Boron is a subgroup III metalloid. Boron atoms exist in three valency states and have a strong affinity for oxygen. Unlike other micronutrients, essentiality of boron is confined to vascular plants. Boron (boric acid) in plants has the property to form complexes with hydroxyl radicals of compounds having two closely situated -OH groups in cis-configuration. Important among these compounds are the o-diphenols and sugars (Loomis and Durst, 1991). Strong boron-diol complexes are formed between boric acid and ds-diol furanoid groups of sugars such as apiose and fucose. This property of boron forms the basis for a structural and functional role of boron in plant cell walls and plasma membranes.