Per Ola Karis

Associate Professor, lecturer

Botaniska institutionen
Stockholms universitet
Lilla Frescativägen 5
SE-106 91 Stockholm
Sweden

Phone +46 (0)8 163768
Fax +46 (0)8 165525

My main research interest is the large flowering plant family Asteraceae. I have extensive experience of anatomy and morphology throughout the family owing to painstaking studies of thousands of representative species from all major clades. I also work with molecular techniques. Since a couple of years I have returned to my research "home" South Africa, and I am involved in the joint project "Diversification and evolution in time and space of Asteraceae in arid and semi-arid southern Africa". By using the target clades Arctotideae, Senecioneae-Othonninae, and Calenduleae we aim at elucidating species-level relationships in the arid and semi-arid areas, identify supposed refugia for the Asteraceae (and thus other plant groups) during past climates, model possible range changes under future climates (e.g. global warming). In a recent paper based on morphological data I show that subtribe Gorteriinae (tribe Arctotideae) comprise two sister groups (also supported by recent molecular results by Vicki Funk et al.) in which both arid area and fynbos radiations has taken place. My PhD student, Frida Stångberg, works on the Gorteria clade, where the genus Hirpicium seems to be paraphyletic. Frida will also work on the Metalasia clade, here examplified by Metalasia tricolor on the Rooiberg (Little Karoo), a rare species that was re-discovered some ten years ago by my friend and colleague, the eminent Jan Vlok (of Oudtshoorn).



The Gorteriinae display an extraordinary array of anatomical and morphological features, and one unique character are the longitudinally striate hairs that diagnose the Gorteria clade. There is phylogenetically informative information in the endothecium of the anthers of the Asteraceae, and the Gorteriinae is no exception. Below are SEM pictures of endothecial cells from a sunflower (Helianthus, right) and from a Berkheya (left). Note the striations on the perpendicular ribs in the sunflower. One of my aims is to investigate the endothecia of the Gorteriinae by means of SEM in order to get a clear three-dimensional picture of these diverse cells.



I have also worked on the family Plumbaginaceae, and was involved in an Italian project on the Caryophyllaceae (in particular the genus Moehringia), in which my colleague and friend Simone Fior recently got his PhD at the University of Milan.

Links

The International Compositae Alliance homepage

South African collaborators at Rhodes University, Grahamstown

CapeNature, the Conservation authority of the Western Cape Province

South African National Parks

ALUKA, material about Africa, for example, search images of herbarium sheets of African plants

Publications since 2001