Anatomical adaptations of Boerhavia L. and Commicarpus Standl. (Nyctaginaceae) for survival in arid environments of Namibia
Abstract
Members of the Nyctaginaceae Jussieu. are distributed throughout southern Africa. Eight species of the family occur naturally in arid parts of Namibia. These species have acquired the ability to survive and reproduce in these dry conditions. They are xerophytes, which have been described as drought evaders, avoiders, and drought-tolerant. In the Nyctaginaceae, Boerhavia deserticola, B. hereroensis, Commicarpus helenae and C. squarrosus are thought to be drought avoiders. In this study we investigated their stem, leaf and anthocarp anatomy for adaptations to arid environments. The results indicated that the four species are avoiders, with modifications of the trichomes, secretions, crystals, secondary growth, Kranz esophyll, water storage cells, tannins, mucilage, inner and outer stomatal ledges, large-diameter xylem vessels, and the presence of sclerenchyma in their stems, leaves and anthocarps. These adaptations enable the plants to tolerate arid conditions, conserve water and maintain a high photosynthetic rate, and aid seed dispersal.
occur naturally in arid parts of Namibia. These species have acquired the ability to survive and reproduce in
these dry conditions. They are xerophytes, which have been described as drought evaders, avoiders, and
drought-tolerant. In the Nyctaginaceae, Boerhavia deserticola, B. hereroensis, Commicarpus helenae and
C. squarrosus are thought to be drought avoiders. In this study we investigated their stem, leaf and anthocarp
anatomy for adaptations to arid environments. The results indicated that the four species are avoiders, with
modifications of the trichomes, secretions, crystals, secondary growth, Kranz mesophyll, water storage cells,
tannins, mucilage, inner and outer stomatal ledges, large-diameter xylem vessels, and the presence of sclerenchyma
in their stems, leaves and anthocarps. These adaptations enable the plants to tolerate arid conditions,
conserve water and maintain a high photosynthetic rate, and aid seed dispersal.