Science

• Dermal tissue

  A young stem consists of an outer protective layer called dermal tissue, composed of the epidermis
• Nodes

  Swollen structures on a stem from which buds, leaves, and branches arise
• Mature woody stem

  Has bark (which replaces the epidermis) with lenticels
• Stele

  The center of the stem
• Vascular tissues

  Function to conduct food, minerals, and water throughout the plant
• Parenchyma

  Composed of parenchyma cells, large, thin-walled, alive at maturity, associated with photosynthesis and nutrient storage
• Pith or medulla

  Composed of soft, spongy parenchyma cells, surrounded by a ring of vascular bundles containing vascular tissues
• Albuminous cells

  In cone-bearing plants, sieve elements are accompanied by albuminous cells
• Stomata

  Pores that allow gas exchange between tissues and the surrounding air
• Sclerenchyma

  Contains sclerenchyma cells, thick secondary walls, die at maturity, provide mechanical support and strengthen the plant
• Meristem

  Tissue containing meristematic cells, undifferentiated cells that give rise to various plant organs and make plants grow
• Stem

  • Usually an erect cylindrical support system of the plant, functions for support and conduction of food, minerals, and water
• Ground tissues

  • Mainly for structural support, fills the spaces between the vascular tissues
• Sclereid

  Irregularly shaped cell providing compression strength but may lessen flexibility
• Cortex

  Lies between the epidermis and vascular bundles, mainly composed of parenchyma cells
• Companion cells

  In seed-bearing plants, sieve elements are accompanied by companion cells
• Bud

  Small growth at the tip or the side of the stem
• Fibers

  Long and narrow cells providing tensile strength without compromising flexibility
• Epidermis

  Protective tissue that covers the entire plant, covered with cuticle and has stomata for gas exchange
• Collenchyma

  Comprised of collenchyma cells, have wall thickenings, alive at maturity, part of vascular bundles, for strengthening and support of the stem