Mimosa coronillæfolia.—Pers. Encheirid. n. 44.
Sassa gummifera.—Gmel Syst. ex DC. 1. c.
Of this plant very little indeed is known, and we were unfortunately unable to find either flower or fruit of the only Acacia which we met with on our visit to Marocco, and which we were assured was the Gum Arabic plant (Alk Tlah) of that country. It is interesting as representing the northern limit of distribution of the immense genus Acacia in Africa. Our specimens, such as they are, coincide perfectly with the description of Acacia gummifera in Willdenow, and with the excellent figure in Hayne, which was taken from specimens collected by Broussonet near Mogador. We found the plant abundantly in the lower region of Southern and Western Marocco, occurring as a thorny bush, along with Rhus pentaphylla and other shrubs. That it was the plant producing the Marocco Gum Arabic the natives consistently testified, though this could not be inferred from the description in Jackson’s ‘Account of the Empire of Marocco’ p. 136, who says of the gum that it ‘is produced from a high thorny tree called Attalet, having leaves similar to the Arar, or gum Sandarac tree, and the Juniper.’ Jackson goes on to say:—
‘The best kind of Barbary gum is procured from the trees of Marocco, Ras-el-wed, in the province of Abda; the secondary qualities are the produce of Shedma, Duquella, and other provinces; the tree grows abundantly in the Atlas mountains, and is found also in Bled-el-jerrêde. The gum, when new, emits a faint smell, and, when stowed in the warehouse, it is heard to crack spontaneously for several weeks; and this cracking is the surest criterion of new gum, as it never does so when old; there is, however, scarcely any difference in the quality. The Attaleh is not so large a tree as the Arar, which produces the Sandarac gum, nor does it reach the size of the Auwar tree, which produces the gum Senegal. It has a low crooked stem, and its branches, from the narrowness of its leaves (long and scanty), have a harsh, withered, and unhealthy appearance at the time it yields the most gum—that is, during the hot and parching months of July and August; but although not an ornamental tree, it is a most useful plant, and will always be considered valuable. Its wood is hard, and takes a good polish; its seeds, which are enclosed in a pericarpium, resemble those of the Lupin, yield a reddish dye, and are used by the tanners in the preparation of leather. These seeds attract goats, who are very fond of eating them. The more sickly the tree appears, the more gum it yields; and the hotter the weather, the more prolific it is. A wet winter and a cool or mild summer are unfavourable to the production of gum.’
As observed in the body of this work, the gum does not seem to be collected in the western portion of its range in South Marocco, but in Demnet, whence it is brought to Mogador; and it may very well be that it is only in the hotter and drier regions of the interior that the gum is produced in sufficient quantities to be worth collecting.
It is remarkable that no notice whatever of Acacia gummifera occurs in Flückiger and Hanbury’s invaluable ‘Pharmacographia’ (1874), where the Marocco gum is supposed to be the produce of Acacia arabica Willd., a plant which extends from Nubia to Natal, and eastward to Central India, but which is not known as a native of Marocco. In another passage of the above work (p. 211), the ‘Marocco, Mogador, or brown Barbary gum,’ is described as consisting ‘of tears of moderate size, often vermiform, and of a rather uniform light dusky brown tint. The tears, which are internally glassy, become cracked on the surface and brittle if kept in a warm room; they are perfectly soluble in water.’
It is possible that the Acacia arabica, which is found in Senegal, may extend to the Sous Valley, and be the source of some of the Marocco gum; and that more than one species producing gum are confounded together by the Moors; this is the natural inference from Jackson’s account, itself anything but explicit. On the other hand, I am informed in a letter lately received from Mr. R. Drummond Hay, H.B.M. Consul at Mogador, who has kindly had inquiries made for me, that the Acacia arabica (Alk Awarwhal) is not found in Sous, no tree of the kind existing either north or south of the Atlas, but that its gum is brought from Soodan by Arabs, and is of inferior quality to that of the Acacia gummifera. Mr. Hay further informs me that the Acacia gummifera grows chiefly in the provinces of Blad Hamar, Rahamma, and Sous.
As stated above, the specimens which we collected of Acacia gummifera precisely accord with the published description and drawing; but we have others under this name from Mr. Cosson’s collector, Ibrahim, gathered near Mogador and at Ouanyna, which differ in having very short spines, ⅙ to ¼ in. long, whilst those of our plant are from ⅔ to ¾ in. long and much stouter.
Very small plants of Acacia gummifera are living at Kew, raised from seeds obligingly presented by Mr. Cosson. They grow exceedingly slowly, and several have been lost by damping off. They are not in a state fit for exhibition.