Name______

Lab: Fruit Types and Classification of Fruits

What is a fruit? Botanically speaking, a fruit is a ripened ovary with seeds and any other structures that enclose it at maturity. This definition of a fruit means that many ‘vegetables’ are fruits (squash, tomatoes, beans, corn) and many ‘grains’ are also fruit (rice, wheat, etc.).

Remember that the ovary is part of the pistil, or female part of the flower. When pollen from the stamen reaches the pistil and travels down the style into the ovary, it can fertilize ovules and the seeds and fruit begin to develop.

While the seeds develop from the ovules, the ovary tissue undergoes a series of complex changes that results in the development of the fruit. As the ovary develops into a fruit, its wall often thickens and develops three layers:

· Exocarp- the outermost layer (often like a skin or peel). · Mesocarp- the middle layer (often fleshy), varies in thickness · Endocarp- the innermost layer (often hard, stony or papery)

Together, these layers are called the pericarp. These layers are most visible in “fleshy” fruits:

In this lab, you will learn about several common fruit types.

I. Fleshy fruits.

A. Drupe. A fleshy fruit formed from one ovary with a single stony seed. Examine the Avocado and answer the following questions:

What part of the ovary wall is the rough skin of the avocado?

What part of the ovary wall forms the fleshy part that we eat?

What part of the fruit forms the stone or pit?

Name another common drupe that we eat.

B. Berry. A fleshy fruit formed from 1 ovary with few to many seeds. Make a sketch of either the tomato, eggplant, or green pepper. Be sure to draw and label the following: pedicel, sepals, style.

Where were the petals and stamens attached?

Examine the cross-section of the fruit you drew above. How many chambers or locules does it have?

II. Dry dehiscent fruit. Dehiscent means that it splits open when mature.

A. Legume. These may be somewhat fleshy when young, but become dry when mature. Examine the bean or pea pod on your table and answer the following questions as you observe the fruit.

At which end of the pod were the stamens, petals and sepals attached? Is there any evidence of these parts?

Split the pod lengthwise along both edges. Do all the seeds adhere to one side, or do they alternate from one side to the other?

Legumes are very common in the Sonoran Desert. Think about the vegetation around Tucson and name a common tree or shrub that has a similar fruit and is a legume.

III. Dry indehiscent fruit. These do not split open.

Use the key below to identify which type of dry indehiscent fruit the following are and write the fruit type in the blanK: a. sunflower seed ______b. corn ______c. maple seed ______d. walnut ______

1. Fruit winged……………………………………………………..(Samara) 1. Fruit not winged………………………………………………………....(2) 2. Ovary wall tough and hard……………………………………..….(Nut) 2. Ovary wall not especially tough and hard………………………….....(3) 3. Seed attached to ovary wall at only one point……………..(Achene) 3. Seed attached to ovary wall at all points…………...…...(Caryopsis)

Look for a tiny bump on the upper end of the corn grain marking the location where the silk was attached. What is the silk of corn?

How many flowers does it take to make up a cob of corn? One or many?