leaves

The leaves are simple, alternate and sessile. The basal leaves are arranged in a rosette, while the stem leaves are smaller, spaced apart, with an attenuated but not decurrent base. The leaf blade is oblong, elliptical to oblanceolate, 3 to 30 cm long and 1 to 6 cm wide. The base is progressively attenuated and the apex is sharply pointed. The margin is very variably lobed, wavy and dotted with spines of varying size, the largest being 1 to 7 mm long. The upper face is glabrous or densely greyish tomentose, while the lower face is glabrous to finely tomentose. The leaves are dark green, with the midrib appearing distinctly light green.

Inflorescence

The inflorescence is a solitary terminal flower head or terminal group of capitulum arranged in a corymb. They are borne on a peduncle 0.2 to 7 cm long. The involucre is ovoid in flower, becoming campanulate in fruit, 1 to 2 cm high and in diameter, more or less glabrous or tomentose. The bracts are arranged in 6 to 8 series and are identical in shape, lanceolate, ending in a sharp point, 3 to 4 mm long and 1 mm wide, with narrow glutinous ridges on the underside and a non-membranous margin. They are often tinged with purple at the tip. The bracts are well imbricated, with only the tips spreading outwards. The flower heads are unisexual, made up of numerous pink, purple-red or rarely white florets, which clearly protrude above the involucre of bracts.

Flower

The peripheral florets differ little from the central florets. They are all tubular with a basal tube 10 to 15 mm long and 5 linear lobes 2 to 3 mm long.

Fruit

The fruit is a yellowish to brown, fusiform achene, 2 to 4 mm long, surmounted by a pappus of numerous feathery bristles 13 to 32 mm long, dirty white to light brown in colour.

Origin

Cirsium arvense is native to the whole of Europe and temperate to subtropical Asia, as far south as Japan.

Worldwide distribution

This species has been introduced throughout North America and the temperate part of South America (Paraguay, Uruguay, Chile, Argentina), South Africa, Australia, Tasmania and New Zealand.

https://www.gbif.org/species/3113414