Shrimp Plant Systematics

An Academy botanist travels to Madagascar to fill in missing branches on the shrimp plant family tree.

Burdened by increasing population pressures, the people of Madagascar are rapidly turning the island's forests into rice fields. In the second half of the 20th century alone, half of the country's remaining forests disappeared. Unfortunately, these lands are home to an amazing number of endemic species - plants and animals that cannot be found anywhere else on Earth. Among them are plants like the Madagascar periwinkle, which is now the drug of choice for childhood leukemia. Many other endemic plants and animals in Madagascar have yet to be discovered and described. Academy botanist Tom Daniel is working to fill in some of these blanks by studying the island's shrimp plants (Acanthaceae family), which get their name from the reddish, shrimp-shaped flower clusters that some species bear.

Daniel recently returned from a month long expedition to Madagascar, where he collected about a hundred different shrimp plants - some of which may prove to be new species once he examines them thoroughly at the Academy. So far, scientists have documented about 400 shrimp plant species in Madagascar, of which over 80% are endemic to the island. These numbers make Madagascar one of the centers of evolution and endemism for the shrimp plant family. Daniel is hoping to work out some of the evolutionary pathways and migration patterns of these plants by studying their DNA. For each plant he collected, Daniel stored a few young green leaves in a pouch of silica sand, which preserves the tissue for later DNA analysis. Some shrimp plant genera are present only on Madagascar and in the West Indies - one of the biogeographic puzzles Daniel hopes to address with his current research.

Madagascar periwinkle (Catharanthus roseus) is an endemic plant that is used to treat childhood leukemia.
Photo: Tom Daniel, CAS.
An endemic shrimp plant, Barleria her, in southern Madagascar. Photo: Tom Daniel, CAS.
Tom Daniel cultivating shrimp plants from Madagascar at the Conservatory in Golden Gate Park. Photo: Lihua Zhou, CAS.