Plant Kingdom Biology 112

Kingdom Plantae The term plant is used to include organisms that share the following characteristics: Ability to synthesize carbohydrates by photosynthesis Presence of cellulose cell walls Alternation of generations in their life cycles Lack of mobility

The gametophyte generation begins with a spore produced by meiosis The gametophyte generation begins with a spore produced by meiosis. The spore is haploid, and all the cells derived from it (by mitosis) are also haploid. In due course, this multicellular structure produces gametes — by mitosis — and sexual reproduction then produces the diploid sporophyte generation.

Plant Diversity As environments change so do species Land plants have adapted with the evolution of structures and systems for the transport of water; roots, stems and leaves; and a method of reproduction that did not depend on water for the dispersal of gametes As plants became more complex they depend on water less for reproduction

Classification Scientists have devised a number of classification schemes for plants. The 3 main groups we will look at are: AQUATIC NONVASCULAR VASCULAR

Aquatic Plants The simplest of plants live surrounded by water b/c it satisfies their needs: nutrients, moisture, spore dispersal. Most are green, brown and red algae Most are multicellular The multicelled body is called a thallus and lacks conductive tissue as well as true roots, stems, and leaves.

Adaptations for a Terrestrial Lifestyle Mosses, liverworts, and ferns, gave rise to more complex terrestrial plants that bear seeds and flowering plants. The two lineages are divided into vascular and nonvascular plants Vascular tissue is conducting tissue called the xylem and phloem. These allow for transport of water and nutrients throughout the plant.

Vascular and Non Vascular Both vascular and nonvascular plants have a waxy protective cuticle, numerous stomata and complex reproductive structures. The cuticle is a non cell layer secreted by the epidermal cells which keep the plant from drying out. Stomata are pores in the epidermis of plants, usually in leaves. Allow for exchange of gases.

STOMATA Guard Cells Chloroplasts Nuclei

NONVASCULAR “LAND” Plants Also called bryophytes Confined to moist habitats b/c they need water for sexual reproduction Commonly found in wetlands, rain forests, and roadside ditches Generally less than 20cm tall 3 classes: mosses, liverworts, and hornworts

Bryophytes Have leaflike, stemlike and rootlike organs Have rhizoids (root-like filiments) that anchor the plant Water and nutrients move from cell to cell by diffusion Mosses are the most common and they hold a lot of water – this sponge like feature makes them useful in oil spills, and potting soils Ex: used sphagnum (moss) as a maxipad long ago

Vascular Plants Division Tracheophyta which includes the “true” terrestrial plants such as the familiar ferns, shrubs, trees, and flowering plants They transport nutrients, water and minerals via a vascular system With the exception of ferns, vascular plants have evolved reproductive structures that are free of total dependence on water

Vascular Structure The vascular tissue provides a continuous internal conduction system between roots, stems and leaves. It also provides structural support

Two Types of Vascular Plants Those that produce seeds Those that do not produce seeds

Seedless Plants Dominant land plant 300 million years ago Most are now extinct

Seed Plants Reproductive Adaptations and an improved vascular system largely account for the success of seed plants The most widely distributed and complex group of plants on Earth 270 000 known seed plants Have separate male and female gametophytes, as well as roots, stems and leaves.

Seed Plants Seed type is the main criterion for distinguishing the two major seed-bearing groups; gymnosperms and angiosperms Greek: sperma “seed”, gymnos “naked”, and angeion “vessel” Gymnosperms produce unprotected or “naked” seeds in conelike structures, and Angiosperms produce seeds that are enclosed and protected inside the fruit, which is formed by the flower. Seeds ensure the survival of seed plants by resisting desiccation.

