Common Sorghum—Holcus sorghum, Linnæus; Andropogon sorghum, Brotero; Sorghum vulgare, Persoon.
Botanists are not agreed as to the distinction of several of the species of sorghum, and even as to the genera into which this group of the Graminæ should be divided. A good monograph on the sorghums is needed, as in the case of the panicums. In the mean time I will give some information on the principal species, because of their immense importance as food for man, rearing of poultry, and as fodder for cattle.
We may take as a typical species the sorghum cultivated in Europe, as it is figured by Host in his Graminœ Austriacœ (iv. pi. 2). It is one of the plants most commonly cultivated by the modern Egyptians, under the name of dourra, and also in equatorial Africa, India, and China.[1933] It is so productive in hot countries that it is a staple food of immense populations in the old world.
Linnæus and all authors, even our contemporaries, say that it is of Indian origin; but in the first edition of Roxburgh’s flora, published in 1820, this botanist, who should have been consulted, asserts that he had only seen it cultivated. He makes the same remark for the allied forms (bicolor, saccharatus, etc.), which are often regarded as mere varieties. Aitchison also had only seen the sorghum cultivated. The absence of a Sanskrit name also renders the Indian origin very doubtful. Bretschneider, on the other hand, says the sorghum is indigenous in China, although he says that ancient Chinese authors have not spoken of it. It is true that he quotes a name, common at Pekin, kao-liang (tall millet), which also applies to Holcus saccharatus, and to which it is better suited.
The sorghum has not been found among the remains of the lake-dwellings of Switzerland and Italy. The Greeks never spoke of it. Pliny’s phrase[1934] about a milium introduced into Italy from India in his time has been supposed to refer to the sorghum; but it was a taller plant, perhaps Holcus saccharatus. The sorghum has not been found in a natural state in the tombs of ancient Egypt. Dr. Hannerd thought he recognized it in some crushed seeds brought by Rosellini from Thebes;[1935] but Mr. Birch, the keeper of Egyptian antiquities in the British Museum, has more recently declared that the species has not been found in the ancient tombs.[1936] Pickering says he recognized its leaves mixed with those of the papyrus. He says he also saw paintings of it; and Leipsius has copies of drawings which he, as well as Unger and Wilkinson, takes to be the dourra of modern cultivation.[1937] The height and the form of the ear are undoubtedly those of the sorghum. It is possible that this species is the dochan, once mentioned in the Old Testament[1938] as a cereal from which bread was made; yet the modern Arabic word dokhn refers to the sweet sorghum.
Common names tell us nothing, either from their lack of meaning, or because in many cases the same name has been applied to the different kinds of panicum and sorghum. I can find none which is certain in the ancient languages of India or Western Asia, which argues an introduction of but few centuries before the Christian era.
No botanist mentions the dourra as wild in Egypt or in Arabia. An analogous form is wild in equatorial Africa, but R. Brown has not been able to identify it,[1939] and the flora of tropical Africa in course of publication at Kew has not yet reached the order Graminæ. There remains, therefore, the single assertion of Dr. Bretschneider, that the tall sorghum is indigenous in China. If it is really the species in question, it spread westward very late. But it was known to the ancient Egyptians, and how could they have received it from China while it remained unknown to the intermediate peoples? It is easier to understand that it is indigenous in tropical Africa, and was introduced into Egypt in prehistoric time, afterwards into India, and finally into China, where its cultivation does not seem to be very ancient, for the first work which mentions it belongs to the fourth century of our era.
In support of the theory of African origin, I may quote the observation of Schmidt,[1940] that the species abounds in the island of San Antonio, in the Cape Verde group, in rocky places. He believes it to be “completely naturalized,” which perhaps conceals a true origin.
Sweet Sorghum—Holcus saccharatus, Linnæus; Andropogon saccharatus, Roxburgh; Sorghum saccharatum, Persoon.
This species, taller than the common sorghum and with a loose panicle,[1941] is cultivated in tropical countries for the seed—which, however, is not so good as that of the common sorghum—and in less hot countries as fodder, or even for the sugar which the stem contains in considerable quantities. The Chinese extract a spirit from it, but not sugar.