6. A. pycnocladus Boiss. et Haussk., nearly related to A. microcephalus; it was discovered on the high mountains of Avroman and Shahu in Persia by Professor Haussknecht, who states that it exudes tragacanth in abundance.
7. A. stromatodes Bunge, growing at an elevation of 5,000 feet on the Akker Dagh range, near Marash in Northern Syria.
8. A. kurdicus Boiss., a shrub 3 to 4 feet high, native of the mountains of Cilicia and Cappadocia, extending thence to Kurdistan. Haussknecht has informed us that from this and the last named species, the so-called Aintab Tragacanth is chiefly obtained.
Probably the drug is also to some extent collected from
9. A. verus Olivier, in North-western Persia and Asia Minor.
Lastly as to Greece, tragacanth is also afforded by
10. A. Parnassi Boiss., var. cyllenea, a small shrub found in abundance on the northern mountains of the Morea, which is stated by Heldreich[705] to be the almost exclusive source of the tragacanth collected about Vostizza and Patras.
History—Tragacanth has been known from a very early period. Theophrastus in the 3rd century b.c. mentioned Crete, the Peloponnesus and Media as its native countries. Dioscorides, who as a native of South-eastern Asia Minor was probably familiar with the plant, describes it correctly as a low spiny bush. The drug is mentioned by the Greek physicians Oribasius, Aëtius, and Paulus Ægineta (4th to 7th cent.), and by many of the Arabian writers on medicine. The abbreviated form of its name “Dragantum” already occurs in the book “Artis veterinariæ, seu mulomedicinæ” of Vegetius Renatus, who lived about a.d. 400. During the middle ages the gum was imported into Europe through the trading cities of Italy, as shown in the statutes of Pisa,[706] a.d. 1305, where it is mentioned as liable to impost.
Pierre Belon, the celebrated French naturalist and traveller, saw and described, about 1550, the collecting of tragacanth in the northern part of Asia Minor; and Tournefort in 1700 observed on Mount Ida in Candia the singular manner in which the gum is exuded from the living plant.[707]
Secretion—It has been shown by H. von Mohl[708] and by Wigand[709] that tragacanth is produced by metamorphosis of the cell membrane, and that it is not simply the dried juice of the plant.