Ch 35 WarmUp 1 Draw and label the

Ch. 35 Warm-Up 1. Draw and label the 3 main organs of a plant. 2. What are 3 ways that plant cells differ from animal cells? Most H 2 O and minerals taken up from the soil by a plant are absorbed by _______. 4. The main photosynthetic organs of a plant are the _____. 3.

Ch. 35 Warm-Up 1. List the 3 types of plant tissues. What is the function of each type? 2. What are meristems? Where are they located in a plant? 3. What effect does “pinching back” a house plant have on the plant?

Chapter 35 Plant Structure, Growth, and Development

What you must know The function of xylem and phloem tissue. The anatomy of a leaf The anatomy of a root

Introduction to Plants Kingdom: Plantae Cell wall Autotroph (photosynthesis) Multicellular Angiosperms (flowering plants) ~90% plants Produce seeds within a fruit Key adaptations: flowers & fruits

Plant Organization Organs • Roots • Stems • Leaves Tissues • Dermal • Vascular • Ground Cell Types • Xylem • Phloem • Parenchyma

I. Plant Organs Shoot system • Above ground • Stems, leaves Root system • Underground (usually) • Roots

A. Roots § Anchors plant, absorbs H 2 O & minerals, stores sugars/starches § Root hairs – tiny extensions of epidermal cells, increase surface area for H 2 O and mineral absorption § Mycorrhizae: fungus + plant root symbiotic relationship Root hairs

Fibrous Roots Taproots Mat One of thin roots spread just below surface Shallow Increased surface area Fibrous Root (scallion) thick, vertical root Many lateral (branch) roots Firmly anchors Stores food Taproot (carrot)

Modified Roots

Mangrove Forest in Florida

B. Stems Function: display leaves § Terminal bud: growth concentrated at top end of stem § Secretes hormone to prevent growth of axillary buds; growth directed upward, toward light § Axillary buds – located in V between leaf and stem; forms branches (lateral shoots) § Pinching/pruning – removing terminal bud

Modified stems Runner or stolin ◦ Aspen, strawberries, grass ◦ Grow on surface ◦ For asexual reproduction Rhizome ◦ ◦ Iris, ginger, potato, onion Grow underground Store food & DNA for new plant Tuber: end of rhizome Bulb – underground shoot ◦ Onion ◦ storage leaves

C. Leaves Function: Photosynthetic organ blade petiole

Modified leaves

II. Plant Tissues

A. Dermal Tissue Single layer, closely packed cells that cover entire plant Protect against water loss & invasion by pathogens (viruses, bacteria) Cuticle: waxy layer

B. Vascular Tissue Continuous throughout plant Transports materials between roots & shoots ◦ Xylem & Phloem

C. Ground Tissue Anything that isn’t dermal or vascular Function: storage, photosynthesis, support Pith: inside vascular tissue Cortex: outside vascular tissue

III. Cell Types Xylem Conducts H 2 O and minerals up from root Dead, tubular, elongated cells B. Phloem Conducts sugar & organic compounds from leaves to other parts of plant Living cells aid movement of sugar 2 Cell Types: sieve tubes, companion cells A.

Xylem Phloem

Plant Growth Types of Flowering Plants: Annuals – 1 year life cycle Biennials – 2 years Perennials – continuous life cycle for many years Meristem: perpetually embryonic tissues ◦ Cells divide for plant growth Ø Apical meristem: growth at tips of roots & buds of shoots; cause primary growth (increase length) Ø Lateral meristem: growth thickens shoots and roots; secondary growth

Primary and Secondary Growth

Root Anatomy Root Hairs Zone of Maturation: primary growth becomes functionally mature Zone of Elongation: cells elongate; push root tip ahead Zone of Cell Division: apical meristem; new cells produced (mitosis) Root cap: protects meristem as it pushes through soil

Leaf Anatomy ◦ Epidermis of underside interrupted by stomata (pores), flanked by guard cells (open/close stomata) ◦ Mesophyll: ground tissue between upper/lower epidermis ◦ Parenchyma: sites of photosynthesis

Secondary Growth = increase diameter Involves lateral meristems ◦ Vascular cambium: produces secondary xylem (wood) ◦ Cork cambium: produces tough covering that replaces epidermis Bark = all tissues outside vascular cambium

Secondary phloem Vascular cambium Secondary Late wood Early wood xylem Primary and secondary growth in a two-year-old stem Cork cambium Periderm Cork Epidermis Cortex Primary phloem Vascular cambium Primary xylem Pith Primary xylem Vascular cambium Primary phloem Cortex Phloem ray Xylem ray h rowt G Primary xylem Secondary xylem Vascular cambium Secondary phloem Primary phloem First cork cambium Periderm (mainly cork cambia and cork) Primary phloem Secondary phloem Vascular cambium Secondary xylem Primary xylem Pith 0. 5 mm Cork th Secondary xylem (two years of production) Vascular cambium Bark Most recent cork cambium Cork Bark 0. 5 mm Primary and Secondary Growth of a Stem Grow Secondary phloem Xylem ray Epidermis Transverse section of a three-yearold Tilia (linden) stem (LM) Layers of periderm