A genus of two species formerly included in the Liliaceae, but at present residing in the Agavaceae, where in Hutchinson’s classification Phormium is placed in the monotypic tribe Phormiae. Its proper taxonomic position remains a matter of dispute.
The phormiums are not woody but are so frequently included in nurserymen’s lists of trees and shrubs that perhaps their anomalous inclusion here may be excused.
The phormiums are clump-forming plants, spreading by stout rhizomes. The leaves are evergreen and bear a resemblance in shape and arrangement to those of the flag irises. Flowers bisexual, borne in long-pedunculate inflorescences, the lower part of the peduncle clothed with sterile bracts, the upper bracts subtending flowering laterals. Corolla of six segments, connate at the base. Ovary superior, developing into a loculicidal capsule containing numerous small, winged seeds.
The phormiums were killed or badly damaged in many gardens in the exceptionally severe winter of 1962-3, but should come through most winters unharmed except in the coldest and driest parts of the country. They thrive in a good garden soil, but are not very particular in their requirements, and have been found to succeed well in peaty soil and even in boggy moorland. They are propagated by division.
The phormiums are as out of place among tall shrubs as they are in the herbaceous border. They are best treated as architectural features near buildings, and also look well when rising out of a ground-work of low-growing shrubs and herbaceous plants.