Nivenia is a genus in the Iridaceae family with 10 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.
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.
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 artifical light the flowering time can be shifted. Photo taken by Martin Grantham in habitat in Kogelberg Biosphere Reserve.
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.
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