Solidago canadensis L.

Global description

Solidago canadensis is a large upright rhizomatous vivacious plant with a stem that is unbranched or only slightly branched. The leaves are simple, alternate, lanceolate and attenuated at both ends. The margin is entire on the basal leaves and strongly toothed on the upper leaves. The inflorescence is a large pyramidal panicle of a multitude of small yellow capitula.

General habit

Solidago canadensis is a large, robust, upright plant, 0.5 to 1.5 m (2 m) high.

Underground system

The taproot is more than 20 cm deep. Creeping, branching rhizomes develop at the base of the plant, from which aerial stems develop each year.

Stem

The stem is unbranched or only slightly branched at the base, then branches just below the inflorescence. The aerial stem is annual, dying after fruiting and developing again the following spring from rhizome buds. The stem is cylindrical, glabrous at the base and finely pubescent at the top.

Leaf

The leaves are simple, alternate and sessile. The blade is lanceolate to linear lanceolate, 5 to 14 cm long and 0.5 to 2 (4) cm wide. The apex is acute wedge-shaped and the base is long attenuated into a pseudo-petiole. The leaf blade is clearly marked by 3 parallel longitudinal veins. The margin is often entire for the leaves at the base and then gradually becomes more or less long-toothed. The lower face is downy and the upper face is short-pubescent to scabrous.

Inflorescence

The inflorescence is a large, upright, pyramid-shaped terminal panicle with secondary axes that are sometimes horizontal or pointing downwards. The capitula, which are very numerous (150 to 1300), are arranged on the upper side of the branches of the inflorescence.

Flower

The flower heads are golden yellow, borne on peduncles 3 to 3.5 mm long and 3 to 4 mm in diameter and surrounded by an involucre of imbricated bracts in 3 to 4 series, linear in shape with an obtuse apex. The peripheral florets are ligulate, few in number (8 to 14) and terminate in a ligule 1 to 1.5 mm long. They are arranged in a single raw and are female. The central florets are tubular, few in number (3 to 6), 2.2 to 2.8 mm long and hermaphrodite.

Fruit

The fruit is an achene 0.9 to 1.2 mm long, angular, topped by a pappus with 1 or 2 rows of scabrous hairs 2 to 2.5 mm long.

Origin

Solidago canadensis is native to North America (USA, Canada).

Worldwide distribution

This species was introduced from many countries as an ornamental plant and quickly became naturalised. It is found throughout Europe, India and South East Asia, as far as Australia and New Zealand. It is present and locally naturalised in South Africa.

https://www.gbif.org/species/5389029