NEWS from the Dept. Botany and Molecular Evolution 2026

During an afternoon excursion without students, the botanists discovered the boraginaceous plant Trichodesma africanum, which had not been found in the days prior. Trichodesma africanum is widespread in the arid regions of Africa, Arabia, the Near East and India. It is an annual to perennial plant found in deserts, savannahs and dry scrubland. The plant contains pyrrolizidine alkaloids, which are toxic to rodents. Trichodesma africanum is also used in folk medicine and has been found in Egyptian tombs, making it one of the oldest documented medicinal plants. The stem and leaves are covered with spiny, stiff hairs up to 2 mm long with a thickened base, which likely serves as a defence against herbivores.

Fruit of Avicennia marina, one of two mangrove species native to Egypt and belonging to the family Acanthaceae (order Lamiales). The other species is Rhizophora mucronata, which belongs to the family Rhizophoraceae (order Malphigiales). Extreme ecological conditions, such as growth in tidal zones, can lead to morphologically similar adaptations—such as the formation of stilt roots and vivipary—in representatives of very different phylogenetic groups. The latter refers to the germination of seeds and the completion of the early stages of development on the parent plant. The young plants fall to the ground and usually become stuck in the mud near the parent plant. However, they are also buoyant, can drift in the sea for months and establish new mangrove stands. Avicennia marina has a vast distribution range, encompassing the east coast of Africa, south-west, south and south-east Asia, as well as Australia and New Zealand.

The evergreen crucifer Zilla spinosa, a species native to the deserts of North Africa and the Arabian Peninsula, was also widespread in the ‘Haus-Wadi’ visited during the excursion. The thorns are leafless shoots and protect the plant from being grazed. Leaves are only formed in the juvenile stage. This spherical shrub reaches heights of 50 to 200 cm. The plant is extremely drought-resistant and can survive years of drought. If rainfall has been sufficient, the plant flowers mainly in February and March. Under favourable conditions, however, flowers are produced all year round. Zilla spinosa is widely used in folk medicine, particularly for bladder and kidney problems. The phytochemicals exhibit a broad spectrum of biological effects, including antioxidant, antifungal, antifibrotic, hepatoprotective and antiviral effects.

The white zygophyllum (Zygophyllum album), which is just as common as Zilla spinosa, is widespread in often saline arid regions stretching from Spain through North and East Africa to the Arabian Peninsula. In the wadis, it was the most common plant and its stands marked areas where water is available after rainfall. As we discovered for ourselves, the plant is incredibly bitter. This is surely a defence against being eaten. Zygophyllum album is a small, perennial subshrub with opposite, succulent, ovate leaves and small yellowish flowers. The Zygophyllaceae are a diverse group found in arid, saline regions of the tropics and subtropics. In Europe, only a few species occur in the Mediterranean region and the steppe areas south of the Urals.

Descending on a rope to a shipwreck.

Marveling at shipwreck structures heavily colonized by corals (diver with a torch).

The stony coral gardens for which the Red Sea is famous.

Soft corals in a variety of colors.

Thomas Gregor, exhausted after a 10-day field trip—note the literature—he maintains his composure even in his sleep!