Flora Unveiled

From Empedocles to Theophrastus j 223

223 223

during his discussions of fruit shedding and the phenomenon of “degeneration” in

fruit trees.

Theophrastus on the Causes of Fruit Shedding in Figs

Theophrastus had noted that the premature shedding of fruit in fruit tree orchards was a

chronic problem for farmers. He assumed that the causes of premature shedding were the

same in all fruit trees. In fact, there are several potential causes of premature fruit drop. One

type may occur when the fruits are still small. This type of fruit drop is thought to be caused

by competition among the fruits, resulting in self- thinning. A second type of fruit drop is

triggered by adverse external factors, such as disease, pests, temperature, and water stress.

A third cause is lack of pollination.

Fruit drop in cultivated figs is typically caused by the absence of wasp- mediated pollina-

tion. Caprification— the practice of tying branches of caprifig syconia to the intact branches

of the edible fig female trees— prevents this type of fruit drop by supplying pollen- bearing

fig wasps to the immature syconia of the female tree. However, Theophrastus adhered

closely to Aristotelian doctrine by concluding that the beneficial effect of caprification

was an asexual process. Having ruled out sexuality, he felt obliged to provide an alternative

physiological explanation, the so- called “open fig theory.”

In Theophrastus’s view, the critical step in the caprification process occurs when the “gall-

insects” (fig wasps), which “are engendered from the seeds” of the caprifig, emerge and “eat

the tops of the cultivated figs.” By so doing, the wasp stimulates the growth of the syconium:

This is the reason for the process called ‘caprification’; gall insects come out of the

wild figs which are hanging there, eat the tops of the cultivated figs and so make them

swell.^41

According to the “open fig theory,” fig wasps stimulate the “swelling” of the cultivated fig

syconia in two ways: (1) by creating a hole in the fig that allows accumulated vapors to escape

and (2) by consuming the “excess fluid” in the fruit. Based on the humors theory, cold, damp

things grow slowly, while hot, dry things grow rapidly. The cultivated fruit’s internal cool

moisture prevents it from actively growing, so it is shed from the tree. The gall insect pre-

vents this by gnawing holes in the syconium and consuming the liquid, enabling it to dry.

Theophrastus on Artificial Pollination in Date Palms

Theophrastus thought he had succeeded in explaining the role of the wasp in caprification

by the open fig theory. The historian Herodotus, whose work Theophrastus knew well, mis-

takenly believed that the method of fruit production in cultivated date palm trees was the

same as that for the fig in every respect, including the participation of a “gall- fly”:

Palm- trees grow [in Babylonia] in great numbers over the whole of the flat country,

mostly of the kind which bears fruit, and this fruit supplies them with bread, wine,

and honey. They are cultivated like the fig- tree in all respects, among others in this.

The natives tie the fruit of the male- palms, as they are called by the Greeks, to the