Pilosella Pilosellina group
- Family: Daisy Family – Compositae, subfamily Cichorioideae (formerly Chicory Family – Cichoriaceae)
- Growing form: Perennial herb. Often with runners, sometimes with short runners–runnerless.
- Height: 5–25(–40) cm (2–10(–15 in.). Stem unbranched, hairy, sparsely leaved–leafless, scape-like.
- Flower: Single flower-like capitula usually 1.5–2 (0.6–0.8 in.) cm broad, surrounded by involucral bracts. Capitulum flowers pale–dark yellow (outer bracts often red-streaked underneath), tongue-like, tip 5-toothed. Stamens 5. Gynoecium composed of 2 fused carpels. Involucral bracts in many rows, tapered–quite tapered, varyingly with star, unbranched and glandular hairs. Solitary capitulum terminating scape.
- Leaves: In basal rosette and sometimes alternate on stem, almost stalkless. Blade elliptic–lanceolate–narrowly obovate, with entire margins, (sometimes small-toothed), top straight-haired (straight hairs sometimes absent), densely stellate-haired underneath and sometimes on top.
- Fruit: Round, grooved, 1.5–2.5 mm (0.06–0.1 in.) long achene crowned with yellowish brown unbranched hairs.
- Habitat: Dry meadows, meadow river-banks, roadsides, banks, yards, rocky outcrops, sandy meadows, light-filled slopes.
- Flowering time: June–July.
Hawkweeds are one of Finland’s most diverse plant groups. Their seed subject matures into a seed without receiving pollen from another plant, which means that descendants are clones of the mother plant. The smallest hereditary deviations thus constitute permanent new forms. Thousands of these kinds of micro-species have already been described. Genus Pilosella was originally separated from the hawkweed group because its members form a clear genus of plants with scapes and leaf rosettes which reproduce sexually.
Genus Pilosella is often further divided into two groups: mouse-ear hawkweeds (Pilosellina) have only one capitulum while genus Cauligera have many. The genus can also be divided into around 20 large species, of which a dozen grow wild in Finland. Within these large species there is much diversity, and some of these even cross-breed with other large species.
Mouse-ear hawkweeds in Finland are all grouped into the subspecies Pilosella officinarum, or alternatively these forms can be regarded as independent species (e.g. shaggy mouse-ear hawkweed, P. peleteriana or P. officinarum ssp. peleteriana and mouse-ear hawkweeds, P. officinarum or P. officinarum ssp. pilosella). It is good to remember, however, that these divisions are completely artificial: mouse-ear hawkweed is not a species in the way that we usually think of a plant or animal but rather a highly diverse species group comprised of about 150 micro-species. The differences between them are often extremely small and only identifiable by experts, so it is more sensible for the majority of amateur and professional botanists to divide mouse-ear hawkweeds into larger units. Broadly-defined mouse-ear hawkweed is easily identifiable.
Mouse-ear hawkweed grows in dry, sunny places such as rocky and sandy fields, and it also thrives in old cultural environments. It can’t stand shade at all and needs a lot of light. In suitable habitats it spreads widely, forming patches of dense, mat-like stands which often attract attention from a distance with their silver-grey leaves and lively yellow capitula.