ACANTHACEAE Juss.
Family composed of about 242 genera and about 3,950 herbaceous or shrubby species, rarely trees, distributed mainly in tropical and subtropical regions. In North Africa it is represented by 8 genera, 4 of which comprise herbaceous species (Acanthus, Blepharis, Dicliptera and Justice). Avicennia have 1 shrub or tree species of more than 3 m in height, typical of coastal mangroves. A further 3 genera (Ecbolium, Ruellia and Barleria) comprise shrubs and subshrubs, with E. viride, the largest species, reaching 2 m in height. The other 5 woody species of this family found in North Africa do not exceed 50-60 cm in height.
R. patula Jacq., is a subshrub with opposite, ovate and petiolate leaves, with flowers practically solitary, white or pale blue-violet, with corolla tube infundibuliform in the upper half and 5 ± equal lobes, and androecium didynamous, with included stamens. Relatively common in sub-Saharan Africa and S of the Arabian Peninsula, it is found in the SE of Egypt and in the northern half of Mauritania.
To the genus Barleria belong the other 4 species, with ± bilabiate corolla and androecium with 2 exserted stamens attached to the upper lip. B. schmittii Benoist is a densely branched subshrub, with leaves with a spiny margin and linear-lanceolate bracts with a spine up to 3 cm, and blue-violet flowers; it is endemic to the western Sahara and N of Mauritania. The remaining North African species of the genus are unarmed: B. acanthoides Vahl (Ara. Egypt: Kwataag), has a corolla tube much longer than the lobes (10 times), typical of the desert areas of the S Sahara; in North Africa it is found in the Tibesti Massif (S of Libya) and the mountain ranges of Jebel Elba and surrounding areas (SE of Egypt). B. lancifolia T.Anderson is characterised by lanceolate leaves and pinkish flowers with a corolla tube ± the same length of the lobes, typical of tropical and steppic areas of Africa; it is found in the N of Mauritania and probably in SW Morocco. B. hochstetteri Nees (Ara. Egypt: Alimaseib) has ovate leaves and whitish or pinkish flowers, with a corolla tube ± the same length of the lobes, distributed in eastern Africa and S of the Arabian Peninsula; in North Africa it is found in the SE of Egypt, in the Jebel Elba and nearby mountain ranges.
Currently, they have not been assessed at a global level in the IUCN Red List of Threatened Species. In the Red List of vascular plants of Egypt (Flora Aegyptiaca Vol 1, 2000) R. patula is listed as “Rare” and B. acanthoides as “Vulnerable”.
Key to genera
1 Trees or shrubs 3-11 m in height, in marshy coastal areas, with respiratory roots. Corolla actinomorphic, with 4 lobes and short tube Avicennia
1 Subshrubs or shrubs up to 2 m in height, in dry areas, without respiratory roots. Corolla zygomorphic, with 4-5 lobes and long tube 2
2 Corolla ± actinomorphic, with 5 patent lobes ± equal in size and shape. Androecium with 4 stamens included in corolla tube Ruellia
2 Corolla bilabiate, with lower lip with 3-4 lobes and upper lip with a single lobe. Androecium with 2 exserted stamens 3
3 Corolla bluish-green, with narrow tube, curved, lower lip trilobed with ovate or oblong lobes and upper lip linear, bifid Ecbolium
3 Corolla pinkish or mauve-pinkish, with wide tube, straight, lower lip with 4 lobes and upper lip with lobe of the same width or wider than the lower lip Barleria
Updated by: B. Valdés & J. Charco.