Plant Growth and Development

Hort I Plant Growth and Development

Primary Plant Parts and Functions

Plant Parts and Function • Terminal bud (apical bud) • Main area of growth on a plant • Produces all the differentiated tissues • including vegetative and reproductive organs • Apical dominance inhibits the growth of axilary buds by producing auxins • Auxins – hormones that prevent lateral growth

Plant Parts and Function • Axillary (lateral) bud • Forms in the axil • Develop from the nodes • Capable of developing into a branch, shoot or flower • Axil • Angle between the upper stem of the plant and a leaf branch

Plant Parts and Functions • Node • Part of a stem from which a leaf, branch or aerial root grows

Plant Parts and Functions • Internode • Part of the stem between two nodes

Plant Parts and Function • Stem • Main structural part of the plant • Has nodes and internodes

Plant Parts and Function • Flower • Reproductive part of the plant • Attracts pollinators to insure seed production • Flower stem • Supports the flower

Plant Parts and Function • Lateral branch/shoot • Branches that grow off the side of the stem

Plant Parts and Function • Leaf • Apex – end opposite the petiole • Margin – edge of leaf • Blade – face of leaf • Vein – Structural Framework of Leaf • Petiole – attaches the blade to the stem • Leaflet – looks like a leaf, but has no petiole (compound leaves) • Stipules-growths at the base of the petioles

Hardwood Plant Parts and Functions • Leaf scar- • Mark left on a branch after a leaf falls • Terminal bud scar/annual rings • Marks left from growth in the previous year • Bundle scars • markings within a leaf scar at the location where vascular bundles were broken as the leaf petiole detached from the twig.

Stem Structures • Epidermis • Outer layer of wax coated cells that provide protection • Cuticle –protective waxy coating produced by the epidermis; thicker on succulents • Cortex • Primary stem tissue; epidermis is outside; phloem is inside

Vascular Bundles • Xylem • Transports water • Provides structure • Phloem • Tissue that moves sugars and nutrtients • Cambium • Single celled layer of meristematic (dividing) tissue adding width to the stem • Forms phloem towards the outside and xylem towards the inside • Pith • Center of dicot plants • Rigid xylem wood fiber

Plant Parts and Functions • Roots • Internally same as stems • Three types • Tap root • Fibrous roots • Adventitious roots

Underground Stem Modifications • Rhizome • Horizontal, underground stem • Capable of producing shoot and root systems of a new plant • Allows for vegetative (asexual)reproduction • Enables a plant to survive annual, unfavorable season (perennate) underground

Rhizome • In some plants, the rhizome is the only stem; only leaves and flowers are readily visible (water lilies, some ferns)

Underground Stem Modifications • Tuber • Short, thickened, mostly underground stem • has minute scale leaves, each with a bud that has the potential for developing into a new plant.

Tubers • Potato, Jerusalem artichoke, yams, caladium

Tuberous Roots • Tuberous roots (not the same as tubers) • Bulbets form at the base of the stem • Root structure, not an underground stem – Dahlias and Begonias • Sweet potatoes are a tuberous root

Underground Stem Modifications • Corm • A round, swollen mass of storage tissue at the base of the stem • Has a basal plat e from which the roots grow • Develops small, peas sized cormels around the top of the old corm • Cormels may be planted and will grow into a new corm • Gladiolus, crocus, tarot

Underground Stem Modifications • Bulb • Made up of five parts • Basal plate; bottom from which root s grow • Primary storage tissue/fleshy scales • Shoot from which the new buds grow • Lateral buds – develop into bulb-lets • Tunic – protective coating

Bulb • Two sub-types of bulbs • Bulbs that have a papery covering, or tunic, are called tunicate bulbs -daffodil. • Bulbs that lack this protective covering (imbricate/nontunicate) must be kept moist at all times – lily

Sub-aerial Stem Modifications • Offset • A shoot that develops laterally at the base of a plant, often rooting to form a new plant. • Example: Succulents like Hens and Chicks

Sub-aerial Stem Modifications • Stolon/runner • Stems which grow at the soil surface, or below the ground and form new plants at the ends or at the nodes

Sub-aerial Stem Modifications • Sucker • A basal shoot, root sprout, adventitious shoot, water sprout • A shoot or cane which grows from a bud at the base of a tree or shrub • May grow from the roots • Takes the form of a singular plant

Aerial Stems • Tendril • Used by climbing plants for support and attachment • Specialized stem, leaf or petiole with a threadlike shape • Can photosynthesize (no lamina or blade) • can be formed from modified shoots, modified leaves, or axilliary branches

Aerial Stems • Thorn • Modified branches/stems • Protect the plant from herbivores

Aerial Stems • Phylloclade/cladode • Flattened green stems that serve as PSN organ • Looks like a leaf

Aerial Stems • Bulbil • Stem modifications that aid in plant reproduction

Flowers • The purpose of flowers is to produce seed. • A plants purpose in life is to reproduce.

Parts of a Flower • Pistil (Carpel) • Female part of flower where egg cell originates • Stigma • Upper part of pistil that catches pollen • Style • Supports stigma • Contains pollen tube • Ovary • Produces ovules which develop into seeds

Parts of a Flower

Parts of a Flower • Stamen • Male part of flower where pollen originates • Filament • Supports the anther • Anther • Bears the pollen

Accessory Organs • Corolla • Petals of the flower

Accessory Organs • Sepals • Modified leaves • Calyx • All of the sepals of the flower

Accessory Organs • Pedicel • Stalk of an individual flower • Peduncle • Attached to the pedicel of many flowers or a single flower

Types of Flowers • Complete • Stamens, pistils, petals and sepals • common in dicots

Types of Flowers • Incomplete • Has stamens and pistils • Petals or sepals or both are missing • Common to monocots

Types of Flowers • Perfect Flower • Has both stamens and pistils on the same flower

Types of Flowers • Imperfect flowers • Has either stamens or pistils • Not both on the same flower

Types of Flowers • Staminate • Only male flower parts • Pistillate • Only female flower parts

Types of Flowers • Monecious • Staminate and pistillate flowers found on the same plant • Corn, cucumbers, squash, melons, pumpkins • Dioecious • Staminate and pistillate flowers on separate plants • Spinach, asparagus, some fruit trees

Types of Fruits: • Pome • Fleshy fruits • Outer, fleshy layer developed from calyx and receptacle • Ovary forms a leathery core containing seeds • Pear, apple

Types of Fruits • Drupe • Ripened ovary becomes two-layered outer forming a pit enclosing a seed • Cherry, peach, plum

Types of Plants • Berry • Ovary is fleshy and unusually juicy • Contains several seeds • Tomato, grape, cucumber

Types of Fruits • Aggregate Fruit • Several pistils in a single flower form compound fruit • Strawberry, raspberry, blackberry

Types of Fruits • Multiple Fruit • Several clusters of flowers form compound fruit • Mulberry, pineapple, fig

Types of Fruits: Dry • Pod • Thin ovary wall • Single chambered, contains several seeds • Splits along line when ripe • Pea, bean, milkweed • Capsule • Several chambers and seeds in ovary • Iris, lily, cotton, poppy

Types of Fruits: Dry Closed • Nut • Ovary wall is hard • Encloses one seed • Oak, acorn, walnut

Types of Fruits: Dry Closed • Achene • Ovary wall isn’t fastened to seed • Dandelion, sunflower

Plant Growth and Development

Plant Growth and Development

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