Plant Tissues: Overview Meristematic and Permanent Tissues

Meristematic tissues – localized regions of cell division Apical Meristems Apical Meristems Primary or Transitional Meristem  Primary growth Primary or Transitional Meristem  Primary growth Lateral Meristems Lateral Meristems Vascular cambium  2 o vascular tissue Vascular cambium  2 o vascular tissue Cork cambium or phellogen  periderm Cork cambium or phellogen  periderm Intercalary Meristems (found in the nodes of grasses) Intercalary Meristems (found in the nodes of grasses)

Root and Apical Meristem

Root Apical Meristem 1.Root cap initials 2.Protoderm 3.Ground meristem 4.Procambium 5.Root cap

Lateral Meristems – secondary growth in woody plants This stem has two lateral meristems. They are the vascular cambium and the cork cambium. (This is 1 year)

Lateral Meristem- 2 years This is the 2 nd year and you can see there are two layers of xylem for each year. The pith is also referred to as the “Heartwood” This is the 2 nd year and you can see there are two layers of xylem for each year. The pith is also referred to as the “Heartwood”

Stems-Internal Monocot : examples: corn, grasses Monocot : examples: corn, grasses Dicot: example: trees Dicot: example: trees

Stems-Internal

Simple Tissues – consisting of one cell type Parenchyma – thin walled & alive at maturity; often multifaceted. Parenchyma – thin walled & alive at maturity; often multifaceted. Collenchyma – thick walled & alive at maturity Collenchyma – thick walled & alive at maturity Sclerenchyma – thick walled and dead at maturity Sclerenchyma – thick walled and dead at maturity Sclerids or stone cells – cells as long as they are wide Sclerids or stone cells – cells as long as they are wide Fibers – cells longer than they are wide Fibers – cells longer than they are wide Epidermis – alive at maturity Epidermis – alive at maturity Trichomes – “pubescence” or hairs on epidermis Trichomes – “pubescence” or hairs on epidermis Root Hairs – tubular extensions of epidermal cells Root Hairs – tubular extensions of epidermal cells

Parenchyma

Collenchyma

Sclerenchyma Right-hand illustration modified from: Weier, Stocking & Barbour, 1974, Botany: An Introduction to Plant Biology, 5th Ed. SCLERIDSFIBERS

Epidermis – stoma, trichomes, & root hairs

Complex Tissue Xylem – water conducting tissue; parenchyma, fibers, vessels and/or tracheids, and ray cells. Xylem – water conducting tissue; parenchyma, fibers, vessels and/or tracheids, and ray cells. Phloem food conducting tissue; sieve-tube members (no nucleus at maturity, cytoplasm present), companion cells, fibers, parenchyma, and ray cells. In flowering plants, sieve-tube members and companion cells arise from the same mother cell. Phloem food conducting tissue; sieve-tube members (no nucleus at maturity, cytoplasm present), companion cells, fibers, parenchyma, and ray cells. In flowering plants, sieve-tube members and companion cells arise from the same mother cell.

Xylem movement in stem/leaf

Xylem

Phloem

Vascular Bundles with xylem & phloem Maize or Corn – vein in cross section Alfalfa – vein in cross section