Nivenia is a genus in the Iridaceae family with 11 species. It is a genus in a group referred to as South African woody irids. This fascinating and little studied group of plants that also includes the genus Witsenia with one species and Klattia with three species can grow to be true shrubs producing thickened woody stems that arise from woody caudices. The largest species and the one with the longest cultivation history, Nivenia corymbosa, can exceed nine feet in height with a woody base more than a foot and a half across! All have leaves in two ranks making stiff fans of foliage along flattened stems. They may not qualify as geophytes, but are certainly related as monocots with a caudex.
Seeds are said to germinate better when treated with smoke water. For more information, consult Martin Grantham's excellent article on how to grow woody irids.
Nivenia binata blooms in the spring with flowers that range from pale blue to dark blue and up to a little over 3/4 in. across. The branching pattern of the inflorescence brings the flowers nearly into a single plane. It is a heterostylous species. It grows in the Swartberg Mountains over a range of conditions. Photo by Andrew Harvie taken in habitat at Seweweekspoort.
Nivenia stokoei has the largest flowers of the genus up to 1.5 in. across that vary from pale silvery blue to deep blue. The foliage is quite waxy glaucous. It grows in a limited coastal area in and around the Kogelberg Biosphere Reserve. When grown under artificial light the flowering time can be shifted. Photo #1 was taken by Martin Grantham in habitat in Kogelberg Biosphere Reserve. Photos 2-4 were taken by Nhu Nguyen and photo 5 was contributed by the UC Botanical Garden.
Information furnished by Martin Grantham in his Introduction to Woody Irids when it was the topic of the week on the Pacific Bulb Society list in July of 2003.