- Family: Daisy Family – Compositae, subfamily – Cichorioideae (formerly Chicory Family – Cichoriaceae)
- Growing form: Annual herb.
- Height: 30–100 cm (12–40 in.). Stem often branched, base abundantly haired, upper part usually sparsely hairy.
- Flower: Single flower-like capitula approx. 1 cm (0.4 in.) broad, surrounded by involucral bracts. Capitulum flowers (8–15) pale yellow, tongue-like, tip 5-toothed. Stamens 5. Gynoecium composed of 2 fused carpels. Involucre narrowly elliptic, involucral bracts in 2 rows, inner bracts erect, equal height, narrow, hard, glabrous, green, outer bracts very small. Capitula borne in a terminal corymbose cluster.
- Leaves: Alternate, lowest stalked, upper short-stalked–stalkless. Lowest blades unlobed, terminal leaflet large, elliptic–ovate, with winding-toothed margins, lateral lobes small; uppermost leaf blades unlobed, lanceolate–elliptic.
- Fruit: Flattish, curved, ridged, light brown, approx. 4 mm long yellowish brown achene.
- Habitat: Arable land, gardens, yards, lawns, dry meadows, roadsides, wasteland, hedgerows, nearby forests, clear-fell areas, shores.
- Flowering time: July–September(–October).
A good identification marker for the Chicory subfamily is the way that its inflorescence is comprised of only tongue-like flowers, and the latex the plants contain on their stem. Nowadays it is questionable if these properties speak of true kinship, or have they been developed many times in the course of evolution. Nipplewort is different from basic Chicory family plants as it does not have much latex and small flowers in small capitula.
Nipplewort is usually an annual and survives by producing seed: one stem yields an average of 500 achenes, and this number can rise to as much as 40,000. The achenes remain in a basket formed by the erect involucral bracts so they can fly out from the mother plant when the rigid stem is shaken by a passing person or animal, or by the wind. The acheness have no flying hairs at all to help them, and although birds like to eat the seeds they probably don’t have much of a role in spreading them. They are carried great distances on the soles of people’s shoes and attached to vehicles.
In the modern culturally-influenced environment there are an abundance of suitable environments for nipplewort, and it is one of the more common weeds on cultivated land. Most Finnish weeds are sensitive to chemical weed-killers, but nipplewort is not much affected by traditional poisons and as it germinates in the autumn it is past the most vulnerable stage when crops are sprayed in the spring. Nipplewort has become more common recently, also ferally in forest margins and on shores, although it never strays far from people and cultivated land. It has not become a weed in the whole country, however: it is apparently native to the south of Finland and cannot stand the prevailing conditions north of central parts of the country.
Although nipplewort is perceived as a weed it also has medicinal properties, having a calming and antiseptic effect, and it also helps staunch the flow of milk when it is time to stop breast-feeding. The medicinal use of the species never spread to Finland from central Europe, however.