Science

Plant Lab Procedure and Data Sheet

Supplies Needed (Get these before beginning the lab exercises):

· Flowering plant (entire plant with flower, leaves, stem, and roots)

· Paper

· Knife *BE CAREFUL WHEN USING A KNIFE*

· Camera or device with camera

Introduction

Plants are complex multicellular autotrophs, producing their own food through photosynthesis. Plants evolved from green algae with four major innovations: alternation of generations, vascular tissue, seeds, and a reproductive approach that includes flowers and fruits. Plant life cycles involve alternation of generations, with a haploid gametophyte alternating with a diploid sporophyte. In more recently evolved plants, there is less time spent in the gametophyte stage. Vascular tissue allows for the transport of materials (water, minerals, sugar) throughout the plant rather than relying on diffusion; this allows the plant to grow taller and live in more variable habitats. Seeds provide protection and nutrients for the developing embryo. Flowers and fruits improve the chances of successful mating and distribution of seeds.

Group 1: Nonvascular Plants

These are plants without complex conducting tissues for water, dissolved minerals, and sugars. Liverworts and hornworts don’t have any vascular tissue at all. Mosses don’t have true vascular tissue, but they do have some specialized cells for conducting water and carbohydrates through the plant. The life cycles of all three of these groups are dominated by the gametophyte stage. Because the sperm must swim to the egg for fertilization, these plants require water for reproduction. None of these plants have seeds, using spores instead, so they are sometimes referred to as the “seedless nonvascular plants.” Three Phyla include Hepaticophyta (Liverworts), Anthocerophyta (Hornworts), and Bryophyta (Mosses)

Group 2: Seedless Vascular Plants

Seedless vascular plants are plants that have specialized vascular tissue ( xylem and phloem) to conduct water and food products throughout the plant. These plants can grow tall through primary growth and expand in diameter through secondary growth due to vascularization. However, these plants lack seeds and reproduce with spores like the nonvascular plants. They also require water for fertilization to occur since the sperm must swim to the egg. Two Phyla Include Lycophyta (Club mosses) and Pterophyta (Ferns, horsetails, whisk ferns).

Groups 3 and 4: The Seed Plants

Vascular seed plants have vascular tissue (xylem and phloem), and the plants contain separate male and female gametophytes. In addition, the sporophyte becomes the dominant structure in the life cycle. The male gametophyte ( pollen) produces sperm that is carried to the egg (contained in the female gametophyte). Pollination in seed plants does not require water as in the other groups. The seed itself provides protection for the plant embryo, by surrounding the embryo and its food in a drought-resistant container. The storage of food with the embryo improves the likelihood the embryos will survive because dormancy periods are possible; this allows the seed to germinate when environmental conditions are more likely to allow the new seedling to survive. The food stored in the seed also allows the embryo to have nourishment during germination and while the leaves are not yet mature enough to photosynthesize.

Group 3: Gymnosperms are the nonflowering vascular seed plants. They produce seeds in cones where pollination occurs. Pollen, produced in separate cones, travels by wind to the seed-bearing cones, where fertilization of the egg takes place. The seed disperses the embryo. Four Phyla include Coniferophyta (Pines, spruce, fir, redwood, cedars), Cycadophyta (Cycads, sago palms), Gnetophyta (Shrub teas, Mormon Tea, Welwitschia), and Gingkophyta (Ginkgo trees).

Group 4: Angiosperms are the flowering vascular seed plants. The flowers are reproductive structures. The colorful petals (and often nectar offerings) attract pollinators. Flowers improved the efficiency of mating because the plant no longer relies on water or wind to deliver the sperm to eggs for fertilization. However, note that some angiosperms are wind-pollinated. Angiosperms are divided into two general groups: monocots and dicots. Monocots have one cotyledon (seed leaf), parallel veins in the leaves, and flower parts in multiples of threes. Dicots have two cotyledons (seed leaves), netlike veins (in a branched network) in the leaves, and flower parts in multiples of four or five. All Angiosperms belong to Phylum Anthophyta (Oak trees, grasses, corn, wheat, any flowering plant).

Vascular Plant Anatomy

Vascular Plant Tissues

A vascular plant can be organized into some main structures. Simplistically, the root is the portion of the plant found below ground, and the shoot is the part of the plant found above ground; although the shoot can sometimes extend underground, and sometimes roots reach above ground. The roots penetrate the soil and absorb water, minerals, and nutrients, as well as acting like an anchor for the plant. The stem acts like a frame to position the leaves, where most photosynthesis takes place.

