Hort I PLANT GROWTH AND DEVELOPMENT Primary Plant

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

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

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

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

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

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

Primary 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 and nutrients Provides structure Phloem Tissue that moves sugars 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

Primary 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 lillies, 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.

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

Types of Fruits: Dry Closed Grain Ovary wall is thin and fastened securely to a seed Corn, wheat, oats

Types of Fruits: Dry Closed Samara Winged fruit Wing attached to the ovary wall Maple, elm, ash