Plant Tissues: Ground
Ground Tissues consist primarily of thin-walled parenchyma cells. Other ground tissue is composed of collenchyma cells and sclerenchyma cells
- most common type of plant cell
- large vacuoles, thin walls, and are initially(briefly) more or less spherical
- living protoplasts push up against each other shortly after being produced and produce other shapes, ending up with 11 to 17 sides.
- function in storage of food and water, photosynthesis, and secretion
- most abundant cells of primary tissue and may also occur in a much lesser extent insecondary tissues.
- most only have primary walls(walls laid down while the cells are still maturing)
- less specialized than other plant cells, although many variations occur with special functions ( nectar and resin secretion or storage of latex, proteins, and metabolic waste).
- functional nuclei and are capable of dividing
- remain alive after maturation; (100 years old in cacti)
- some contain chloroplasts (especially in leaves and other outer plant parts)- photosynthetic parenchyma tissue called chlorenchyma
- have living protoplasts and may live for many years
- usually a little longer than wide
- have walls that vary in thickness
- provide support for plant organs, allowing them to bend without breaking(flexible)
- often form strands or continuous cylinders beneath the epidermis of stems or stalks and along the veins in leaves.
- provide much support for stems in primary plant body.
- example: celery strings.
- tough, thick walls.
- usually lack living protoplasts at maturity (unlike collenchyma and parenchyma)
- secondary cell walls impregnated with lignin
- lignin -highly branched polymer that makes cell walls more rigid. cell walls containing this are considered lignified. Common in walls of plant cells that have a structural or mechanical function. Could be in primary walls as well.
- two types: fibers and sclereids; both serve to strengthen the tissues in which they occur
- fibers - long, slender cells that are usually grouped together in strands.
- sclereids- variable in shape but often branched.May occur singly or in groups; they are not elongated, but may have many different forms (one is a star). Found in hard seed coats. Cause gritty texture of pair.
BIOL 1105/1106 Virginia Polytechnic Institute and State University