Most of the cultivated varieties have a long flowering period (and have been considered by botanists as belonging to "Fragaria vesca" var. "vesca" ssp. "semperflorens"). They are usually called "alpine strawberries". They either form runners or multiple crowns in a cluster, fruit over a very long period with larger fruit than the common wood strawberry, and are usually propagated by seeds or division of the plants. The type in cultivation is usually everbearing and produces few runners. Plants tend to lose vigour after a few years due to their abundant fruiting and flowering with final decline caused by viral diseases. Large-fruiting forms are known since the 18th century and were called "Fressant" in France. Some cultivars have fruit that are white or yellow when fully ripe, instead of the normal red.