General Info

This deciduous, spineless Tree may reach 30m+.  Watery sap is present.  Simple alternate Leaves have a 3-veined Base.  Small greenish, regular Flowers lack petals and are wind pollinated.  The talked Fruit is a red, fleshy drupe.  Seeds are small.

Description

Celtis mildbraedii, Celtis franksiae, Celtis usambarensis, Celtis soyauxii.

Common names: Natal White Stinkwood, Red-fruited White-stinkwood, Natal Elm.

Family: Cannabaceae (white stinkwood family).  The family includes approximately 11 genera including Cannabis (an erect herb), Humulus (hops: climbing plant).  Genera with trees include Celtis and Trema.  There are about 200 species.  All have Leaves with stipules (basal appendage of the petiole).  Plants are often dioecious (having male and female parts on separate plants). Male inflorescences are larger.  Small Flowers are in cymes, are actinomorphic (regular, symmetrical), have a reduced calyx, lack a corolla and are wind pollinated.  Number of stamens varies.  Two connate carpels are present in the Pistil and here the Ovary is usually superior.  Fruit in an Achene or a Drupe.

Name derivation: Celtis used by Pliny the Elder; (23 AD–79 AD).  It is also Greek name for Laurel tree.  mildbraedii – named after Prof Gottfried Wilhem Johannes Mildbraed (1879-1954), a German botanist and collector who explored extensively in Central and West Africa.  There are 3 indigenous species of the genus Celtis in southern Africa.  The other 2 are C. gomphophylla and C. africana.

Conservation Status: L C. (Least Concern). 2009 (J.E Victor & Raimondo et al.). This was originally considered a rare tree in the RSA but more trees have recently been found.

Tree

This spineless Tree with its spreading Crown and watery sap may reach 30+m high.  Branches tend to droop and start high up the trunk.  Young branches are long and whip-like.  They are usually hairy and may have conspicuous pale Lenticels (a usually raised corky oval or elongated area on the plant that allows the uncontrolled interchange of gases with the environment) present.  The light brown Trunk is smooth with flaking discs.  Buttresses may be present in large trees.

Leaves

This deciduous tree has simple Leaves that are arranged alternatively in 2 opposite vertical rows.  Leaves are elliptic (oval in outline, being narrowed to rounded ends and widest near the middle).  The hairless leaf may reach 17 x 5cm.  Each stiff, shiny green leaf is distinctly 3-veined from the base.  Two of these veins, on either side of the midrib extend about one third up the leaf.  Veins are raised below.  There are 3-6 pairs of lateral veins present.  Net veining is more visible if the leaf is held against a strong light.  The Base is slightly asymmetrical and rounded.  The Apex is pointed.  The Margin may be entire, completely toothed or have the teeth limited to the upper half.  The Petiole (leaf stalk) is up to 9mm long.  Stipules (basal appendages of the petiole) are lanceolate and ephemeral (lasting a short time).  (Aug-Apr).

Flowers

The inconspicuously greenish Flowers have short stalks and are actinomorphic (Regular, symmetrical.  The Perianth – the calyx and corolla are divisible into 3 or more identical sectors or mirror images).  The tree may be monoecious (separate male and female flowers present on the same tree) or bisexual.  Flowers occur on the branches of the current year.  They occur singly or grouped together and are axillary (in the upper angle between a lateral organ, such as a leaf, and the stem that bears it).  In the more numerous Male flowers, the Perianth has 4-5 lobes.  Stamens are incurved only in the bud and there are 4-5 filaments arising from a hairy receptacle (is that expanded tip of the flower stalk from which the floral parts develop).  Anthers are exserted after anthesis (the period or act of expansion in flowers, especially the maturing of the stamens).  The Ovary is inferior or absent.  The Female flower is axillary and rudimentary Staminodes (sterile stamens) are usually present.  There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) and the superior, sessile Ovary has a single locule containing 1 Ovule.  The Style has 2 lobes. (Sep-Oct).

Fruit

The fleshy, hairless, ovoid-ellipsoid Fruit is a small Drupe (a fleshy, 1-seeded indehiscent fruit with the seed enclosed in a stony endocarp; stone fruit e.g. peach).  The ripe, 4-ribbed fruit is distinctively red and up to 10 x 6mm.  It is tipped with the remains of the persistent style (Sep+).  The fruit remains on the tree until after the leaves have fallen.

Distribution & Ecology

Trees are able to grow in low light in coastal and lowland sand forests.  They occur naturally in KwaZulu-Natal e.g. Pigeon Valley (a natural heritage park in Durban with a high level of bio-diversity which was established to provide protection for the about 40 Celtis mildbraediiIt has 110 different species of mainly indigenous trees).  The most southern location of the tree occur in a 20ha Ilanda wilds nature reserve at Amanzimtoti.  These trees also occur in Swaziland, central Mozambique, Zimbabwe (in Chirinda forest – in the Eastern Highlands on the slopes of Mount Selinda) and are widespread through Africa and Madagascar.  Trees may occur in widely scattered coastal and scarp (a steep slope in the land that cuts across the underlying strata) forests up to an altitude of 1 600m.  Birds including hornbills as well as primates eat the Fruit.  Thick-billed weavers fragment the Seeds enabling them to eat the kernels.  The tree is the nesting site for the Black sparrowhawk.

Ethnobotany

The Wood is used for house building and heavy construction.  It is suitable for a slow burning fuel.  The Heartwood is white to pale yellow, has a medium density and works reasonably well in machine tools but is difficult to nail or screw.  The wood should be treated to prevent attacks by blue-stain fungus and borers.  Seeds are small and germination takes up to 4 weeks.  Unfortunately, viable seeds are hard to find.  The Bark has analgesic properties.

References

Boon, R. 2010. Pooley’s Trees of eastern South Africa. Flora and Fauna Publications Trust, Durban.

Burrows, J.E., Burrows, S.M., Lotter, M.C. & Schmidt, E. 2018. Trees and Shrubs Mozambique.  Publishing Print Matters (Pty) Ltd.  Noordhoek, Cape Town.

Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.

Ginn, P.J. McIlleron, W.G. Milstein, S. 1989. The Complete Book of Southern African Birds. Struik Publishers (PTY) LTD. Third impression 1991.

Lawrence, G. H. M, 1951. Taxonomy of Vascular Plants, The Macmillan Company, New York. Tenth Printing 1965.

Palmer, E. & Pitman, N. 1972. Trees of southern Africa, Balkema, Amsterdam, Cape Town.

Alice Notten: thanks for the help with the family name.

 

http://redlist.sanbi.org/species.php?species=3436-6

https://www.facebook.com/FriendsOfPigeonValley?fref=ts

http://prota4u.org/protav8.asp?g=psk&p=Celtis+mildbraedii+Engl.

http://www.biodiversityexplorer.org/plants/cannabaceae/celtis_mildbraedii.htm

http://www.zimbabweflora.co.zw/speciesdata/species.php?species_id=120080

https://en.wikipedia.org/wiki/Celtis_mildbraedii

http://posa.sanbi.org/flora/browse.php?src=SP

https://en.wikipedia.org/wiki/Black_sparrowhawk