3446.000 Acacia Mill. - Thorn trees


VACHELLIA Wight & Arn.

Timberlake, J., Fagg, C. & Barnes, R. (1999) Field Guide to the Acacias of Zimbabwe CBC Publishing, Harare

Description of the genus

Trees or shrubs, sometimes climbing, armed with thorns (native species) or unarmed (introduced species). Leaves alternate, 2-pinnate or (in some introduced spp.) modified to phyllodes and thus appearing to have simple leaves. Pinnae opposite, subopposite, sometimes alternate. Gland usually present on the upper side of the petiole, sometimes also glands on the rhachis. Inflorescences usually axillary, racemose or paniculate; flowers in elongated spikes or spherical heads, bisexual or unisexual. Calyx gamosepalous, subtruncate or with 4-5 lobes. Corolla 4-5(-7)-lobed. Stamens numerous. Anthers glandular or eglandular. Pod very variable, dehiscent or indehiscent. An important genus, occurring commonly in a wide range of habitats. A careful distinction should be made between the stipules which in some species are modified into straight spines arising from near the leaf base and prickles, which are usually curved and are usually found near the nodes but may occur along the stems. Some acacias, especially older trees, may be unarmed, which can be very puzzling. It is recommended that a careful search is made of the tree (if possible) or of similar trees in the area. An important general rule with acacias is that those with straight spines (stipules) have flowers in spherical heads and those with curved prickles have flowers in spikes. The exceptions are: Faidherbia albida has straight spines and flowers in spikes. Acacia mellifera has curved prickles but the flower spike is so short as to appear almost spherical. Acacia schweinfurthii has curved prickles and flowers in spherical heads. Acacia tortilis has both curved prickles and straight spiny stipules and flowers in spherical heads.

Worldwide: 1200 species in tropical and warm areas, many in Australia

Botswana: 42 taxa.

The larvae of the following species of insect eat species of this genus:
Azanus jesous (Topaz-spotted blue)
Cirina forda (Emperor moth)
Cyligramma latona (Cream-striped owl)
Hippotion celerio (Silver-striped hawk, Vine hawk)
Sphingomorpha chlorea (Sundowner moth or Banana hawk)
Acacia hebeclada subsp. hebeclada

Links to taxa:     View: living plant images - herbarium specimen images - all images for this genus

SpeciesFZ divisionsContent
arenaria SchinzN,SEDescription, Image
ataxacantha DC.N,SW,SEDescription, Image
borleae Burtt DavyDescription, Image
burkei Benth.SEDescription
caffra (Thunb.) Willd.SEDescription
davyi N.E. Br.
erioloba E. Mey.N,SW,SEDescription, Image
erubescens Welw. ex Oliv.N,SEDescription, Image
fleckii SchinzN,SW,SEDescription, Image
galpinii Burtt DavyN,SEDescription, Image
gerrardii Benth. var. gerrardii N,SW,SEDescription, Image
grandicornuta GerstnerSEImage
haematoxylon Willd.SW
hebeclada DC.[Agg]N,SW,SE
hebeclada DC. subsp. chobiensis (O. B. Mill.) A. Schreib.[LR-nt]Description, Image
hebeclada DC. subsp. hebeclada Description, Image
hebeclada DC. subsp. tristis A. Schreib.[DD]
hereroensis Engl.SEDescription, Image
karroo HayneN,SEDescription, Image
kirkii Oliv. subsp. kirkii var. kirkii NImage
luederitzii Engl. var. luederitzii N,SW,SEDescription, Image
luederitzii Engl. var. retinens (Sim) J.H. Ross & Brenan
mellifera (Vahl) Benth. subsp. detinens (Burch.) BrenanN,SW,SEDescription, Image
nebrownii Burtt DavyN,SWDescription, Image
nigrescens Oliv.N,SEDescription, Image
nilotica (L.) Willd. ex Delile subsp. kraussiana (Vatke) BrenanN,SEDescription, Image
permixta Burtt Davy
polyacantha Willd. subsp. campylacantha (Hochst. ex A. Rich.) BrenanNDescription, Image
rehmanniana SchinzNDescription, Image
robusta Burch. subsp. clavigera (E. Mey.) BrenanNDescription, Image
robusta Burch. subsp. robusta N,SEDescription
schweinfurthii Brenan & ExellN,SEDescription, Image
senegal (L.) Willd. var. leiorhachis BrenanDescription, Image
senegal (L.) Willd. var. rostrata BrenanN,SEDescription, Image
senegal (L.) Willd.[Agg]N,SE
sieberiana DC. var. woodii (Burtt Davy) Keay & BrenanNDescription, Image
stuhlmannii Taub.SEDescription, Image
swazica Burtt DavyImage
tenuispina I. Verd.SE
tortilis (Forssk.) Hayne subsp. heteracantha (Burch.) BrenanN,SEDescription, Image
tortilis (Forssk.) Hayne subsp. spirocarpa (Hochst. ex A. Rich.) BrenanNDescription
xanthophloea Benth.SEDescription, Image

Other sources of information about Acacia:

Our websites:

Flora of Caprivi: Acacia
Flora of Caprivi: cultivated Acacia
Flora of Malawi: Acacia
Flora of Malawi: cultivated Acacia
Flora of Mozambique: Acacia
Flora of Mozambique: cultivated Acacia
Flora of Zambia: Acacia
Flora of Zimbabwe: Acacia
Flora of Zimbabwe: cultivated Acacia

External websites:

African Plants: A Photo Guide (Senckenberg): Acacia
BHL (Biodiversity Heritage Library): Acacia
EOL (Encyclopedia of Life): Acacia
GBIF (Global Biodiversity Information Facility): Acacia
Google: Web - Images - Scholar
iNaturalist: Acacia
IPNI (International Plant Names Index): Acacia
JSTOR Plant Science: Acacia
Mansfeld World Database of Agricultural and Horticultural Crops: Acacia
Plants of the World Online: Acacia
Tropicos: Acacia
Wikipedia: Acacia

Copyright: Mark Hyde, Bart Wursten, Petra Ballings and Meg Coates Palgrave, 2014-24

Hyde, M.A., Wursten, B.T., Ballings, P. & Coates Palgrave, M. (2024). Flora of Botswana: Genus page: Acacia.
https://www.botswanaflora.com/speciesdata/genus.php?genus_id=667, retrieved 24 April 2024

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