1. Plants II
Plant organs

2. Plant organs Root system – roots Shoot system – stem and leaves
Vegetative organs – (allow to live and grow): roots, leaves, stem
Reproduction: flowers, seeds and fruits

3. Roots Underground, usually equal to shoot system in size
Anchors and gives support
Absorbs water and minerals
Penetrates soil as it grows
Root hairs increase surface
area
Produce hormones

4. stems Main axis of plant
Support leaves so that leaves are exposed to as much light as possible
Node – where leaf is attached
Internode – space between nodes
Vascular tissue used in transport
Can store nutrients and water and conduct photosynthesis

5. leaves Photosynthesis
Size, shape and texture vary and is used in identification
Blade – wide portion of leaf
Petiole – stalk, attaches blade to stem
Axillary bud – where branch or flower may originate

6. Monocot vs Eudicot fig 25.3
Compare seed leaf, root, stem, leaf and flower
Monocot – 1 seed leaf, xylem and phloem in a ring, vascular bundles scattered, leaf veins parallel, flower parts in 3’s and multiples of 3
Eudicot – 2 seed leaves, phloem between arms of xylem, vascular bundles in ring, leaf veins in net pattern, flower parts in 4’s, 5’s
Eudicots make up larger group and include most familiar flowering plants
Monocots include grasses and most of food sources, like rice, wheat and corn

7. Plant tissues Meristematic tissue = embryonic
Apical meristem – located on tip of stem and roots, growth
produces 3 types of meristem
Protoderm epidermis
Ground meristem  ground tissue
Procambium  vascular tissue
Woody (non herbaceous), non woody (herbaceous – perennial, dies back in winter)

8. Epidermal tissue Forms outer protective covering of plant
Walls of epidermal cells exposed to air are covered with a waxy cuticle
Roots – form root hairs
Stems and leaves – trichomes – hairs that protect form too much sun and moisture reserve
Leaves – guard cells, stomata
Periderm – old woody plants, replaces epidermis
Cork cells – protection
Cork cambium – new cork cells made from
Lenticels – areas of overproduction of cork cells, gas exchange

9. Ground tissue Bulk of a plant 3 types:
Parenchyma cells – most abundant, found in all organs of plant, least specialized
Collenchyma – thick primary walls, flexible support to immature regions, celery strand
Sclerenchyma – thick secondary walls that contain lignin (make walls tough), support mature region of plant

10. Vascular tissue Xylem – water and minerals, roots to leaves
Phloem – sucrose and organic molecules (hormones) form leaves to roots
Complex tissues – contain 2 or more kinds of cells
Both extend from roots to leaves
Roots- located in vascular cylinder, stem – vascular bundles, leave – leaf veins

11. Xylem figure 25.6 2 types of conducting cells, hollow and non-living
Tracheids – tapered ends, contain pits where secondary wall does not form
Vessel elements – larger, perforation plates
Parenchyma cells that store substances

12. Phloem – fig 25.7
Sieve tube members – continuous sieve tube – no nucleus
Companion cells – have nucleus
Connected to sieve tube member by plasmodesmata

13. Root organization Root cap – apical meristem, replaced often Zones
Cell division – primary meristem, mitosis
Elongation – cells lengthen and specialize
Maturation – root hairs, fully differentiated

14. Eudicot root tissue Epidermis – single outer layer, root hairs
Cortex – thin walled parenchyma, food storage
Endodermis – boundary between cortex and vascular tissue
Casparian strip – prevents water and mineral ions between cell walls
Vascular tissue – xylem and phloem
Pericycle – first layer of cells
Monocots similar, differ in arrangement of xylem and phloem in a ring, ground tissue is pith

15. Root diversity
Taproot – grows straight down, fleshy, stores food, carrot, beet
Fibrous root system – in monocots – seen in grasses, strong anchorage
Adventitious roots – develop from shoot system instead of root system, seen in corn, can come above soil line
Root nodules – beans, peas…, nitrogen fixation
Mycorrhizae – plant roots and funugs

16. Stem organization Terminal bud – shoot tip protected by bud scales
Leaf and bundle scars – location of leaves that have dropped
Axillary buds – give rise to branches or flowers
Bud scale scar – indicates age of stem, one for each year of growth
Primary meristem  primary tissues
Protoderm  epidermis
Ground meristem  pith (ground tissue)
Procambium  cortex (vascular tissue)

17. Herbaceous stems Non woody, die off in winter, perennial
Only primary growth
Eudicot, vascular bundle in rings, cortex separate from pith
Monocot – vascular bindles scattered, no well defined cortex or pith

18. Woody Stems Primary (length) and secondary (girth of trunks) tissues
Secondary tissues form from lateral meristem: vascular cambium and cork cambium
Vascular cambium produces new xylem and phloem each year
3 distinct areas: bark, wood and pith

19. Bark and Wood Contains periderm Wood is secondary xylem, girth
when stem becomes woody, replaces epidermis
Cork, cork cambium and phloem
Removing bark and be fatal to tree
Wood is secondary xylem, girth
Vascular cambium is dormant in winter
Annual ring – sapwood, inner rings - heartwood

20. Stem diversity
Stolons – aboveground horizontal stems, reproduce where nodes touch ground, runners, strawberries
Rhizomes – underground, horizontal stems, some contain tubers (food storage) like potatoes
Corm – bulbous underground stems, gladiolus

21. Leaf organization Consist of blade and petiole
Veins are netted in eudicots, parallel in monocot

22. Cross section leaf Trichomes – protective hairs
Cuticle – prevent desiccation but prevent gas exchange
Stomata on underside
Mesophyll tissue
Palisade
spongy

23. Leaf diversity Simple Compound Arrangement
Pinnately compound
Palmately compound
Arrangement
Alternate
Opposite
Whorled
Leaves based on adaptation to environment