Taxonomy

Solidago gigantea Aiton, Hort. Kew. [W. Aiton] 3: 211. 1789.

Common synonyms

Solidago serotina Retz. var. gigantea (Aiton) A.Gray Proc. Amer. Acad. Arts 17: 196. 1882.

Common name

Giant goldenrod, late goldenrod, smooth goldenrod

Description

Propagule or dispersal unit is the fruit with pappus. Fertile part 1-2 mm long, 0.2-0.5 mm wide, in side view widest in upper part (obovoid) or widest in the middle, +/- straight, the upper (apical) end narrowing, rarely suddenly cut off (truncate) (by misinterpretation), in cross-section flattened, rarely angular (prismatic), basal scar (carpopodium) pronounced and well-differentiated, central, beak (=thinner sterile stalk between seed and pappus) absent, wings absent, fruit surface light brown or straw, smooth (except at cellular level), with simple straight hairs, thickened margin absent, longitudinal ribs present, 4-10, their surfaces smooth, with simple straight hairs.

Pappus type bristles / hairs, pappus elements all +/- similar, up to 2-3.5 mm long, in one row, pappus elements numerous, persistent, the individual bristles rough / serrated (barbellate), +/- equal width along length, white / translucent.

Notes: The three Solidago species included in this key can be differentiated by the size of their fruits. Solidago canadensis has a fertile part of less than 1 mm in length, Solidago gigantea 1-2 mm, and Solidago virgaurea 2-4 mm.

Ecology

Perennial herb, fruits wind-dispersed. Temperate areas. Tolerates wide range of soil conditions but needs open areas. Particularly common in grasslands, edges of wetlands and river margins, forest edges, rail- and roadsides, and urban areas.

Native range

Canada, United States.

Introduced range

Widespread through most of Europe, Korea, Japan.

Weed status within Australia

WA Declared Pest s12 (C1 Prohibited).

Past interceptions (Australia): origins

Other or unidentified species of the genus from Canada, United States, Spain, France, Slovakia, Hungary, UAE, Sri Lanka, Japan, Korea, Thailand.

Past interceptions (Australia): commodities

Other or unidentified species of the genus in/on nursery stock, machinery and parts, new vehicles, curry leaves, new tyres.