Geigeria

Geigeria is a genus of flowering plants in the family Asteraceae, native to southern Africa. The genus is characterized by its often aromatic foliage and the presence of toxic compounds, making some species a concern for livestock poisoning, particularly in arid and semi-arid grazing lands.

Description:

Geigeria species are typically perennial herbs or subshrubs, although some may be annuals. They vary in size and growth habit. The leaves are often alternate, simple, and can be linear, lanceolate, or ovate, depending on the species. The flowers are arranged in solitary or corymbose heads (capitula), typical of the Asteraceae family. The ray florets are usually yellow, while the disc florets are also yellow or sometimes brownish. The fruit is a cypsela, a dry, single-seeded fruit.

Toxicity:

Several Geigeria species are known to contain sesquiterpene lactones, which are toxic to livestock, particularly sheep and cattle. These toxins can cause a variety of symptoms, including vomiting, diarrhea, weakness, and even death. The specific toxins and their concentrations vary between species and even within species depending on environmental factors. The condition caused by Geigeria poisoning is often referred to as "vomiting disease" or "geigeriosis."

Distribution and Habitat:

Geigeria species are primarily found in southern Africa, including countries like South Africa, Namibia, Botswana, and Zimbabwe. They typically inhabit dry, open areas such as grasslands, savannas, and rocky outcrops. They are often associated with disturbed or overgrazed land.

Ecological Significance:

While Geigeria can be problematic due to its toxicity, it also plays a role in the ecosystem. It provides food and shelter for various insects and other animals. Its presence can also be an indicator of land degradation and overgrazing.

Taxonomy:

The taxonomy of Geigeria has been subject to revision over time. The genus belongs to the tribe Anthemideae within the Asteraceae family. The exact number of species is debated, with estimates ranging from 20 to 30 recognized species.

Uses:

Despite their toxicity, some Geigeria species have been traditionally used in folk medicine for various ailments. However, due to the potential for poisoning, caution is advised when considering any medicinal use. Research is ongoing to investigate the potential pharmaceutical properties of compounds found in Geigeria, but these are still in the early stages.