See Chaenomeles speciosa (Sweet) Nak. var. japonica.  ‘Rubra’ is a cultivar with red flowers.  How it differs from the variety figured under Chaenomeles speciosa japonica is unclear and that illustration is also used here.  ‘Rubra grandiflora’, of low and spreading habit with large, crimson flowers, is an old variety raised in Belgium.  [Hilliers'].