P. officinarum is a prostrate, monocarpic herb with a rosette of small, setose, oblanceolate, entire leaves and a single terminal shoot apex. Leaves are elliptic, 3-10 cm long, 1-5-2 cm in width, with distinctive white midvein. The lower leaf surface is covered with a dense layer of stellate hairs, and long, simple eglandular hairs cover both upper and lower leaf surfaces and the leaf margin (Sell and West, 1976). P. officinarum has a single flower head per stem. Florets are yellow, often with a red stripe on the outer face, resembling those of dandelions (Taraxacum spp.). Floral evocation results in the development of one or more axillary buds into stolons that bear further apical meristems at their tips and further dormant buds in the axils of their scale-leaves, which can reach a final length of 10-30 cm, occasionally with a terminal capitulum. Under certain conditions, stolon axillary buds may break dormancy and produce branching stolons. Each branch is potentially capable of developing into a new rosette. These daughter rosettes root adventitiously and their stolon connections atrophy. Daughter rosettes may also develop in situ from the axillary buds of the parent rosette. These growth patterns result in mat-forming growth (Bishop and Davy, 1985;Gottschlich, 1996). Since rosettes are monocarpic (semelparous), the parental rosettes will senesce and die (Bishop and Davy, 1985). The fruit is an achene up to 3 mm long, purple-black at maturity, with a pappus.
Related invasive species
- Pilosella officinarum
Related Farm Practice
- Development
- Pastures
P. officinarum is a prostrate herb which has spread rapidly to exotic locations (e.g. New Zealand, North America and South America) after introduction as a garden ornamental or contaminant of agricultural seed. As it continues to be available as an ornamental and can be easily transported by machinery, P. officinarum is likely to spread further. It is an undesirable invader on account of its vigorous growth due to stolon production and wind-dispersed seeds. P. officinarum displaces the inter-tussock vegetation leading to loss of forage and biodiversity.
P. officinarum is generally a pasture or environmental weed, rather than an agricultural weed in crops. However, in North America, P. officinarum is a troublesome weed of fields and pastures (Fernald, 1950;Scoggan, 1979).