Chapter 4 Lessons 3 Herbaceous stemsCharacterisitcs:a.Live only one growing seasonb. smaller than a wood stemc. Important to man as cropsd. No annual rings because live only one season
Dicot herbaceous stems:Xylem and phloem cells formfibrovascular bundles arranged inrings around the pith
Dicot herbaceous stems:Xylem and phloem cells form fibrovascular bundles arranged in ringsaround the pithXylem is in the center of the ring and thephloem is on the outside
Monocot herbaceous stemsVascular bundles are scatteredHas a rind or outer covering of thestemUsually has no cambium tissue
· Chapter 4 Lesson 4 · Vegetative Reproduction – asexual reproduction from the stem, leaf or root instead of from seeds. The Encyclopedia. 2000
Vegetative Reproduction – asexual reproduction from the stem, leaf or root instead of from seeds· · Also called vegetative propagation The Encyclopedia. 2000
In asexual reproduction:Offspring are genetically identical toparentExample is a strawberry thatproduces runners
Adventitious roots – roots that growfrom unexpected regions of the plantlike the stem, branch or leaf
Types of Vegetative propagation1.Cuttings – piece of stem or rootplaced in medium (water or soil) androots will grow to make a new plant
Types of Vegetative propagation1. Cuttings2.Layering – when a portion of a stem grows roots while still attached to the parent plant, it will then detach.Ex. Honeysuckle
Types of Vegetative propagation1. Cuttings2. Layering3.Grafting – process of transplanting livingtissue from one plant to another.Ex. grapes
Types of Vegetative propagation1. Cuttings2. Layering3.GraftingAdvantages of grafting: • saves time – get mature plant almost immediately • You get the best attributes of both plants
Types of Vegetative propagation1. Cuttings2. Layering3.GraftingTerms: Scion – part that is grafted in Stock – where the scion isplaced
Types of Vegetative propagation1. Cuttings2. Layering3.Grafting Method is used for McIntosh apples and for grapes It is mentioned in the Bible“If some of the branches have been broken off, and you, though awild olive shoot, have been grafted in among the others and nowshare in the nourishing sap from the olive root, 18 do not consideryourself to be superior to those other branches. If you do, considerthis: You do not support the root, but the root supports you. 19 Youwill say then, "Branches were broken off so that I could be graftedin." 20 Granted. But they were broken off because of unbelief, andyou stand by faith. Do not be arrogant, but tremble. 21 For if God didnot spare the natural branches, he will not spare you either. “
Types of Vegetative propagation1. Cuttings2. Layering3.Grafting4. Budding – a type of grafting where the bud is used as the scion.Typical with apple trees.Shield-budding the mango. On the left, a bud properlyinserted; next, an inserted bud wrapped with a stripof waxed cloth; above the knife-point, a properlycut bud; and on the right, budwood of desirable character.
Types of Vegetative propagation1. Cuttings2. Layering3.Grafting4. Budding5.Tissue culturing• Relatively new process• A cell is placed in a petridish with the propermedium, given hormones, and it willdevelop into a new plant
Important hormones in plants1.Auxin•First group discovered•Important to root and shoot growth intropisms•causes cells in one area to grow longer
Important hormones in plants1.Auxin•Secreted in shoot but mainly affectthe root•Used in root starter when plantingnew plants.
Important hormones in plants1.Auxin2. Cytokinins• promotes cell division•secreted mostly in the roots andaffects the shoot•Auxins and cytokinins work togetherto promote growth
Important hormones in plants1. Auxins2. Cytokinins3.Gibberellins• regulate the proper amount of growth• If you reduce gibberellins you end up with dwarf plants.
Important hormones in plants1. Auxins2. Cytokinins3.Gibberellins4. Abscisic acid•Major role in bud and seedgermination dormancy when plantstressed due to unfavorableconditions•Inhibitory affecton gibberellins
Important hormones in plants1. Auxins2. Cytokinins3.Gibberellins4. Abscisic acid5. Ethylene• responsible for leaf abscission and fruit ripening.
Special stems.1. Bulbs – ex. Onion; designed forfood storage2. Rhizomes – thick stems that grow horizontally under ground Store food Form of vegetative propagation Ex. Iris, grasses
Special stems1. Bulbs2, Rhizomes3. Stolons or runners – stem grows quickly along the surface of the ground (above ground) to produce new plants where a node touches the soilEx. strawberry
Special stems1. Bulbs2. Rhizomes3. Stolons or runners4.Tendrils – a stem where hormonesstimulate the cell on the opposite sideto grow longer where the stemtouches an object causing the stem towind around the objectEx. beans
Special stems1. Bulbs2. Rhizomes3. Stolons or runners4. Tendrils5. Stem Tubers• Modified portion of stem to store food• Also form of asexual reproduction• Ex. Potatoes• Also there are root tubers – ex. yams
Special stems1. Bulbs2. Rhizomes3. Stolons or runners4. Tendrils5. Stem Tubers6. Thorns• Modified portion of stem for protection• Ex. Honey locust• Don’t confuse with spines which are modified leaves
RootsTwo types of roots are:A. Fibrous roots Branching – main central root Monocots have them Ex. grasses
RootsTwo types of roots are:A. Fibrous rootsB. Tap roots Have an enlarged main root Dicots have them Ex. carrots, dandelions
RootsParts of a root cross section:1. Epidermis – outside layer that protects the root from water loss
RootsParts of a root cross section:1.Epidermis•Root hairs – are projections of theepidermis that increase the surfacearea of the root for better waterabsorption.
RootsParts of a root cross section:1.Epidermis •Root hairs2. Cortex – the next layer in from the epidermis and is where food is stored.
RootsParts of a root cross section:1.Epidermis •Root hairs2.Cortex3. Stele – central cylinder of the rootthat contains the xylem and phloem.
RootsThree regions of primary root growth:a. Meristemic region – region closest to the end where cell division takes place
RootsThree regions of primary root growth:a. Meristemic regiona. Region of elongation – just above the meristemic region and is where cells will increase in length pushing the root down
RootsThree regions of primary root growtha. Meristemic regionb. Region of elongationc. Maturation region – where cellsbecome specialized and incorporated inthe stele/cortex.
RootsRoot Cap – is at the end of the root protecting and covering it is several cell layersthick Secretes slime to reduce friction
RootsSecondary Growth or lateral growth: Takes place in the cambium tissue Addition of new xylem and phloem by vascularcambium cells
RootsSpecialized root functions:1. Prop roots adventitious roots that arises from the stem add support Ex. corn
RootsSpecialized root functions:1. Prop roots2. Bald cypress knees Stick above the water Presumed to provideoxygen to other roots butno scientific evidence Give added support?? Purpose unknown
Roots Specialized root functions: 1. Prop roots2. Bald cypress knees3. Desert plant roots– secrete chemical inhibitors to keep other plants from growing nearby.