Plant Tissues and Organs

Fig. 38.6

  Modular construction of a shoot

Basic Plant Morphology

• TISSUES- a group of cells functioning together in some specialized activity

• MERISTEMS- a mass of self-perpetuating cells, which are not yet committed to developing into a specialized cell type – Terminal meristems- ends of stems, branches

and roots– Axillary meristems- base of leaves, branches– Lateral meristems are parallel to sides of plant

parts and increase girth.

Meristem types

• Primary– Apical Meristems

• Secondary– Vascular cambium– Cork Cambium

Flowering plants have 3 basic tissue types

• Dermal– Cover surface of plant– Protection

• Ground• Vascular

– Conducting tissue

Dermal

• Epidermis– epidermal cells

• Periderm– cork cells

Fig. 38.12a

Fig. 38.12b

Fig. 38.12c

Vascular Tissue

• Xylem– Mostly to conduct water and nutrients– E.g., roots to shoots

• Phloem– Mostly to conduct sugars, amino acids, etc.– E.g., leaves to roots or flowers

Fig. 38.13a

Fig. 4.6

Fig. 4.9

Fig. 38.13b

Fig. 38.14a

Fig. 38.14b

Vegetative Organs

• Roots• Stems• Leaves

Function of roots

• Anchor the plant• Absorb water and minerals from soil• Storage

Longitudinal section of roots

• Root cap• Zone of cell division• Zone of cell

elongation• Zone of maturation

Cross section of root• Vascular bundle (Stele) = contains xylem and phloem• Cortex• Epidermis• Root hairs

– Absorb water and minerals

Fig. 38.15

Fig. 38.21

Function of Stems

• support leaves to maximize light absorption• part of conduit for transport of water,

minerals, and organic solutes• storage

Fig. 38.25a

Fig. 38.25b

Woody dicots

• Discrete vascular bundles replaced by continuous rings of xylem

• Each ring is xylem produced during one growing season

• Vascular cambium

Fig. 38.7a

Fig. 38.7b

Stems: Secondary growth• Vascular tissue, (xylem) makes up the bulk of the stem• Form tree rings

Fig. 38.23

Fig. 38.28a

Fig. 38.28b

Fig. 38.28c

Function of leaves

• Main photosynthetic structure

Leaf parts

• Blade• Petiole• Pair of stipules

Fig. 38.34

Fig. 38.8

Fig. 38.33

Fig. 38.30