This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
A genus of plants confined to New Zealand and Norfolk Island. Though not quite hardy in any part of England, we give it a place here because it is extensively used and well adapted as a large pot-plant for decorating terraces, flights of steps, or planting out in clumps. Only two, or at the most three species are known, differing chiefly in size and colour of the flowers. They are tall rigid herbs with fleshy fibrous roots. Leaves radical, linear-ensiform, distichous, coriaceous, and very tough. Flower-scapes variable in height from 5 to 15 feet, branched and bracteate. Flowers large, dull red or yellow; perianth tubular, curved, the inner segments with spreading tips. The name is from the Greek a basket, in allusion to the application of the leaves. The best known species is P. tenax, New Zealand Flax, a plant with very thick coriaceous narrow leaves from 3 to 6 feet long, dark green above, paler below, always split at the tip. Flowers numerous, in panicles, yellow or red. P. Cookianum is distinguished from the foregoing by its smaller stature, greenish-yellow flowers, and especially by its more acuminate leaves, which are rarely split at the apex.