ANGIOSPERMS (Flowering Plants)

Characteristics of Angiosperms There are thousands of different kinds of flowering plants They range from tiny pond-surface plants, which are less than 1mm long to trees 100m tall. Angiosperms ALL produce seeds in reproductive structures called flowers. Then, as the seeds mature, the flower changes into a fruit. The name angiosperm means “covered seed” Mature seeds are scattered, or dispersed, along with the fruit

Monocots and Dicots Botanists are able to divide the 235,000 species of angiosperms into two large groups based on the structure of their seeds Inside the seeds of angiosperms are tiny embryonic leaves called cotyledons. The seeds of one group of angiosperms have one cotyledon, called monocotyledons or monocots. Other angiosperms have two cotyledons. These are called dicotyledons or dicots

Monocots and Dicots They also have distinctive patterns of veins in their leaves. The veins of monocot leaves are parallel to each other The leaves of dicots usually have netlike veins

Monocot Examples Tulips, daffodils, irises, lilies, palm trees

Dicot Examples Buttercups, peas, roses, sunflowers, maple trees, and dandelions

Grass? The leaf blade of grasses indicates whether they are monocots or dicots based on leaf veins. To which group do grasses belong? You are right if you said monocots!

Page 453 of Text Draw Figure 19.14 here!

GYMNOSPERMS

Gymnosperms Represent all seed plants that DO NOT form flowers (therefore do not have seeds enclosed within a fruit) The most numerous and widespread are the conifers (cone bearing)

Conifers Cone bearing woody trees and shrubs Leaves are usually needlelike Most are evergreen (don’t drop their leaves in the Autumn) Conifers DO shed their needles, just not all at once – usually 2 to 4 years Grow in many different environments 600 species (pine, fir, spruce, cedar, hemlock, sequoias Produce useful products, ie. lumber/paper

Typical Conifer Life Cycle Copy Figure 19.10 into your notebook

Summary of Life Cycle Female cone is closed and sticky with resin Pollen (from male) lands on the female cone Meiosis begins and the embryo forms Once the seed is fully mature, the cone scales open up and the seeds are dispersed via wind, animals, water, etc…..

Plant Structure & Development Like the human body, plants contain many different types of cells, tissues, and organs. Plants are structurally less complex than animals and have fewer types of cells A plant is composed of many repeating units (like an apartment) In seed plants, these units are organs such as leaves, roots, flowers and stems. Each organ acts as a separate unit. A plant may react to stress by varying the number of its parts

Organs of Seed Plants Seed plants have specialized organs for growth and reproduction Vegetative organs – roots, stems, and leaves, function in the growth of the plant. The reproductive organs of seed plants include cones, flowers and fruits

ROOTS Are organs that are specialized to collect water and dissolved minerals Water is necessary for photosynthesis and metabolism Anchor the plant and store food They may extend deep into the ground or far from the plant

STEM The parts of a plant above the soil surface make up the shoot system. A stem is an organ that conducts water and minerals from the roots to the other parts of the plant Displays the leaves of the plant to the light The point on the stem where the leaf is attached is called a node Store food

LEAVES Main food factories of seed plants. Center of photosynthesis Somewhat flattened to allow maximum collection of light energy They transport food to the stem to be used by the rest of the plant Collectively the leaves are called the canopy.

Plant Tissues Roots, stems, leaves, flowers and cones are all composed of tissues Each type of tissue consists of cells with distinct structures and functions. Some tissues consist of dead cells, whereas other types are living and metabolizing.

Plant Tissue All seed plants have common tissues: meristematic tissue, epidermis, parenchyma, supportive tissue, and vascular tissue.

Meristematic Tissue Plants, unlike animals, continue to grow throughout their lives. All plant growth originates in meristems. A meristem is a growing point of a plant consisting of unspecialized cells that are continually dividing and producing new cells. Meristems at the tip (or apex) of a root or stem are called apical meristems. These cause an increase in the length of a plant body Another kind of meristem, called the cambium, causes a plant to grow in width.

Meristematic Tissue

Epidermis A tissue that covers the entire plant body Helps reduce water loss Covered by a waxy cuticle (acts like a lip balm) Do you think the epidermis of roots has a waxy cuticle?

Parenchyma Tissue that is generally unspecialized Serves a variety of functions Parenchyma cells store sugars and starches When a plant is wounded, these cells begin to divide to heal the wound In leaves, some types of parenchyma have chloroplasts and carry on photosynthesis.

Vascular Tissue Supports the plant It conducts food, water and dissolved minerals from one part of the plant to another. Serves as the plants “plumbing system” Two types of vascular tissues: Phloem – transports sugars and starches from one part of a plant to another Xylem – used for the transport of water and dissolved minerals

Heath Text Continue on Chapter 23 (pg. 376) Chapter 24 (pg. 394)