Herbaceous Perennials   Whilst the plants in the foregoing section may be employed almost exclusively as carpeters, a number of the herbaceous perennials are really too tall for this role and, generally speaking, only those with an indicated height of, say, 25cm or under should be considered as suitable. The remainder come into their own either in the purely herbaceous border or, more likely, as valuable fillers between or in front of shrubs in the increasingly more popular and easily managed mixed border. A few, particularly those with swordlike leaves, like the phormiums, irises or yuccas, should stand as specimens with only low carpeters round their feet. IRIS PSEUDACORUS 'VARIEGATA'   To aid viewing the catalogue we have divided up the plants into alphabetical order. Please select a range below to browse the catalogue.