Michelsonia microphylla (kasisi)
Michelsonia microphylla is a rare, although once locally abundant, tropical African forest tree from the Congo basin.
Detail of a line drawing of Michelsonia microphylla taken from 'Legumes of the World' (Illustration: Pat Halliday)
Michelsonia microphylla Hauman
Not formally assessed according to IUCN criteria, but there is concern that the species has become rare.
Primary forest, mainly on hilltops and slopes, at 650–1,200 m above sea level.
About this species
Michelsonia microphylla is a forest tree belonging to the pea and bean family (Leguminosae - or Fabaceae sensu APG (2009)). It is the only species in the genus Michelsonia. Genera comprising a single species are called monospecific.
Geography and distribution
Michelsonia microphylla is limited to the sub-montane area at the eastern rim of the Congo basin in the Democratic Republic of Congo, where it once formed extensive, single species stands. However, it is now considered to be rare.
Michelsonia microphylla forest has been recorded as interdigitating (interlocking like the fingers of two clasped hands) with forest dominated by Gilbertiodendron dewevrei, another leguminous tree species. In the hilly terrain where they grow, trees of M. microphylla occupy the upper slopes and hilltops, whereas trees of G. dewevrei are found on the lower slopes, particularly in the valley bottoms.
A forest tree up to 30 m tall, Michelsonia microphylla has leaves that bear 10–16 pairs of leaflets. The small flowers are arranged in compound inflorescences (flower-bearing structures). Flowers have five white petals, each about half a centimetre long.
The pods (fruits) are woody, flat, broader towards the tip, measure up to about 10 cm long and 7 cm wide and are heavy, sinking in water even when dry. The glossy, brown faces of the pods each have a distinct nerve running lengthways at or just above the midpoint of each face of the pod.
Threats and conservation
Michelsonia microphylla has not been formally assessed according to IUCN Red List criteria.
The distribution described above is based on historical records from collections made almost exclusively in the 1940s and 1950s. During that period there was extensive logging activity in the Congo basin that is thought to have been responsible for a dramatic reduction in the species’ range.
The most recent herbarium collection of Michelsonia microphylla was made in 1972. Attempts to locate individuals in places where they had previously been recorded have so far been unsuccessful.
Reports suggest that historically the timber was considered of good quality and easy to process.
This species at Kew
Pressed and dried specimens of Michelsonia microphylla are held in Kew’s Herbarium where they are available to researchers by appointment.
Angiosperm Phylogeny Group. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III. Botanical Journal of the Linnean Society 161: 105-121.
Lewis, G., Schrire, B., Mackinder, B. & Lock, M. (eds.) (2005). Legumes of the World. Royal Botanic Gardens, Kew.
White, F. (1983). The vegetation of Africa, a descriptive memoir to accompany the UNESCO/AETFAT/UNSO vegetation map of Africa. UNESCO, Natural Resources Research 20: 1-356.
Wieringa, J. J. (1999). Monopetalanthus exit. A systematic study of Aphanocalyx, Bikinia, Icuria, Michelsonia and Tetraberlinia (Leguminosae, Caesalpinoideae). Wageningen Agricultural University Papers 99: 4.
Kew Science Editor: Barbara Mackinder
Copyediting: Emma Tredwell
Kew would like to thank the following contributors: Jan Wieringa, University of the Netherlands
Although every effort has been taken to ensure that the information contained in these pages is reliable and complete, notes on hazards, edibility and suchlike included here are recorded information and do not constitute recommendations. No responsibility will be taken for readers’ own actions.