Sap by the fact that phloem sap is physiologically extreme in terms of animal digestion, and it is hypothesized that few animals take direct advantage of this because they lack two adaptations that are necessary to enable direct use by animals. These include the existence of a very high ratio of non-essential/essential amino acids in phloem sap for which these adapted Hemiptera insects contain symbiotic microorganisms which can then provide them with essential amino acids; and also insect "tolerance of the very high sugar content and osmotic pressure of phloem sap is promoted by their possession in the gut of sucrase-transglucosidase
Tissue (biology) layer of cells) or stratified (multiple layers of cells). However, other cellular features, such as cilia may also be described in the classification system. Some common kinds of epithelium are listed below: In plant anatomy, tissues are categorized broadly into three tissue systems: the epidermis, the ground tissue, and the vascular tissue. Plant tissues can also be divided differently into two types: Meristematic tissue consists of actively dividing cells, and leads to increase in length and thickness of the plant. The primary growth of a plant occurs only in certain, specific regions, such as in the tips of stems or