Integrative Biology 335:
Systematics of Plants

Fruits and Inflorescences

Announcements:

Laboratory Four will also introduce you to fruit and inflorescence terminology.

Your first take-home lecture assignment, worth up to 2% of your final grade, is due in class on Wednesday, February 11th. This assignment was distributed in lecture on Wednesday, Feb. 4th. Penalties will be assessed for assignments handed in late (i.e., after class); assignments more than 24 hours late will not be graded. Answers will be posted on the web immediately after lecture the day the assignment is due. Graded assignments will be returned to you in lab.

Text and Other Resources:

Plant Systematics, A Phylogenetic Approach, Third Edition, Inflorescences, Fruits, and Seeds by Walter S. Judd et al.

Digital Flowers. Once in the program, access Morphology: Fruits and Morphology: Inflorescences.

Botany at the Grocery Store, a web project prepared by Britt Wilms, a previous IB 335 student.

Other Web Resources: Please note: The links provided in this syllabus lead to supplementary information offered by other on-line systematic courses at other universities or sources. Please use with caution, as some of the information presented may be different from what we cover in this class.

General objectives:

After studying this material you should be able to:

  1. Know the difference between fruits and vegetables and how to define a fruit botanically.

  2. Explain what part of a flower matures into what part of the fruit.

  3. Describe, illustrate, compare, and contrast the various types of fruit, including the special fruit types.

  4. Know the parts, positions, and various types of indeterminate and determinate inflorescences.

What is a fruit? What is a vegetable?

The term fruit originally meant any plant used as food. In the 18th century, as the science of botany arose, the word was given a more precise, technical meaning.

The word "fruit" has different meanings to different people. To the layperson, it carries the connotation of a sweet, soft plant product. Thus, it is usually regarded as a dessert food. Vegetables are usually a savory or maincourse food. They can actually represent leaves, tubers, roots, and even entire inflorescences! Botanically defined, not all fruits are soft and sweet and many are not good to eat at all!

Fruits are distinguished from vegetables in other ways too. We often refer to fruits when we want to convey praise and, in contrast, we often refer to other plant products when we want to insult.

First, the praise ...

Now, the insults ...

Fruits are also implicated with pleasure, for as children we are always told to eat our vegetables whereas the fruits always tasted much better!

Actually, fruits generally have a much higher sugar content and are often more acidic than those things we call vegetables. Remember the Ancient Greeks? Since their time, fruits have been eaten at the end of the meal and not with the meal.

Did you know that in the 1930's, the US Supreme Court ruled that a tomato was legally a vegetable rather than a fruit? It's true! A New York food importer had claimed duty-free status for a shipment of tomatoes from the West Indies. He argued that tomatoes were fruits, and so under the regulations of the time, not subject to import fees. He must have taken this class! The customs agent disagreed and imposed a 10% duty on the shipment he defined as vegetables. The Supreme Court decided on the grounds of custom. Because tomatoes are "usually served at dinner in, with, or after the soup, fish, or meat, which constitute the principal part of the meal, and not, like fruits, generally as dessert." So, a tomato was ruled as a vegetable!

Incidently, President Ronald Regan once said that ketchup was also a vegetable!

So, what actually is a fruit?

A fruit is a ripened ovary (=a mature ovary) of a flower along with any adnate parts.

What is a seed?

A seed is a baby in a box with its lunch.

Specifically, it is a ripened (fertilized) ovule containing an embryo within a seed coat (protective covering), and often has additional storage tissues (food reserves).

FLOWER FRUIT
ovary fruit
ovary wall pericarp (the fruit wall)
ovule seed
integuments seed coat
zygote embryo
fusion nucleus endosperm
funiculus seed stalk

Remember! The egg and one sperm nucleus fuse to form the zygote (which develops into the embryo). The two polar nuclei in the ovule and a second sperm nucleus unite to form the fusion nucleus (which will eventually mature into the endosperm).

If you wish to review the angiosperm life cycle, see your textbook (Fig. 4.17, p. 63) or try these links:
University of Maryland
University of Manitoba

Classification of fruits

Fruits can be divided into several groups based on various criteria:

Are these true fruits (in the botanical sense)?

apple
banana
carrot
green bean
eggplant
avocado
squash
corn
potato
tomato
cucumber
artichoke
peanut
coconut
onion
water chestnut
lettuce
celery

Fruit types based on morphology

DRY FRUIT TYPES

FLESHY FRUIT TYPES

Fruit types based on taxonomy

We will consider each of these fruit types in more detail when we study these families or subfamilies.

Special fruit types

Finally, a child's view of the major fruit types

What is an inflorescence?

An inflorescence is simply the arrangment of flowers on a floral axis. A cluster of flowers, basically.

Parts of an Inflorescence

Positions of Inflorescences

Sequence of Flowering and Types of Inflorescences

Other Inflorescence Types (that we'll cover later)

If you find this subject matter confusing...

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