General Info – summary

Tree to 15m high, has watery latex + smooth trunk + corky bark.  Simple, alternate and ovate/triangular Leaves have serrated margins and may be hairy.  Distinctively thin petiole is up to 10cm long.  Unisexual monoecious, and greenish-yellow Flowers are in racemes, with fewer smaller female flowers at the base.  Male has basifixed anthers.  Woody 3-lobed Fruit (a globose capsule) has inedible carunculate seeds.

Description

Croton gratissimus

Previous Names: Croton gubouga, Croton microbotryus.

SA Tree No. 328. Croton gratissimus var gratissimus.  Deep to mid-green leaves.  Upper surface hairless.  Inflorescence 5-15cm long.  This sub. species is much more widespread.  Common names: (Afr) Bergboegoe, Berg-boegoe, Boeghout, Boog, Booghout, Buchu, Kalahariboegoe, Kalahari-boegoe, Koranaboegoe, Korana-boegoe, Laventelbos, Laventelkoorsbessie, Laventel-koorsbessie, Leventelbos, Makwassi, Makwassieboom, Maquassi, Maquassiboom, Maquassie, Maquassieboom, Rekstokbos, Stinkhout, Inkubathi, Korannaboegoe, Laventelkoorsbessie.  (Eng) Lavender croton, Lavender fever berry.  (isiZulu) Ilabele, Inkubathi, Isikhumampuphu, Umahlabakufeni, Umahlabekufeni.  (Northern Sotho) Maloga Mookgwasane, Moologa.  (Southern Sotho) Uhubeshane.  (siSwati) Umwuluka.  (Tshivenḓa) Mufhorola, Muthatha-khubi.

SA Tree No. 328.1. Croton gratissimus var. subgratissimus.  Olive green leaves with stellate hairs on upper surface – (photo 22 under Leaves).  Inflorescence 1-8cm long.  This subsp. is found in Northern South Africa, Zimbabwe, and Botswana.  Common Names: (E) Hairy Lavender Fever-berry. (Afr) Harige Laventel-koorsbessie, Laventel-koorsbessie. (isiZulu) Ilethi, Umahlabekufeni.

Family Euphorbiaceae (Spurge family) e.g., the well-known exotic poinsettia – Euphorbia pulcherrima) with its normally bright red colour due to bracts, not perianth parts (calyx and corolla).  This family has many herbs, and in the tropics, shrubs and trees, including succulents and climbers, are more common.  Apart from Antarctica, members of this family are present in all continents.  Trees are up to 15m high and the trunk may reach 46cm wide.  Spines are paired or absent. Latex/watery sap is present.   Genera on this web site include Croton, Euphorbia and Spirostachys.  Leaves may be largish, absent or reduced, and may fall early.  When present most leaves are simple e.g., Spirostachus.  When compound, the leaves are always palmate (hand-like: compound with leaflets arising from one point).  Leaf shape varies from ovate to lanceolate.  Leaf arrangement is in spirals, opposite or alternate.  Stipules may be spinescent e.g., Euphorbia sp. or may be lost early e.g., Spirostachus.  At the leaf base, the veins are single (midrib) or are 3-5 veined e.g., Macaranga.  Domatia may occur e.g., in Alchornea.  Leaves may smell of almonds if crushed e.g., Croton sp.  When leaves are present the margins are usually irregularly serrated.  Petioles may be swollen at 1 or both ends.  Two glands often occur at each leaf base e.g., Spirostachys.  In some Euphorbiaceae plants, CAM (Crassulacean acid metabolism) photosynthesis can occur.  Here stomata only open at night to reduce water loss.  Inflorescences develop terminally or in leaf axils.  Most flowers are insect pollinated.  Plants may be monoecious (male & female on the same plant) or dioecious (male and female parts on separate plants).  The unisexual Flowers are Actinomorphic (Regular, symmetrical).  They may lack a calyx or a perianth (calyx and corolla).   No members of this family have been proved to be effective against any disease.  Generally, plants in this family contain a large amount Phytotoxins (toxic substances produced by plants).

