Ch. 35 Warm-Up Draw and label the 3 main organs of a plant. What are 3 ways that plant cells differ from animal cells? Most H2O and minerals taken up from the soil by a plant are absorbed by _______. The main photosynthetic organs of a plant are the __________.

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

Plant Structure, Growth, and Development 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 Tissues Cell Types Roots Stems Leaves Dermal Vascular Ground Cell Types Xylem Phloem Parenchyma

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

A. Roots Anchors plant, absorbs H2O & minerals, stores sugars/starches Root hairs – tiny extensions of epidermal cells, increase surface area for H2O and mineral absorption Mycorrhizae: fungus + plant root symbiotic relationship Root hairs

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

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 Rhizome Bulb – underground shoot 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 petiole blade

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 H2O and minerals up from root Dead, tubular, elongated cells 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

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 Apical meristem: growth at tips of roots & buds of shoots; cause primary growth (increase length) 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

Primary and Secondary Growth of a Stem in a two-year-old stem Secondary phloem Vascular cambium Cork cambium Secondary xylem Late wood Early wood Periderm Cork Epidermis Cortex Pith Primary phloem Primary xylem Vascular cambium Transverse section of a three-year- old Tilia (linden) stem (LM) Vascular cambium Primary phloem Cortex Epidermis Xylem ray Primary xylem Bark Phloem ray Growth Pith Xylem ray 0.5 mm 0.5 mm Primary xylem Primary and Secondary Growth of a Stem Secondary xylem Vascular cambium Secondary phloem Primary phloem First cork cambium Cork Periderm (mainly cork cambia and cork) Growth Primary phloem Secondary phloem Secondary xylem (two years of production) Vascular cambium Secondary xylem Vascular cambium Secondary phloem Primary xylem Bark Most recent cork cambium Pith Layers of periderm Cork