When forms and physiological conditions pass from one into another, and are distinguished by characters which vary according to circumstances, we are led to consider the individuals as constituting a single species, although these forms and conditions possess a certain degree of heredity, and date perhaps from very early times. We are, however, forced to consider them separately in our researches into their origin. I shall first indicate in what country each variety has been discovered in a wild or half-wild state. I shall then speak of cultivation, and we shall see how far geographical and historical facts confirm the opinion of the unity of species.
The _common annual flax_ has not yet been discovered, with absolute certainty, in a wild state. I possess several specimens of it from India, and Planchon saw others in the herbarium at Kew; but Anglo-Indian botanists do not admit that the plant is indigenous in British India. The recent flora of Sir Joseph Hooker speaks of it as a species cultivated principally for the oil extracted from the seeds; and Mr. C. B. Clarke, formerly director of the botanical gardens in Calcutta, writes to me that the specimens must have been cultivated, its cultivation being very common in winter in the north of India. Boissier[583] mentions _L. humile_, with narrow leaves, which Kotschy gathered “near Schiraz in Persia, at the foot of the mountain called Sabst Buchom.” This is, perhaps, a spot far removed from cultivation; but I cannot give satisfactory information on this head. Hohenacker found _L. usitatissimum_ “half wild” in the province of _Talysch_, to the south of the Caucasus, towards the Caspian Sea.[584] Steven is more positive with regard to Southern Russia.[585] According to him, it “is found pretty often on the barren hills to the south of the Crimea, between Jalta and Nikita; and Nordmann found it on the eastern coast of the Black Sea.” Advancing westward in Southern Russia, or in the region of the Mediterranean, the species is but rarely mentioned, and only as escaped from cultivation, or half wild. In spite of doubts and of the scanty data which we possess, I think it very possible that the annual flax, in one or other of these two forms, may be wild in the district between the south of Persia and the Crimea, at least in a few localities.