PLANTS PRODUCING GUMS AND RESINS 315 



papilionace;e. 



Adesmia balsamica. — In Chili this plant is known as jarilla. It 

 produces a balsamic gum utilized in several local industries. It is 

 a small shrub. 



Astragalus heratensis — According to Watt, a gum called katira or 

 gobina is collected from cracks in the bark of this plant and of other 

 varieties of the same. 



Aitchison remarks that large quantities are gathered near- Bezd, 

 in Khorassan, and are exported to many parts of India, Persia, Turke- 

 stan, &c., where it is employed in making varnishes. The major 

 portion of the gum sold in India under the name of katira comes from 

 this plant. No other Indian plant is responsible for this product. 

 This gum is of a pale colour with irregular grains which somewhat 

 resemble crushed resin. 



Astragalus. — This genus is represented by small perennial shrubs 

 about I metre high. They live on dry and chalky hillocks and are 

 not cultivated. 



Several species produce the gum known as gian tragacanth, which 

 is classed by de Cordemoy as a mixed gum. 



Astragalus Parnassi; A. ce-phaloniciis ; A. strohilifcriis ; A. creticus; 

 A. gummifer; A. cyllcneus; A. verus; A. adscendens; A. micro- 

 ce-phalus; A. -pycnocladiis. 



According to some writers the best gum is derived from A. Parnassi. 



All these plants demand a warm climate and may lose their com- 

 mercial properties when transplanted to another climate. 



The gum arises from the gelification of the cells in the pith 

 of stems and branches and filters through the fissures, solidifying on 

 exposure to the air, m the form of drops. 



The plants are worked by making incisions in the stem after the 

 rainy season. Tw-o kinds of tragacanth are obtained and they are known 

 in commerce as tragacanth in white flakes and tragacanth in yellow 

 flakes. If during the period of drying the weather is fine the white 

 leaves will be obtained, a kind which is very popular; if, on the other 

 hand, the weather is rainy or the breeze strong enough to raise the 

 dust, the gum will be turned yellow and will be only a second quality 

 product. Care should be taken not to tap all the shrubs at once, in 

 order to minimize the risk of a bad season. 



Tragacanth in white flakes is employed in the manufacture of 

 confectionery, in pharmacy, in the wall-paper industry, in the pre- 

 paration of vellum, leathers, and high-class fabrics. 



The following is the composition of gum tragacanth : — 



Water 



Pecti'" compounds 



Soluble yum 



Cellnlo'-e ... 



Starch 



Mineral mat'er 



Nitrogenous bodies 



20 



60 

 8 to 10 



-> 



2 to 3 



3 

 Traces 



