Chapter 35: Plant Structure, Growth, and Development 35.1 Admit Slip 3. List 3 words you think of when you look at the picture/diagram 2. Write 2 ideas you have based on the picture and your words. If possible, use your words as you write your ideas. 1. Write 1 question you have.

Plant Structure Plants have hierarchies of cells, tissues, and organs Root system- Shoot system Plant Organs (leaf, stem, root) Differentiated cells (parenchyma, collenchyma, sclerenchyma, xylem, and phloem)

Root System Beneath the ground Structural Characteristics Anchors plant Absorbs water and minerals Stores sugars and starches Structural Characteristics Fibrous roots: thin root mats below surface Taproots: one thick vertical root with many lateral roots Root hairs: increase surface area for absorption. May include a symbiotic relationship with mycorrhizae (fungus roots)

Shoot System Above ground Consists of stems and leaves Structural characteristics Terminal bud: top of the stem where growth occurs. Growth toward light (upward) is accomplished by apical dominance (terminal bud prohibits axillary bud growth) Axillary bud: located in V formed between the leaf and stem (lateral shoot/branch) Leaves: main site of photosynthesis

Modified shoots stolons (strawberries) rhizome (ginger) tuber (potato) Rampart HS 11/23/2018 Modified shoots stolons (strawberries) rhizome (ginger) 2009 tuber (potato) bulb (onion) Follett

Modified leaves tendrils (peas) spines (cacti) succulent leaves Rampart HS 11/23/2018 Modified leaves tendrils (peas) spines (cacti) succulent leaves 2009 colored leaves (poinsetta) Follett

Plant Tissue Types Leaves, stems, roots are made up of: Dermal tissue: single layer of cells that protects against water loss and pathogens (called the cuticle in leaves) Vascular tissue: transports material between the roots and shoots Xylem: transports water and minerals Phloem: transports food from leaves to the rest of the plant Ground tissue: “everything else” If it is inside the vascular tissue=pith, outside the vascular tissue=cortex

Types of Differentiated Plant Cells Parenchyma Collenchyma Sclerenchyma Xylem Phloem

Types of Differentiated Plant Cells Parenchyma: most abundant, present throughout plant Perform most of the metabolism including photosynthesis Collenchyma: help support growing parts of the plant Strings of celery are vascular tissue with collenchyma surrounding it Sclerenchyma: exists in parts of cell that are no longer growing, specialize in support

Types of Differentiated Plant Cells Xylem: consist of 2 types of water conducting cells: tracheids and vessels (dead at functional maturity) Tracheids: long, thin cells with thick secondary cell walls (lignin). Water moves between cells through pits Vessels: (mostly in angiosperms) pits and perforated end walls for water movement

Types of Differentiated Plant Cells Phloem Cells: conduct sugar and other organic compounds Two types of cells (both alive at functional maturity): Sieve tubes: contain chains of cells (sieve-tube elements)-highly specialized to function in transport Companion cells: provide for molecular needs of sieve-tube elements. Connected to sieve-tube elements by plasmodesmata

Chapter 35: Plant Structure, Growth, and Development 35.2

Meristems Flowering plants are classified as: Annuals: life cycle completed in 1 year Biennials: life cycle completed in 2 years Perennials: life cycle continues for many years Meristems are perpetually embryonic tissues that are responsible for plant growth throughout it’s life

Meristems Growth only occurs in meristem tissue through cell division Apical meristem: located at tips of roots and buds of shoots. Site of cell division. Growth in length=primary growth Lateral Meristems: growth that thickens the shoots and roots Growth in ‘girth’=secondary growth

Primary growth lengthens roots and shoots Root cap: protects meristem of root tip as it moves through soil, also secretes polysaccharide lubricant Has 3 zones: Zone off cell division Zone of elongation Zone of maturation

3 zones of root tip Zone off cell division: includes root apical meristem. Produces new root cells (including cells of root cap) Zone of elongation: cells elongate… Zone of maturation: 3 systems in primary growth complete differentiation and mature

Shoot Epidermis Ground tissue Apical meristem is dome of dividing cells at the tip of a terminal bud Primary growth is accomplished by cell division and cell elongation Epidermis Underside of leaf epidermis has stomata (small pores which open and close) Ground tissue Sandwiched between the upper and lower epidermis Made of parenchyma cells (photosynthesis)