13.4: Flower Dissection
- Page ID
- 133702
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)In the previous exercise, we learned about the flower-producing plants – the angiosperms. Flowers serve as an important evolutionary development in plants and have created situations where plants utilize the services of other organisms to help with pollen and seed dispersal. Generally, the pollinator must be “rewarded” to entice them to return to the flowers. This reward generally is given in the form of nectar which is a sweet, nutritious substance eaten by the pollinators. Other flowers rely on trickery to fool a pollinator into accidentally pollinating it. Many of these pollinators have developed a very special relationship with a single flower type or species. This development is called coevolution – where two species evolve in response to each other – and can lead to changes in both the pollinator and the plant. Below is a table discussing some of the additional ways plants try to attract certain pollinators.
| Flower Trait | Type of Pollinator it Attracts |
|---|---|
| Open during the day | Pollinators that are awake in the daytime |
| Open at night | Pollinators that are awake at night |
| Red or orange color | Birds who see reds easily |
| Yellow, blue, or UV color | Bees and butterflies who see these colors and UV light |
| White color | Bats who see the bright white flowers at night |
| Flowers smell sweet | Bees, butterflies and bats who have good sense of smell |
| Flowers smell rotten | Flies who are attracted to rotting meat |
| Tubular shaped flowers | Butterflies and hummingbirds who have long tongues |
| Large flowers | Bats and other large animals that are heavier than other pollinators |
Some flowering plants bypass using animals as pollinators completely, using wind to carry pollen and small, light seeds. You’ve likely seen this before in the form of dandelions, who’s seeds take on a “puffball” appearance before being scattered by the wind (or a person who decided to blow on it!)
Now let’s get more familiar with the flowers by revealing their important structures through dissection. In the table and image below are some of the important parts seen in flowers. After we familiarize ourselves with these, we will dissect some flowers to see these structures in their various forms.
| Flower Part | Purpose |
|---|---|
| Pistil | The female reproductive part that receives pollen and produces the ovule |
| Stamen | The male reproductive part that produces pollen for dispersal |
| Petal | Serves as the visual aid to attract pollinators |
| Sepal | Protects the flower while it is developing and opens to let the flower bloom |
| Ovule | Forms the seeds that develop after the flower is pollinated |
| Receptacle | A supportive structure to handle the weight of the flower and/or fruit |
Anjubaba, CC BY-SA 4.0 , via Wikimedia Commons
Now let’s examine the flowers. Before we dissect them, let’s examine their outer appearance. We will write down information about each flower in the table provided as well as create a drawing for each.
| Trait | Drawing | ||
|---|---|---|---|
| Flower #1 | Color | ||
| Scent | |||
| Flower Shape | |||
| Flower Size | |||
| Potential Pollinator(s) | |||
| Trait | Drawing | ||
|---|---|---|---|
| Flower #2 | Color | ||
| Scent | |||
| Flower Shape | |||
| Flower Size | |||
| Potential Pollinator(s) | |||
| Trait | Drawing | ||
|---|---|---|---|
| Flower #3 | Color | ||
| Scent | |||
| Flower Shape | |||
| Flower Size | |||
| Potential Pollinator(s) |
After you have examined each flower’s exterior, you are ready to dissect it. You should make one cut along the long axis of the flower, dividing it into mirror-image halves. Be sure the cut goes through the middle of the flower, bisecting the ovary and receptacle. Dissecting microscopes will be available in the lab to help you make clean and even cuts through the middle of the flower. If you find yourself having trouble, ask your instructor for help.
Use caution when using sharp objects such as scalpels to avoid cuts. If your blade is too dull, ask your instructor for a new one.
After you cut the flowers open, observe the inside structures that you couldn’t see before. In the space below, draw each flower and include labels for the following:
- Anther (part of stamen)
- Stigma (part of pistil)
- Ovary (part of pistil)
- Petals
- Sepals
- Receptacle
Lastly, prepare a wet mount of the ovary and anther from your flower to observe ovules and pollen. Place a drop of water on a slide. Using a scalpel, slice a thin cross section of the ovary or anther and place the thin slice in the water on the slide. Apply a coverslip. Using a compound microscope, view the wet mount under 4x, 10x and 40x. Sketch what you see and make notes on the structure of each.
Flower #1
Flower #2
Flower #3
*Modified by Karen Marks, adapted from "Pollination Lab" by Rachel Cohen and Ralph Tingley, Michigan State University is licensed under CC BY-NC 4.0