birdseye pearlwort, common pearlwort, prostrate pearlwort
Sagina procumbens L.
Perennial Broad-leaved Weeds
Procumbent pearlwort is a matted native perennial frequent on paths, ditch sides, in lawns and occasionally in short turf in pasture throughout the UK. It occurs occasionally as a summer or winter annual. It is locally common in gardens and arable fields on bare soil and open vegetation particularly where moisture is present for long periods. Procumbent pearlwort is resistant to treading and colonises the cracks between paving slabs. It is also found growing on the soil in potted and container grown plants. It is recorded up to 3,780 ft in Britain.
Procumbent pearlwort is both phenotypically plastic and genotypically variable.
Procumbent pearlwort flowers from May to September. The flowers self-pollinate automatically. Seed is set from June to October. Each seed capsule contains 60 to 80 fine seeds.
In laboratory studies under low and high light intensity and in darkness, germination was complete in the light but just 1% of seeds germinated in the dark. Seedling emergence in field plots cultivated at monthly, 3 monthly or yearly intervals or not at all, extended throughout the year. The majority of seedlings emerged in two peaks, one in March-April and the other October-December. The greatest number of seedlings emerged in the uncultivated plots and the least in those cultivated monthly.
Procumbent pearlwort seedlings are frost tolerant.
Persistence and Spread
Procumbent pearlwort can develop a large seedbank. Seed may persist for more than 8 years in the soil beneath a stable habitat such as a lawn or pasture even when not represented in the vegetation.
The small seeds are wind dispersed. Seed has been found in horse droppings. The prostrate shoots root and produce laterals.
Shoots that become detached can form new plants.
Procumbent pearlwort is low growing and is susceptible to competition from taller plants. It can develop an ascending habit in taller vegetation. Procumbent pearlwort is unlikely to be troublesome on arable land and normal tillage operations should keep it in check.
In grassland grazed by horses, procumbent pearlwort is often found growing in latrine areas.
Updated November 2007.