Description:

• Evergreen shrubs or subshrubs, sometimes forming cushion-like tufts, with a woody underground caudex and woody aerial stems
• Stems few to many, upright or inclined, compressed, becoming rounded below, brittle and woody (with secondary growth), marked with leaf scars, main axes simple, branched or bearing short-lived spur shoots
• Leaves sword-shaped, crowded apically, distichous
• Inflorescence usually compound, composed of paired (binate) rhipidial units, these 2- or 1-flowered; synflorescence either in racemose or corymbose arrangement, occasionally inflorescence a single binate rhipidium; spathes coriaceous to more or less dry, lanceolate to ovate-truncate, long or short; floral bracts usually longer than spathes, occasionally shorter, membranous to scarious, brown or silvery, smooth or wrinkled
• Flowers actinomorphic, sessile, hypocrateriform, shades of blue, often pale in tube, some species heterostylous, plants then either with long style (pin) and short stamens, or long stamens and short styles (thrum), unscented, containing small amounts of nectar from septal nectaries; perianth tube well developed, cylindric, short to long
• Tepals subequal, lanceolate to ovate, spreading or shallowly cupped
• Stamens: filaments short and barely exserted from tube (pin flowers) or well exserted, in 1 species unequal, 1 shorter than others, included in tube (in thrum flowers); anthers oblong, submedianly fixed, sometimes blue; pollen monosulcate, exine reticulate
• Ovary globose; locules usually 2-ovulate, up to 6-ovulate in 1 species
• Style filiform, reaching to just below mouth of tube (thrum flowers) or well exserted, dividing into filiform, recurved branches or shortly 3-notched
• Capsules fusiform, more or less woody
• Seeds tangentially compressed and shield shaped, 1, occasionally 2, per locule, up to 6 in one species, rugose, surface colliculate, testa often partly exfoliated
• x = 16

Classification Notes:

• The genus is closely related to the other shrubby Cape genera, Klattia and Witsenia, which have the same basic chromosome number, growth form, capsule morphology, and similar seed morphology and development
• Leaf anatomical characteristics, secondary growth in the caudex and specialised endothecial thickenings are shared with the Australasian Patersonia (Manning & Goldblatt 1990; Goldblatt 1993)

Nomenclature:

• Nivenia Vent.
  • Ventenat: 5 (1808)
  • Weimarck: 356 (1940)
  • Goldblatt: 51 (1993)

Distribution & Notes:

• Southern Africa: Species 10, Western Cape, from near sea level to 1500 m, on rocky sandstone soils in fynbos, riverine scrub or forest margins

Additional Notes:

• The flowers of Nivenia are adapted for pollination by large-bodied, long-tongued bees, mostly Anthophoridae or long-proboscid flies (Prosoeca: Nemestrinidae; Goldblatt & Bernhardt 1990)
• Six species display morphological heterostyly