Calligonum L.
Genus composed of more than 140 species, mostly typical of the Asian deserts, 4 reach North Africa, where they settle in different habitats in dunes and interdune depressions of the Sahara.
Key to species
1 Fruits with few hairs, therefore their surface can be clearly seen, ending in a terminal tuft Calligonum calvescens
1 Fruits so densely covered in hairs that their surface cannot be seen, giving it the appearance of a woolly sphere, ovoid, 15-20 mm in diameter 2
2 Fruit cross section in a cross, in which each end has 2rows of hairs. Shrub 1-2 m in height, highly branched, without a main trunkand young branches grey Calligonum polygonoides
2 Shrub 2-3 m, with branches arising from a trunk sometimes partially buried in the sand. Old branches with whitish, fissured bark. Perianth parts with a green thickening on the dorsal side, yellowish anthers. Fruit hairs long, 8-10 mm, fused at the base into a membrane 3
3 Shrub 2-3 m, with branches arising from a trunk sometimes partially buried in the sand. Old branches with whitish, fissured bark. Perianth parts with a green thickening on the dorsal side, yellowish anthers. Fruit hairs long, 8-10 mm, fused at the base in Calligonum azel
3 Trees up to 10 m in height. Old branches with yellow-orange bark, slightly or not fissured. Perianth parts with a reddish thickening on the dorsal side, white anthers. Fruit hairs very long, 15-20 mm, free to the base Calligonum arich
Bannour, M., Lachenmeier, D.W., Straub, I. et al. 2016. Evaluation of Calligonum azel Maire, a North African desert plant, for its nutritional potential as a sustainable food and feed. Food Research International 1(558-564).
Dhief, A., Gorai, M., Aschi-Smiti, S. and Neffati, M. 2009. Comparative phenological and water potential patterns of three Calligonum species in the eastern Great Erg of Tunisia. Flora-Morphology, Distribution, Functional Ecology of Plants 204(8): 581-592.
Dhief, A.,Abdellaoui, R., Tarhouni, M., Belgacem, A. O., Smiti, S. A. and Neffati, M. 2011. Root and aboveground growth of rhizotron-grown seedlings of three Tunisian desert Calligonum species under water deficit. Can. J. Soil Sci. 91(15-27).
Gouja, H., Garnatje, T., Hidalgo, O., Neffati, M., Raies, A. & Garcia, S. 2014. Physical mapping of ribosomal DNA and genome size in diploid and polyploid North African Calligonum species (Polygonaceae). Plant Syst Evol.
Key to species
1 Fruits with few hairs, therefore their surface can be clearly seen, ending in a terminal tuft Calligonum calvescens
1 Fruits so densely covered in hairs that their surface cannot be seen, giving it the appearance of a woolly sphere, ovoid, 15-20 mm in diameter 2
2 Fruit cross section in a cross, in which each end has 2rows of hairs. Shrub 1-2 m in height, highly branched, without a main trunkand young branches grey Calligonum polygonoides
2 Shrub 2-3 m, with branches arising from a trunk sometimes partially buried in the sand. Old branches with whitish, fissured bark. Perianth parts with a green thickening on the dorsal side, yellowish anthers. Fruit hairs long, 8-10 mm, fused at the base into a membrane 3
3 Shrub 2-3 m, with branches arising from a trunk sometimes partially buried in the sand. Old branches with whitish, fissured bark. Perianth parts with a green thickening on the dorsal side, yellowish anthers. Fruit hairs long, 8-10 mm, fused at the base in Calligonum azel
3 Trees up to 10 m in height. Old branches with yellow-orange bark, slightly or not fissured. Perianth parts with a reddish thickening on the dorsal side, white anthers. Fruit hairs very long, 15-20 mm, free to the base Calligonum arich
Updated by: F. Alcaraz.