Lappula is a genus of annual herbaceous flowering plants in the borage family, Boraginaceae (order Boraginales). Commonly called stickseeds, these plants are named for their distinctive fruits — small, prickly nutlets armed with hooked or barbed bristles that readily attach to animal fur and clothing, an effective mechanism for seed dispersal. The flowers are typically small and funnel-shaped, often blue or white, resembling those of other borage-family members such as forget-me-nots (Myosotis). Approximately 80 species are accepted in the genus, distributed across temperate and subtropical regions of the world, including North America, Eurasia, North Africa, South Africa, and southern South America. The genus is best known in a weedy context: Lappula squarrosa, the European stickseed, is regarded as a noxious invasive weed across much of North America and other regions outside its native Eurasian range.
Etymology
The name Lappula is a Latin diminutive of lappa (a bur), referring to the small, bur-like nutlets covered in hooked bristles that characterize the genus and give rise to the common name "stickseeds."
Distribution
Lappula species are native to temperate and subtropical regions worldwide, with the greatest diversity in Eurasia. The range extends to North America, North Africa, South Africa, and southern South America. Several species, most notably Lappula squarrosa, have spread well beyond their native Eurasian range and are established as weeds in North America and elsewhere.
Ecology
Lappula species are annual herbs typical of disturbed habitats, roadsides, dry grasslands, and steppe-like environments. Their barbed nutlets are adapted for epizoochory — dispersal by adhering to the fur of passing animals or the clothing of people — which has facilitated their spread as weeds across new regions.
