Much has been written as to the knowledge of the sex of plants among the ancients. It may be stated that of the sexual elements of the flower no ancient writer had any clear idea. Nevertheless, sex is often attributed to plants, and the simile of the Loves of Plants enters into works of the poets. Plants are frequently described as male and female in ancient biological writings also, and Pliny goes so far as to say that some students considered that all herbs and trees were sexual.[72] Yet when such passages can be tested it will be found that these so-called males and females are usually different species. In a few cases a sterile variety is described as the male and a fertile as the female. In a small residuum of cases diœcious plants or flowers are regarded as male and female, but with no real comprehension of the sexual nature of the flowers. There remain the palms, in which the knowledge of plant sex had advanced a trifle farther. ‘With dates’, says Theophrastus, ‘the males should be brought to the females; for the males make the fruit persist and ripen, and this some call by analogy _to use the wild fig_ (ὀλυνθάζειν).[73] The process is thus: when the male is in flower they at once cut off the spathe with the flower and shake the bloom, with its flower and dust, over the fruit of the female, and, if it is thus treated, it retains the fruit and does not shed it.’[74] The fertilizing character of the spathe of the male date palm was familiar in Babylon from a very early date. It is recorded by Herodotus[75] and is represented by a frequent symbol on the Assyrian monuments. [72] Pliny, _Naturalis historia_, xiii. 4. [73] The curious word ὀλυνθάζειν, here translated _to use the wild fig_, is from ὄλυνθος, a kind of wild fig which seldom ripens. The special meaning here given to the word is explained in another work of Theophrastus, _De causis plantarum_, ii. 9, xv. After describing caprification in figs, he says τὸ δὲ ἐπὶ τῶν φοινίκων συμβαῖνον οὐ ταὐτὸν μέν, ἔχει δέ τινα ὁμοιότητα τούτω δι’ ὁ καλοῦσιν ὀλυνθάζειν αὐτούς. ‘The same thing is not done with dates, but something analogous to it, whence this is called ὀλυνθάζειν’. [74] _Historia plantarum_, ii. 8, iv. [75] Herodotus i. 193.