Often, plants are divided into four categories of tissue. The organs of a plant, like the roots, stem, leaves, and in some cases, flowers and fruit, are composed of different tissues. A plant tissue is a specialized, organized group of cells whose structures are related to their function. There are three main types of plant tissue: ground tissue (where the vascular tissue is embedded), dermal tissue (the outer protective covering of the plant), and the vascular tissue (conducts water and dissolved minerals up from root to shoot and the products of photosynthesis from “source to sink” throughout the plant). Meristems are the areas where a plant grows and will be discussed here as well.

Meristems

Meristems are zones of growth for the plant and are made up of unspecialized cells which are actively dividing. The meristem itself is self-sustaining: one cell becomes two, and one of those daughter cells specializes and matures while the other one remains a dividing meristematic cell. In primary growth, plants add tissues to the tips of their roots and shoots and grow from their ends (called apical meristems). In secondary growth, or growth in thickness, plants grow in width from lateral meristems.

Ground Tissue

Ground tissue makes up the body of the plant and contains three main cell types. Parenchyma cells are the most common, and they carry out functions like photosynthesis, as well as food and water storage. The edible parts of fruits and vegetables are usually parenchyma cells. Collenchyma cells form strands providing support for the plant. Sclerenchyma cells have very thick secondary cell walls providing strength and rigidity for the plant. Some might be fibrous, and others are grainy (think about the gritty texture of pears).

Dermal Tissue

This is the outer layer of the plant body, which consists of epidermal cells covered with a waxy protective coating called the cuticle. Specialized cells in the dermal tissue include guard cells; the space between the guard cells (the stoma) allows for gas exchange between the plant and the atmosphere. Other specialized cells include the root hairs, which are epidermal extensions that increase surface area of the root for water and dissolved nutrient uptake.

Vascular tissue

Vascular tissue includes xylem and phloem. Xylem conducts the water and dissolved minerals through cells that are dead when functionally mature. Water is conducted from root to shoot; that means water is brought in through the roots from the soil and moved through the plant to the leaves. Phloem conducts the sugars and products of photosynthesis through cells that are alive when functional. Sugars are moved from source to sink; that means they are sent from where they are produced to wherever the plant needs them.

The Plant Body

Roots are organs adapted to absorb minerals and water from the soil. Vascular tissue is found in the core of the root, and an apical meristem is found at the root tip. To protect new cells in meristem from the soil particles around the plant, a root cap is found at the tip. Roots can be fibrous (with branching, equally-sized, vein-like roots to anchor the plant) or taproots (storing food and anchoring the plant with a large primary root).

Stems serve as a structural support to position leaves to catch sunlight. Primary growth allows the plant to grow from its tips, and secondary growth allows the plant to grow in width. Wood, the product of secondary growth, is the accumulation of xylem.

Leaves are the primary site for photosynthesis. They are varied in shape and in arrangement, but most have a petiole (or leaf stem) that attaches it to the stem. The veins of the leaf are actually vascular bundles, containing both xylem and phloem. Generally, leaves have more stomata on their undersides for gas exchange and more photosynthetically active cells along the top surface of leaves, where they are protected by a waxy cuticle.

Lab Procedure

Procedure 1: Classification of plants

Observe the four groupings of plants in Figure 1 (labeled Group A, Group B, Group C, and Group D). Each group has representative members of a different plant phylum. Based on the descriptions in the introduction, your text book, and any reliable web resources, determine the plant group represented by sample. You may zoom in on this page to view the picture in more detail using the zoom bar on the bottom right corner of MS Word. Fill out Table 1 with your observations.

Figure 1. Four Plant Groups to Identify

Table 1. Identification of Plant Groups

Plant Group in Figure 1	Notable plant characteristics	Plant group represented (Nonvascular, Seedless Vascular, Gymnosperm, or Angiosperm)
Group A
Group B
Group C
Group D

You will need the data in Table 1 for your Lab 10 Quiz in Canvas.

Procedure 2. Angiosperm Dissection

*BE CAREFUL WHEN USING A KNIFE*

In this procedure, you will be dissecting an angiosperm plant. You will need to provide your own flowering plant (complete with roots, stem, leaves, and at least one flower). You may collect such a plant from nature (but not a protected preserve, of course) or your own yard or garden, or you may purchase one from a plant seller, such as a garden center at a home improvement or big box store.

