A beautiful evergreen bearing masses of pure white flowers with yellow stamens in March-April.  Height 3-4m.  Plant in sun or partial shade. Avalanche has the largest flowers and the widest foliage of any x cartmanii variety and is quite happy trailing along the ground or spilling over a wall. Pruning is not necessary and flowering occurs on 1 year old wood so if you feel a need to prune, do this immediately after spring flowering. Raised by Robin White and registered in 1996, it is a cross between 2 New Zealand Clematis, C. mamoraria and C. paniculata. Crosses between these two parents are known as x cartmanii.