Botanical soil determination Pointer or indicator plants of wild flora are of the greatest practical importance for agricultural and horticultural work. They characterise their location almost infallibly and provide information on the reaction state of the soil, its structure, especially the proportion of fine soil and the state of cooking, the nutrient content, the water and heat supply, the development potential of the soil and its suitability for certain types of crops and forms of cultivation. The Boas , a richly illustrated and excellently edited work from 1958, is still a much sought-after, but hardly available classic on this subject.