Abstract

The pollen morphology of 63 African Impatiens species (Balsaminaceae) is studied using scanning electron microscopy. In addition, the pollen wall structure of five African Impatiens species was investigated with transmission electron microscopy. Pollen of African balsams is medium to large in size. Oblate Impatiens pollen is most common yet peroblate and suboblate pollen are also well represented. African pollen of the genus Impatiens is mainly circular, rectangular or elliptic. Reticulate sexine ornamentation is characteristic for most of the species investigated. Both homobrochate and heterobrochate pollen is present within the genus. Occasionally, the lumina are not entirely demarcated by muri, resulting in coalescence between adjacent lumina. The muri vary from slender with a tapering top edge, to slender with a rounded edge, to broad, more or less flattened muri. The tectal muri are always supported by two or three rows of short and massive columellae. Orbicules are absent in all species investigated. Observations of the pollen wall stratification show that pollen of African Impatiens consists of a thin foot layer, a lamellated endexine (characterized by remnants of the white lines) and a one-layered intine. Foot layer and endexine are slightly intermingled and therefore sometimes difficult to distinguish from each other.

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