Roots, Stems, Leaves, Tissues

1. Roots, Stems, Leaves, Tissues BSC 2011L

2. Review of difference between monocots and dicots

3. Organization of Flowering Plants • 3 vegetative organs that don’t have to do with reproduction: • Root – anchor the plant, and absorb water and minerals • Stem – supports leaves • Leaves – carry on photosynthesis • 3 major tissues of vegetative organs: • Dermal tissue • Outer protective coating of organ • Ground tissues • Interior of plant organ • Vascular tissue • Xylem (transports water) and phloem (transports sugars) • Transports, supports

5. Ground Tissue • 3 cell types according to cell wall structure • Parenchyma • Large vacuoles • Important roles: • Photosynthesis in leaves • Storage of proteins in fruits • Storage of starch in roots • Collenchyma • Generally elongated • Provide support to leaf petioles, nonwoody stems, growing organs • Sclerenchyma • Thickened cell walls for support • Undergo programmed cell death often and offer support then (in wood and bark)

6. Growth • Primary Growth • Increases length of plant • Secondary Growth • Increases girth of plant

7. Growth - Apical Meristem • Located at terminal end of stem, branches, root tip • Continuous growth

8. Growth – Lateral Meristem • The roots and stems of some Eudicots develop secondary plant body – tissues referred to as wood and bark • 2 Lateral Meristems • Vascular Cambium – supplies cells of secondary xylem and phloem which eventually become wood and bark • Cork cambium – waxy protective cells that become bark

9. Root System • Eudicot Root • Monocot Root

10. Roots • Note location of: • Root cap • Zone of cell division • Zone of elongation • Zone of maturation

11. Root Diversity • Types of roots • Taproots – main root is larger and often serves as food storage • Fibrous roots – all of the roots approximately same size

12. Stems • Monocots • Usually herbaceous (non-woody) • Dicots • Some are herbaceous • Trees - woody

13. Stems • Dicot • Monocot

14. Stem Diversity • Other examples: • Rhizomes – horizontal underground stems that can give rise to new shoots • Bamboo • Bulbs – stems with many fleshy layers of leaves that store nutrients • Lilies, onions

15. Anatomy of woody stems – only in dicots • Primary growth • Apical meristem within termnial bud is active • Secondary growth • Vascular cambium is active • Produces new xylem and phloem each year • Build-up of this every year is called wood

16. Woody Stems

18. Dicot Leaves Monocot

19. Leaves Petiole