You will also need to be able to take digital pictures of your plant to upload to the Canvas quiz. A digital camera, web camera, or cell phone camera will suffice.

Part 2A: Photograph & Observe the Intact Plant

Before you begin to dissect the plant, observe its roots, stem, leaves, and flower(s). Note that you will have to remove the plant from soil to see the roots.

1. Write your name (first and last) and the date on a piece of paper or notecard. Take a photo of this paper (with name and date handwritten) next to or underneath your whole plant, including the roots, stem, leaves, and flower(s). Make sure that you can see the paper with name and date AND the whole plant in the picture. You will need to upload this picture to the Canvas Quiz for this lab assignment.

2. Examine the root system of your flowering plant. Does your plant have a fibrous root or taproot? You will need to indicate this in your Canvas Quiz for this lab assignment.

3. Examine the veins in the leaf of your flowering plant. Are the leaf veins parallel or in a branched network? Based on this, is your plant a monocot or dicot? You will need to indicate this in your Canvas Quiz for this lab assignment.

Part 2B: Dissecting the Plant: Root or Stem *BE CAREFUL WHEN USING A KNIFE*

4. Using your knife, carefully cut a very thin cross-section slice of either the root or stem of your flowering plant. Hold the cross-section slice up to the light (you may stick it on a window or shine a flashlight behind it). Using your text book, other books, or websites, identify the vascular tissue (xylem and phloem in bundles), ground tissue, and dermal tissue in this cross section. (It may help to sketch or photograph your cross section). You do not need to upload an image of this cross section. Instead, you will be required to identify these 3 tissues in a picture of a carrot root in the Canvas lab quiz.

Part 2C: Dissecting the Flower *BE CAREFUL WHEN USING A KNIFE*

The flower parts are arranged in whorls atop a swollen stem tip, the receptacle. The outermost whorl is frequently green (although not always) and is the calyx. Individual components of the calyx are called sepals. The calyx surrounds the rest of the flower in the bud stage. Moving inward, locate the next whorl of the flower, the colorful corolla made up of petals.

The next whorl of flower parts consists of the male pollen-producing parts, the stamens. Examine a single stamen in greater detail. Each stamen consists of a stalk-like filament and an anther. The anther consists of four microsporangia (also called pollen sacs).

Next locate the female portion of the flower, the carpel. At the top of the carpel is the stigma, which serves as a receptive region on with pollen is deposited; a neck-like style; and a swollen ovary. Note that the only members of the plant kingdom to have ovaries are angiosperms. Inside the ovary are ovules in which the eggs develop. After fertilization, the ovules develop into seeds, and the ovary enlarges and matures into the fruit surrounding the seed.

*BE CAREFUL WHEN USING A KNIFE*

5. Obtain one flower of your flowering plant and remove the sepals and petals from one side. Using your knife, carefully make a longitudinal cut in the ovary to observe the ovules inside of it.

6. Prepare another blank sheet of paper and write your name (First and last) and the date on the top of the paper.

7. Place your dissected flower on the sheet of paper (not blocking the name and date) and label the following parts with arrows using your text book, other books, or websites. You will need to photograph this labeled flower on your paper upload this picture to the Canvas Quiz for this lab assignment. Parts to label:

· receptacle

· calyx (many sepals)

· corolla (many petals)

· stamen (filament and anther)

· filament

· anther

· carpel (stigma, style, and ovary)

· stigma

· style

· ovary

· ovules

8. Take a photo of your labeled flower on paper (with name and date handwritten, dissected flower, and labels indicated in step 7 above). Make sure that you can see the paper with name and date AND the whole labeled flower in the picture. You will need to photograph this labeled flower on your paper upload this picture to the Canvas Quiz for this lab assignment.

Before you complete the Canvas Quiz for Lab 10, double check your two picture files:

· Make sure that they are in .png, .jpg, or .pdf format.

· Apple/iPhone/MAC users, make sure to convert any .HEIC files to one of the accepted formats.

· Make sure that your handwritten name (first and last) and date are visible in each image file!

· Make sure that you have included all required labels and plant parts in your images.

Your handwritten name and date need to be in BOTH pictures in the file in order for you to be eligible to earn credit for them.

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