Name derivation: Croton: resembling ticks – referring to the seeds of some species.  gratissimus means very or most pleasant.  Var. gratissimus has no hairs on upper leaf surface whereas var. subgratissimus has stellate (or radiating) hairs.  William John Burchell first named this plant.  From 1811 – 1815 he travelled with his dog over 7 200km having never spent a night out in the open before!  He collected 40 000 specimens which are now housed at Kew, as are his manuals containing the plant details.  Palmer, E. & Pitman, N. consider this the best journal ever written by early travellers in South Africa.  The Genus Croton has 10+ species in South Africa.

Conservation: National Status: L C. (Least Concern).  Assessed: 2005 (R.H. Archer and J.E. Victor).

Tree

The Tree is neither succulent nor cactus like.  It grows as a shrub or tree up to 15m high and is taller to the north of South Africa.  It is usually a slender tree (photo 493) but may become spreading.  Young branches are brittle, pale white to yellow or light brown (photo 145) and may be covered with cinnamon coloured dots that are glandular scales (photo 255).  The many brittle branches may droop.  The rough and corky Bark is quite pale to dark grey (photo 144).  The bark is fissured near the base (photo 257).  The tree possesses watery Latex.

Leaves

The usually alternate Leaves are simple (have a single blade, which may have incisions that are not deep enough to divide the leaf into leaflets), tend to droop and are pleasantly aromatic when crushed.  They have some striking colours: silvery, gold, mauve and pink.  Some leaves are red and glint in the sun.  Leaves are fragrant when crushed (similar to lavender) due to the presence of aromatic oils.  Leaves are lanceolate to elliptic and variable in size up to 18 x 6cm but usually less than half this size (photo 253).  The leaf is not rough to the touch.  The upper surface is shiny dark green to olive green and may have visible gland dots (photo 22).  When these dots appear in great numbers, the under-surface may appear red-brown.  The impressive lower surface is very pale and silvery and covered with dense, small cinnamon-coloured star-shaped hairs (glandular scales).  The hairs are visible (photo 21).  On this photo, the hairs occur on the Petiole, and Midrib, which protrudes prominently below, and is sunken above (photo 253).  The 8-17 pairs of lateral veins are hardly visible.  They become more visible when viewed against a strong light with the aid of a hand lens (photo 137).  Here the cinnamon coloured dots partly obscure the veins, which turn and join shortly before reaching the margin.  The Apex is tapering to broadly so.  From above, the Base appears to be perched on the petiole (photo 22).  The base is rounded, notched or lobed and has 2 small glands next to the petiole.  The Margin is entire (with a continuous margin, not in any way indented) and may be wavy.  The hairy Petiole (leaf stalk – photo 21) is usually 5 – 70mm long and thin (1mm wide photo 253).  From below, it appears pale yellowish or greenish even red to brown and may be covered with the same cinnamon coloured dots as the leaf blade (photo 21).  Variety gratissimus differs by having no hairs on the upper leaf surface, whereas the upper leaf surface of var. subgratissimus has stellate hairs.  Some red or orange leaves may be present.

Flowers

The cream to reddish brown, sweet smelling, 5-merous Flowers are grouped in branch end Racemes (a simple, unbranched, indeterminate inflorescence with pedicellate – stalked flowers, along the axis that open in succession towards the apex).  Each raceme is from 1 to 15+cm long (photos 196 and 736) and usually has 1-2 female flowers at the base and the rest are males.  In photo 196 strings of flower Buds are covered with dense, small cinnamon-coloured glandular Scales (photo 517) and may remain on the tree for months – usually until after the first rains when they develop into flowers (photo 424).  The 5-lobed Calyx-is partially reflexed (photo 517).  Between calyx lobes, the 5 small, green and hairy Corolla lobes protrude slightly and turn downwards.  These are just visible in photos 515 and 510.

