Thousands of species of succulent plants occur in the dry regions of the world. Succulent plants display an extraordinary array of features to contend with these conditions. Our understanding of these adaptations in the plant kingdom and the evolutionary processes underlying them is patchy. I aim to contribute to a more complete picture of evolution among communities of succulent plants, particularly in Africa.
I work in an interdisciplinary context with a wide network of people. I would be glad to hear from anyone interested in collaborating.
Systematics and evolution of aloes
Aloes are botanical icons of Africa. They are easily recognised and highly appreciated wherever they occur, from the southernmost tip of Africa to the Horn of Africa, the Arabian Peninsula and the islands off the eastern coast of Africa, including Madagascar. There are over 500 species, and the evolutionary relationships and classification of aloes have long challenged botanists.
Our work has shown that the tree aloes (members of the genus Aloidendron, Asphodelaceae subf. Asphodeloideae) are the oldest of the extant aloes. The rambling aloes (Aloiampelos) and fan aloes endemic to the Cape (Kumara) likely evolved before the lineage that gave rise to the aloes in the strict sense – the genus Aloe. New insights into the evolution of aloes have revealed multiple innovations in leaf succulence, pollination syndromes and habitat specialism.
Molecular identification
Succulent plants are immensely popular ornamental houseplants and for water-wise gardens and landscaping. They can, however, be very difficult to identify when not in flower. We are developing DNA-based identification tools to support quality assurance and conservation of succulents in trade.
Evolution of useful traits in succulent plants
Aloe and Euphorbia (Euphorbiaceae) are both examples of large succulent genera in Africa of considerable medicinal value. In Aloe, the leaf exudate and the succulent tissue are used, whereas in Euphorbia, the toxic milky latex is used. We are using the tree of life to prioritise and predict species of interest for a given attribute. Combined with detailed structural investigations of the water-storing tissue, we are building a comparative view of succulence across the plant tree of life.
Olwen M. Grace 