Plants Plants Tools A B parenchyma tissue is composed of thin-walled cells found in leaves, stems, and roots sclerenchyma cells have tough, thick cells that strengthen and support plant tissues xylem conducts water sieve tube elements phloem cells arranged end to end; conducts a variety of plant products companion cells keep their nuclei and other organelles throughout their lifetime root tissues epidermis, cortex, and vascular root hairs absorb dissolved nutrients from soil spaces through the process of active transport Casparian strip prevent water molecules from seeping back between cells root pressure part of the driving force behind the movement of water from roots to leaves cortex transports water and nutrients inward through the root and may sotre sugars or starches parenchyma distributed throughout the stem and is often used for storage bark formed by phloem tissue vascular cambium makes more xylem and phloemcells, enabling the stem to grow thicker dormancy a plant's growth slows or stops rhizomes thick, fleshy, creeping stems that grow either along or just beneath the surface of the ground tubers modified underground stems that are swollen with stored food, usually in the form of starch bulbs tulips and daffodils blades collect sunlight cuticle waterproof waxy coating stomata small openings found in plant cells that control the loss of water