This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
This well-known fleshy-rooted African plant is almost hardy, and is usually grown in tubs in any garden soil out-of - doors during the summer, and protected in greenhouses or sheds during the winter. It has long leathery strap-shaped leaves and large umbels of bright-blue flowers during the summer and autumn. There are many varieties, such as albidus, white; Leichtlini, deep blue; maximus, large, blue; flore pleno, double; minor and Mooreanus, both small and compact; bi-color, blue and white; Weillighi, lavender; and argenteus, with silvery-striped leaves.