This chapter summarizes studies that were directed toward developing the keys and criteria for identification of plant species and groups in the archaeological remains. It discusses the exomorphic and endomorphic characters of wheat, barley, oats, rice, millets, and pulses. The term ‘seed’ is applied not only to true seeds, but also to equivalent structures which look like and function as seeds. ‘Weed’ is also a relative term, its application being partly dependent on the objectives of the person who uses it. In the chapter, weeds have been referred to as ‘plants whose virtues have not been discovered so far’ and the term is interpreted in a broad sense so as to include any plant found growing wild. The variability in the structure of seeds found throughout the angiosperms and its constancy in narrower groups permit the use of seed characteristics in the identification and classification of taxa.