Title: Assignment: LAB: Seed plants
Course: BIO-182 RTZ

Include all diagrams and answers to questions for this lab in your portfolio. I will collect them next Tuesday, when I return to class. There is nothing to submit at this time.

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SEED PLANTS

General Objectives:

- Relate the structure of seed plants to their functions in the land environment
- Identify various types of fruits, recognize examples and describe dispersal mechanisms.
- Describe features of flowers that ensure pollination by insects, birds, bats, and wind.
- Describe the life cycle of a gymnosperm and angiosperm

PARTS of a FLOWER

Objectives: to study the structure of a typical flower.

- Obtain a single flower and observe its parts carefully.
  - Flower parts are arranged in a circular pattern.  Each circle is called a whorl.  The whorls are  attached at the enlarged receptacle located at the base of the flower.

Read this section before you begin your dissection:

As you examine your flower, you will be carefully removing parts beginning with the outer whorl and working your way in towards the pistil.  Rather than sketch each part, today you will arrange each whorl in a circle on a sheet of paper paper, beginning with the sepals as the largest outermost circle.  As you proceed with your dissection, you will carefully tape each whorl of flower parts into position and label them.  As each whorl is observed and removed, add the appropriate information to the page (observations and function).

1. The sepals form the outermost whorl of the flower.  The sepals are leaf-like structures that are usually     green in color.  Sometimes, the sepals are the same color as the petals, or appear to be another set of petals of a different color.  The function of the sepals is to protect the inner part of the flower before it blossoms.  Gently remove the sepals, tape them into position onto the paper, and label them. Record the following observations:

a)     How many sepals does your flower have?

b)     Describe the appearance of the sepals (color, markings, etc.).

1. The petals are found directly under the sepals.  The color and odor of the petals help to attract birds and insects to the flower for pollination.  Gently remove the petals, tape them into position onto the paper, and label them.   Record the following observations:

a)     How many petals does your flower have?

b)     Describe the appearance of the petals (color, markings, etc.).

1. The stalk-like structures inside the petals are the stamens, the male reproductive organs.  Depending on the species, the stamens may be attached to the receptacle, to the petals, or to the pistil.  The enlarged portion at the top of the stamen is the anther.  Inside the anther are pollen sacs, which produce pollen grains.  When the pollen grains mature, the pollen sacs split open, releasing the dust like pollen grains. The filament is the thin structure that supports the anther.  Gently remove the stamens, tape them into position onto the paper, and label them.  Record the following observations:

a)     How many stamens does your flower have?

b)     To which structure(s) were the filaments attached?

c)      Have the pollen sacs opened?  How can you tell?

d)     If pollen grains are visible, describe their appearance.

1. The central structure of the flower is the female reproductive organ, the pistil.   The top of the pistil is the stigma.  When mature the stigma is enlarged, and its surface is moist and sticky.  The style is the middle portion of the pistil.  It supports the sigma.  Some flowers lack a style.  The ovary is the enlarged structure at the bottom of the pistil.  The ovary contains one or more hollow compartments known as locules.  The locules contain ovules, which in turn, contain the egg nuclei.

Carefully remove the pistil by cutting it from the stem just under the ovary.  Using pencil, make a life-sized sketch of the entire pistil (just the outline) in the center of the plain paper and label it.  Cut the style just at the top of the ovary, tape it next to your sketch, and label the stigma and style.  Using the ruler, measure the length of the style in millimeters.  Cut a thin cross-wise section of the ovary and tape it under the stigma and style.  Label the ovary wall, locules and ovules.   Using the dissecting needle, carefully pick the ovules out of one of the locules.  Try to estimate how many ovules are contained in one locule.  Record the following observations:

a)     What color is the pistil?

b)     Describe the appearance of the stigma.  Is the stigma mature?  How can you tell?

c)      How long is the style (in mm)?

d)     Describe the appearance of the ovary.

e)     How many locules does the ovary contain?

f)      Approximately how many ovules are contained in one locule?

PARTS of A SEED

Objectives: to study the structure of a typical seed.

- Sketch the outside of the lima bean.  Identify the following parts: hilum, micropyle.  State their function/ what are they?

- Use your fingernail to carefully peel off the thin outer covering or seed coat from a

soaked lima bean. Split the seed in half, sketch and label the parts listed below.

- Embryo
- Plumule (future leaves)
- Stem
- Radicle (future root)
- Cotyledon (stored food)
- Seed coat (protective covering)

QUESTIONS:

- What is the function of the seed coat and the cotyledon?
- Why is it important that all seeds have a supply of stored food?

FRUIT

Objectives: to study the structure of various fruits.

1. Read the following:

- Fleshy fruit.  A fleshy fruit consists of a single ripened ovary with a soft, fleshy ovary wall when ripe. Three kinds of fleshy fruits are the drupe, pome, and the berry.
  - The peach is a drupe. The exocarp is the covering or skin. The mesocarp is fleshy. The endocarp is hard and encloses the seed.
  - The apple is a pome. The stem is the stalk by which the flower was attached. At

the other end are the remains of the sepals, petals, and a ring of dried stamens.

The thin skin is the epidermis. The fleshy part inside the skin developed from the

receptacle, or flower stalk. The papery core is the ovary wall. Within the ovary are

the seeds.

- The grape is a berry. The entire ovary is soft.

- Dry fruits have an ovary wall that is dry and brittle when ripe. They are classified as dehiscent or indehiscent. A dehiscent fruit splits along a definite seam when ripe. The bean is a dehiscent fruit called a legume. It splits along two seams.

- Use an iPad to find labeled diagrams of the following fruit: Peach, apple, grape and bean pod. Look for the  following parts on those diagrams: Exocarp, Mesocarp, Endocarp, Seed, Ovary wall, Epidermis,  Receptacle.

2. Examine each of the fruits listed in the table below and determine if they are fleshy or dry. Determine the type of fruit (drupe, pome, or berry; dehiscent or indehiscent). Record your answers in the table.

FRUIT | FLESHY or DRY | TYPE
Plum |  |
Tomato |  |
Apple |  |
Okra |  |
Olive |  |
Pea Pods |  |
Avocado |  |
Corn |  |
Bean |  |
Sunflower |  |

3. Sketch at least three of the fruits available.  Label the following on your sketches:  type of fruit, seed, ovary or ovary wall, and where appropriate,  endocarp, mesocarp, and exocarp.

QUESTIONS:

1. What part of the flower becomes the fruit?
2. What part of the flower becomes the seed?