The stout, spiny Trees are usually up to 10m high and, initially, have a papery pealing bark. Leaves are imparipinnate. The small, yellowish Flowers are regular. Fruit is a small, fleshy drupe. Seeds have a red pseudo-aril.
RSA Tree No. – not indigenous in RSA.
Common names: River Commiphora, River Corkwood.
Family: Burseraceae (The torchwood family, which include frankincense from Boswellia sacra, myrrh from Commiphora myrrha both of which have an incense like odour). Non-allergenic resin occurs in in most plant tissues. Worldwide there are about 16 genera and in excess of 500 species, which occur in tropical South America, Malasia and Africa. In the RSA Commiphora is the only genus and there are about 20 species that may be regarded as trees. The Bark is smooth, aromatic and pealing or flaking. The Leaves are resinous and usually without stipules. The usually dioecious Flowers have 4 or 5 petals and sepals that are imbricate (having regularly arranged, overlapping edges, as roof tiles). Flowers are actinomorphic (regular, symmetric) and have Stamens that have double or equal the number of petals. The superior Ovary has 3-5 carpels with 2 ovules in each and the single Style ends in a capitate (forms like a head) or lobed Stigma. The pitted Fruit is often an edible drupe.
Name derivation: Commiphora – Greek: kommi – gum and phora – bearer. ugogensis – of Ugogo in Tanzania where the type specimen was found.
Conservation Status: unknown. Consumption of the trees by elephants is a cause for concern in some areas.
Description. This Tree is usually up to 10m high and the stem is usually fairly straight. It has many branches that are spreading and angular. The Trunk is irregular and knobbly, and up to 40cm wide. Young branches are initially pubescent and distinctly zigzag. The outer Bark is initially papery and peals into small flakes. It becomes pinkish to rusty brown with time. The pealing reveals a green under-bark. Resin ducts are present in the bark. Unlike many local species, there are impressive stout, single Spines on small branches. These are straight and up to 4cm long. The small branches are covered with small hairs.
This deciduous tree has Leaves that are imparipinnate (compound leaf ending in a single leaflet). There are 6-10 pairs of Leaflets present and the leaf ends in a single one. The 5-10 paired lateral leaflets increase in size towards the leaf Apex. The terminal single leaflet is up to 7,5 x 2,3cm. The leaflet Apex is rounded, broadly tapering to acuminate (said of an acute apex whose sides are somewhat concave and taper to a protracted point). The Base may be asymmetrical and rounded. Margins are finely serrated. Individual Hairy leaflets are ovate to narrowly oblong and have prominent Veins. These veins are much more distinct on the lower surface. The Petiole (leaf stalk) is up to 2,5cm long and is hairy.
The yellowish, small Flowers are sessile. They occur in dense clusters on dwarf spur branches. Flowers are actinomorphic (regular, symmetrical. The Perianth, the calyx and corolla, are divisible into 3 or more identical sectors). The pubescent, very short Sepals have a base that is joined. The externally densely pubescent Petals alternate with sepals and are up to 5mm long. A cylindrical Disc (a more or less fleshy or elevated development of the receptacle) is present. The stamens have filaments that are in 2 different lengths. There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) containing a 2-locular, superior Ovary. (Oct-Dec).
The small, fleshy Fruit is an almost spherical drupe (a fleshy, 1-seeded indehiscent fruit with the seed enclosed in a stony endocarp; stone fruit e.g. peach) which is up to 2cm in diameter. A 4-lobed, bright red, Arillode / false aril / pseudo aril (a structure in certain seeds that resembles an aril but is developed from the micropyle of the ovule as opposed to the stalk) with a wavy margin covers more than half the seed. The arillode has 2 long, corrugated arms and 2 short, triangular arms. (Jan-Apr).
Distribution & Ecology
These plants are Located in Northern Zimbabwe along alluvial areas and rivers in the Zambezi valley. Trees also occur in Tanzania, Mozambique and Zambia. This tree may form thickets. It is commonly found on alluvial soils, along rivers and with an annual rainfall between 800-1 400mm.
Fruit is edible.
Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.
Lawrence, G. H. M, 1951. Taxonomy of Vascular Plants, The Macmillan Company, New York. Tenth Printing 1965.
van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa, Struik, Cape Town.