Economic botany is the study of the relationship between people (individuals and cultures) and plants. Economic botany intersects many fields including established disciplines such as agronomy, anthropology, archaeology, chemistry, economics, ethnobotany, ethnology, forestry, genetic resources, geography, geology, horticulture, medicine, microbiology, nutrition, pharmacognosy, and pharmacology. This link between botany and anthropology explores the ways humans use plants for food, medicines, and commerce. History In a 1958 essay at the conference that founded the Society for Economic Botany, David J. Rogers wrote, "A current viewpoint is that economic botany should concern itself with basic botanical, phytochemical and ethnological studies of plants known to be useful or those which may have potential uses so far underdeveloped. Economic botany is, then, a composite of those sciences working specifically with plants of importance to [people]." Closely allied with economic botany is ethnobotany, which emphasizes plants in the context of anthropology. Botany itself came about through medicine and the development of herbal remedies. Thus at its advent, botany was economic as well as systematic. As plants became useful for herbals and curatives, their economic value increased. An early set of instructions drawn up by a cosmographer of Charles the fifth instructed explorers to "determine what are the items of sustenance of the land and which ones are generally used, whether fruits or seeds, and all manner of spices, drugs, or whatever other scents, and find out the time in which one can reproduce the trees, plants, herbs, and fruits that these parts offer, and if the natives use them for medicines, as we do." Teosinte and rice are two examples of plants modified so that their economic values would increase. Economic Botany in Colonial Spain Contrary to common belief that modern economic botany had been spearheaded by the British as early as the 19th century, economic botany had been exemplified in the form of plant diffusion for millennia. It really took a foothold beginning as early as the 7th century during the early phases of the Islamic Empire. Then it was further studied by the Spanish due to their lack of economic power in the spice trade of colonial world. Roots in Islamic Endeavors As the Islamic Empire reached its westernmost limits on the Iberian Peninsula, Muslims were able to bring with them flora from the east. Between the 10th and 11th centuries, multiple types of non-native citrus were reported to exist on the Iberian Peninsula.