This tree is monoecious (having both male and female reproductive organs on the same plant) but sexes develop in separate flowers.  Male flowers lack an ovary but have many Stamens (photo 436) that are inserted on a usually hairy Receptacle (that expanded tip of the flower stalk from which the floral parts develop).  The receptacle is greatly expanded in the Asteraceae and Ficus).  Filaments are inflexed in the bud (photo 424).  The stamens become erect when the flower opens (photo 510).  The basifixed Anthers appear flattish (photo 515).  The fewer Female flowers located at the base of the raceme are relatively large.  The superior Ovary has 3 Locules (compartments) with a single ovule in each locule.  The 3 Styles are usually bent backwards.  The rest of the flowers on each raceme are male.  Bees are the pollinating agents.  (Aug-Nov).

Fruit

The smallish 3-lobed Fruit is an almost spherical Capsule (a dry fruit resulting from the maturing of a compound ovary, which usually opens at maturity by one or more lines of dehiscence) that is close to 1cm wide (photo 894).  The remains of the perianth parts (photo 894 and 271) and the 3 persistent Stigmas are present.  The fruit is initially green but becomes yellow to brown when mature.  Seeds may have a caruncle (an outgrowth on a seed adjacent to the micropyle).  (Sep-Nov).  In (May-Jun) the dried-out capsule dehisces (opens) – discharging the seeds.

Distribution & Ecology

var. gratissimus commonly occurs on hills that are stony (often quartzite rock composed almost entirely of quartz.  It is non-foliated and usually forms from the metamorphism of sandstone).  This is the dominant tree on the rocky western facing mountain slopes of NW Cape e.g. near the Langeberg.  It is also found in Northern Cape, KwaZulu-Natal, and Gauteng – round Magaliesberg, Limpopo, Mpumalanga, North West and Northern Cape.  Outside South Africa, the plant is located in Swaziland, Mozambique, Namibia and northwards into tropical Africa, including Malawi, Nigeria and Sudan.  The Crested Guineafowl, Emerald-spotted Wood Doves, Tambourine Doves, Terrestrial Bulbuls, Francolins and other birds eat the Fruit.  Butterfly larvae, with large green bodies and horny heads (the Green-veined Charaxes: Charaxes candiope) feed on the Leaves.  This butterfly has the reputation of being very aggressive.  Their larvae also feed on other Croton species.

Ethnobotany

This is a good garden tree that is relatively quick growing.  The Wood is pale, dense, hard, yellow and termite resistant.  It is used for furniture, roofing poles, hut poles and fencing.  The Leaves may be poisonous but are browsed by game and stock.  Bushmen girls use dried, powdered leaves as perfume.  Antioxidants from the plant have been found to have a beneficial effect in the management of cardiovascular, inflammatory, malignant and neurodegenerative (among other) diseases.  The geographic location of the plants seems to profoundly affect the concentrations of active components in the extracts of this plant.  Local medicine makes use of the seeds, bark and leaves.  The bark of Croton gratissimus yielded four cembranolides, including the first reported example of a 2,12-cyclocembranolide.  This compound showed moderate activity against the PEO1 and PEO1TaxR ovarian cancer cell lines.

References

Archer, R.H. & Victor, J.E. 2005. Croton gratissimus Burch. var. gratissimus. National Assessment: Red List of South African Plants version . Accessed on 2024/08/31.

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. and Milstein P. le S, 1989. The Complete Book of Southern African Birds. Struik, Cape Town.

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.

Schmidt, S. Lotter, M. & McCleland, W. 2002. Trees and Shrubs of Mpumalanga and the Kruger National Park. Jacana, Johannesburg.

van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa. Struik, Cape Town.

 

http://www.plantzafrica.com/plantcd/crotongrat.htm

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

file:///C:/Users/Probook/Downloads/molecules-18-01916-v2%20(1).pdf

http://www.sciencedirect.com/science/article/pii/S0031942210002086

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