Studies in the southern African species of Justicia and Siphonoglossa (Acanthaceae): seeds

The seeds of all species of Justicia (except J. thymifolia (Nees) C.B. Cl.) and Siphonoglossa in the southern African region (as defined by the Flora of southern Africa) were examined with the Scanning Electron Microscope. A wide range of different seed surfaces were seen, many of which could be correlated with other characters to further reinforce grouping of species into sections. However, some species that on other characters, would be placed together, had widely differing seed testas. Gross surface morphology varied from smooth to colliculate, irregularly rugose, reticulate with the ridges variously arranged, wheel-shaped (radiate or ammonite-like), with a central ridge or with multicellular barbed scales. The seeds were without hairs, unlike some American species sometimes considered to belong in Justicia (Graham 1989). Micromorphology also provided useful characters, with seeds being reticulate, papillate, minutely or deeply rugose or with one to many crystals visible. Critical-point drying was sometimes helpful in viewing microstructure.