- Name also: Stinking Groundsel, Sticky Ragwort (USA)
- Family: Daisy Family – Compositae, subfamily Asteroideae
(formerly Aster Family – Asteraceae)
- Growing form: Annual herb.
- Height: 20–50 cm (8–20 in.). Stem branchless–branching from top, quite sturdy, densely tomentose and glandular-haired. With strong fragrance.
- Flower: Single flower-like approx. 6–10 mm (0.24–0.4 in.) capitula surrounded by involucral bracts. Capitula flowers yellow, ray-florets tongue-like, often curled up; disc florets tubular, small. Stamens 5. Pistil of 2 fused carpels. Involucre broadly funnel-shaped, involucral bracts 1 row, lanceolate, green, usually with black tips; outer bracts 3–8 at base of involucre, 2–4 mm long, very narrow, usually entirely green, spreading. 5–25 capitula borne in a lax corymbose cluster.
- Leaves: Alternate, lower short-stalked, upper stalkless, but not amplexicaul. Blade obovate, pinnately lobed, quite thick, covered in sticky glandular hairs, lobes toothed.
- Fruit: Cylindrical, ridged, glabrous, brown, approx. 3–4 mm (0.12–0.16 in.) long achene, tip with unbranched hairs.
- Habitat: Railways, roadsides, sand pits, wasteland, streets, fields, sandy shores, rocky outcrops, sea-shores.
- Flowering time: July–September.
Modern Finns may think of sticky groundsel as a common-or-garden weed in open land, but in fact it is quite a recent arrival. Its home is the scree beds of the Alps, from where it has spread to Finland with traffic, first to southern Finnish harbour areas and then via St Petersburg to eastern Finland. It was first observed in Finland at the end of the 19th century and by the turn of the century it was already growing in several places. It did not begin to take great strides, however, until much later. This spread seems to be accelerating even today and it will doubtless expand and move into new areas over the coming decades. Just as its territory is expanding, so it seems to be expanding its life span – the species has already begun to adapt to Finnish conditions. Global warming will only help sticky groundsel.
Sticky groundsel has characteristic glandular hairs which secrete a substance that is as sticky as fly paper and by the end of summer it is quite a mess with all the dust, sand, small insects, hairs, feathers, downy seeds, its own cypselas, candy wrappers and who knows what else that have stuck to it. In rail yards and storage areas the plant can be completely black with coal dust and soot. Sticky groundsel is not bothered by getting dirty, however, and it grows and flowers without any problems, producing its seed at the turn of summer and autumn. The plant likes to grow in habitats such as railway embankments, which radiate heat on sunny days. It has managed to travel to the northern terminus of the Finnish rail system, although it is rare in Lapland. It has travelled with the wind to roadsides, waste ground streets and yards. Sometimes it grows as a weed on cultivated ground and quite often by the coast or on rocky outcrops, where it might join heath groundsel (S. sylvaticus), which is native to Finland, and on fields it might link up with common groundsel (S. vulgaris). Like its close relatives, sticky groundsel can’t really stand being crowded by other plants and disappears as the competition increases.