Abstract
Ph.D.
Cussonia Thunb. is a genus of 21 species (including one that is
currently undescribed) found in grasslands, woodlands and forests of sub-
Saharan Africa, the Arabian Peninsula (Yemen) and the Comoro Islands. The
genus generally has soft brittle branches, a fleshy underground tuber and
fleshy roots. Despite these features, Cussonia is not found in the dry and arid
regions of Africa. They are generally trees or shrubs, and less often lianes (C.
thyrsiflora Thunb.) or suffrutices (C. corbisieri De Wild.). The tree forms
usually grow between 4 to 20 m in height; however C. zimmermannii Harms
can grow up to 45 m tall. Cussonia corbisieri has a large woody underground
caudex with multiple 1 m tall, herbaceous stems. Probably the most
distinguishing feature of this genus is the shape and size of the leaves. The
palmately compound leaves are carried (in most cases) on the ends of the
branches. The simple palmatisect leaves, such as in C. arborea Hochst. ex
A.Rich. or C. natalensis Sond., are not subdivided into smaller leaflets, while
the compound leaves increase in complexity from mono-palmately compound
to multi-palmately compound. The multi-palmate compound leaves are
carried on long petioles (up to 700 mm) having up to nine leaflets (up to 500
mm long), with each leaflet having two or more articulations bearing
secondary leaflets (up to 400 mm long). These secondary leaflets can be
subdivided into tertiary leaflets (up to 200 mm long).