Ch 35 Introduction to Plants Kingdom: Plantae  Cell wall  Autotroph (photosynthesis)  Multicellular

Agenda History of Life – Open Note Quiz ◦ Powerpoint on Class Page for Review Independent Plant Notes Class Discussion HW: - Finish Flower Worksheets - The Great Plant Escape

Two Types Land Plants  Angiosperms (flowering plants)  ~90% plants  Produce seeds within a fruit  Examples:  Grasses Gymnosperms (naked seeds) - Early plants - Examples -Ferns -Conifers

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

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

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

Modified Roots

Mangrove Forest in Florida

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

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 ◦ XylemPhloem ◦ 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 A. 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

XylemPhloem

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

Key Dermal Ground Vascular Epidermis Root hair Cortex Vascular cylinder Zone of maturation Zone of elongation Zone of cell division Apical meristem Root cap 100 µm Primary Growth of a Root

Primary Growth of Shoots Shoot apical meristem: dome of dividing cells at tip of terminal bud; divide and elongate

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