Description:

• Deciduous perennials
• Rootstock a corm, globose to ovoid and asymmetric or campanulate, usually with a basal ridge from which roots emerge, basal in origin, tunics woody, or rarely membranous to fibrous, concentric or imbricate, then notched below
• Stem aerial, simple or branched, terete in section, sometimes puberulous or scabrid, drooping in bud
• Leaves few to several, lower 2 or 3 cataphylls; foliage leaves 2 to several, unifacial, usually with a definite midrib, blades plane to terete or H-shaped in section, sometimes margins and/or midrib raised and winged, sometimes hairy or sticky
• Inflorescence a spike, rarely flowers solitary on branches, flowers usually spirally arranged; bracts green and soft-textured to membranous, inner smaller than outer and notched apically
• Flowers actinomorphic or zygomorphic, rotate to hypocrateriform, variously coloured, often shades of blue to violet, also pink, yellow, cream, purple, red or bicoloured, unscented, sometimes with nectar from septal nectaries; perianth tube short to long, funnel-shaped or cylindric
• Tepals subequal, inner usually shorter than outer, cupped or spreading from base
• Stamens symmetrically disposed or unilateral and declinate; filaments filiform, sometimes of unequal length, one shorter than other two, arising at mouth of tube or well inside tube; anthers erect or ascending, rarely included; pollen monosulcate, operculate, exine perforate
• Style filiform, central, eccentric or unilateral and held below stamens, usually exserted, branches usually slender and recurved, or broadly expanded above
• Capsules globose to oblong or cylindric, membranous to cartilaginous
• Seeds angular to globose, flattened at chalazal end, smooth or rugulose, matte, surface colliculate or areolate
• x = 13

Classification Notes:

• Geissorhiza and the allied Hesperantha are distinguished in Ixioideae by their unusual woody corm tunics, and corms with a basal ridge from which the roots arise
• They also share the unusual base number
• Geissorhiza is the less specialised of the two and difficult to define except in relation to Hesperantha
• There are two subgenera, Weihea with concentric, and Geissorhiza with derived, imbricate corm tunics
• Adaptive radiation in Geissorhiza is extensive with species adapted to a variety of habitats and pollinators

Nomenclature:

• Geissorhiza Ker Gawl.
  • Ker Gawler: 223 (1804)
  • Goldblatt: 302 (1985)
• Sphaerospora Klatt
  • Klatt: 725 (1863) name illegitimate not of Sweet ex Loudon (1841)
• Engysiphon G.J.Lewis
  • Lewis: 19 (1941)

Distribution & Notes:

• Southern Africa: Species 84, Namaqualand and western Karoo (Northern Cape) to Eastern Cape, mostly Western Cape
  • Notable are a number of species that occur only on cliffs close to or under waterfalls
  • The phytogeography corresponds closely to the classic model for members of the Cape flora

Additional Notes:

• The majority of species are more or less generalists pollinated by various bees and hopliine beetles but those with pale pink, long-tubed flowers are pollinated by long-proboscid flies (Tabanidae and Nemestrinidae)