FABACE^E. ' 241 



4. A. aristatus, UHeritier. — Peduncles very short, usually 6-flowered. Teeth of calyx 

 long and setaceous. Leaves with 6 — 9 pairs of linear, oblong, pointed, hairy leaflets. 



A native of mountainous situations in the south of Europe and Greece, and, 

 as above stated, was considered by Sibthorp to be the species known to the an- 

 cients as furnishing gum. Some of the Tragacanth imported from Smyrna 

 and Marseilles is the product of this plant. 



'Dr. Lindley has also described another species, the A. strobiliferus (not of 

 Royle; A. Dicksonii, Royle), from Koordistan, as the origin of the inferior 

 or dark-coloured gum ; but it is evident, from an inspection of the gum of 

 commerce, that all the qualities are collected" at the same time, and that they 

 have a common source, as, whatever may be the port from whence they 

 come, both kinds are mingled together; and it moreover is shown, that this 

 product must be ascribed rather to a sub-genus of Astragalus, than to any 

 particular species. 



Tragacanth, as found in commerce, consists of several varieties, as regards 

 the colour and form of the pieces, though in the same parcel they may all be 

 found. The best is in tortuous, vermicular fragments, often flattened or con- 

 voluted, of a whitish or yellowish- white appearance, and in some cases trans- 

 lucent. The inferior kind is darker coloured, and of a rounded or oblong 

 form more frequently than vermicular. This gum is hard and tough, and is 

 pulverized with much difficulty, except when thoroughly dry and in a heated 

 mortar. Its taste is mucilaginous and mawkish ; it has no odour. When 

 water is added to it, it absorbs a portion of the fluid, swells much, and forms 

 a soft mass, but does not dissolve on the addition of more water. The mix- 

 ture forms a uniform, tenacious paste or mucilage; this, when thin, separates 

 into two portions, the upper consisting of water, with a small quantity of solu- 

 ble gum, and the lower of the Tragacanth, in a pasty form. From different 

 analyses, it is shown to consist of two distinct gums, of dissimilar properties, 

 the one called Adragantin, or the soluble part ; this differs from arabin in 

 several of its characters ; the other termed JBassorin, or the insoluble por- 

 tion ; this merely imbibes water, but does not dissolve in it. 



Medical Properties, SfC. — Tragacanth is merely emollient, demulcent, and 

 nutritive ; but is not as easily digested as some of the other gums. It is em- 

 ployed rather as a vehicle for the administration of other medicines than for 

 its own remedial properties. 



Many other species of this extensive genus have been employed in medi- 

 cine, though none of them are regarded as officinal by our own or the British 

 pharmaceutical authorities. The A. exscapus, a native of the Alps, was 

 brought forward in the latter part of the last century, as a remedy in vene- 

 real affections, especially those of a constitutional character, and where noc- 

 turnal pains existed. From trials made with it, it was found inferior to many 

 other articles, and its use has therefore been abandoned. 



Mucuna. — Adanson. 



Calyx campanulate, bilabiate, the lower lip trifid, the upper entire. Vexillum ascend- 

 ing, shorter than the carina or alae. Carina oblong, straight, acute. Alse oblong, as long 

 as carina. Stamens diadelphous, anthers 20, of which 5 are oblong, linear,, and 5-ovate, 

 hirsute. Legume oblong, 2-valved, with cellular partitions. 



This genus has undergone many changes in its nomenclature, being at 

 one time included in Phaseolus, then in Dolichos ; afterwards separated by 

 Browne, under the name of Stizolobiam, and by Roxburgh, under that of 

 Carpopogon ; whilst at present it is recognised as Macuna, as first instituted 

 by Adanson. The species are twining herbs, with pinnately-ternate leaves 



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