Examples cited refute a generally accepted view that the origins of metaphors are arbitrary. To illustrate this point, examples are cited of how products of nature (curcubitic plants: melons, pumpkins) are used as references to people and their characteristics (hardiness, appearance, texture, inertness, reproductive and sexual connotations). In various contexts these comparisons express similarity and differences, two principles upon which metaphors typically develop. The frequent occurrences of plant metaphors suggest that nature, or reinforcement through nature, has played the larger role in the metaphors' survival. Accordingly, curcubitic symbolism has tended not to exist or to survive in parts of the world in which the plants do not occur. Thus the capability of users of the symbol to grasp its meaning depends on both the tradition of the sign and the user's knowledge of curcubitic plants. (MSE)