98 



DESCRIPTIVE BOTANY 



A. gummifer, Labill. (Gum Tragacanth.) Shrub, 2 feet high. Stems short, 

 naked ; branches numerous and straggling ; bark reddish-gray, slightly rough, 

 marked with scars of fallen leaves ; young twigs woolly. Leaves numerous, 

 spreading in all directions, two and a half inches long, pinnate ; rachis hard, 

 stiff, smooth, yelloAv, acutely pointed, furnished at the base with broad, mem- 

 branous, acute, glabrous, rusty, clasping stipules, cut at the edges ; leatiets op- 

 posite or alternate, nearly sessile, ver}' small, obovate, acute, entire, glabrous, 

 both sides grayish-green, veined, articulated Avith the rachis, soon falling off. 

 Flowers small, sessile, solitary or two to three together in the axils of the loAver 

 leaves, each with a membranous, acute bract as long as the calyx. Calyx cut 

 to the base into 5 equal, very narrow, acute segments, clothed with silky, 

 white hairs, persistent. Petals papilionaceous, a little longer than the calyx, 

 pale yellow, and persistent; wings a little shorter than the standard, witli a 



long linear claw ; keel-petals nearly as 

 long as the wings. Stamens 10, upper 

 one free, 9 united into a sheath, which is 

 attached to the petals at the base. Ovary 

 villous ; style long and filiform ; stigma 

 minute. Pod small and kidney-shaped, 

 smooth, and pale brown. 



This is a very large genus. Most of 

 the woody and spiny species produce the 

 tragacanth gums, but this species is prom- 

 inent among those that produce it, and 

 the first that was accurately described. 

 The species A. tragacantha, from which the 

 gum takes its name, does not yield the 

 drug. 



Geographij. — The Astragalus gummifer 

 and other gum-bearing species are sub- 

 tropical plants, and do not produce the 

 gum unless they grow in a warm climate. 

 The gum which supplies the market is 

 produced in Persia and the region soutli 

 of the Black Sea, Greece and the islands 

 of the eastern Mediterranean, also in 

 Syria. 

 Etiimohgij. — Astragalus, the generic name of this plant, is from the Greek 

 aarpdyaKos, vertebra, an allusion to the crowded and apparently jointed ap- 

 pearance of the beans or seeds in the pods of some of the species of this large 

 genus. Gummifer is from the lj2itva.gummis, gum, and /e?-o, bear, hence gum- 

 bearing, Tragacanth, the name of the gum, is from the Greek rpdyos, a goat, 

 &Kavda, beard, hence a goat's thorn, this name being an allusion to the slender 

 spines with which the branchlets of the A. tragacantha are armed, and which 

 bear a slight resemblance to a goat's beard, which is somewhat like a thorn in 

 shape. 



Histori/. — When or by whom this drug was first used is not known. The 

 ancients were acquainted with it. Theophrastus, who wrote more than three 

 hundred years before the commencement of the Christian era, mentions it. 



Preparation. — The mode of collecting the gum is to remove the earth 

 from the crown of the root, and then make wounds in the bark, from which 

 exudes a whitish gummy sap that hardens in flakes, Avhen it is removed. This 



Astragalus gummifer 

 (Gum Tragacanth), 



