FRUIT LAB

INTRODUCTION:

The goal of this laboratory is to introduce you to the wonderful world of fruits. In the flower lab, we observed thatthe ovary, style, and stigma make up the pistil, and that the ovary is a protective vessel in which ovules are nourished to theirmature form--seeds. Recall that the closed carpel evolved via infolding of the leaf to form an enclosed vessel. Each of thesevessel units is a carpel with its own line of placentation or zone of ovule/seed attachment. The fruit provides protection andfacilitates dispersal of the seeds. Ovaries and fruits can be composed of one to many free or fused carpels. The number ofovules associated with each carpel, and thus the number associated with the ovary, can vary from one to many. Also, ovariescan be separated into several distinct chambers or consist of only one chamber. These chambers are called locules. Thenumber of locules is often (but not always) equal to the number of carpels. Remember to check the number of placentae,too.

Dispersal of seeds in nature is accomplished in many ways. Seeds can be dispersed by animals, wind, water, etc.Animal dispersers range from insects to birds to mammals to fish. Modifications in the shape, structure, and often color ofthe ovary directly correspond to the ways in which seeds are dispersed. Bright red, fleshy berries are commonly dispersedby fruit-eating birds. Winged fruits, such as those found on maple trees, have obviously come about through modificationswhich facilitate wind dispersal. How might nuts, such as acorns, be dispersed? What animals have you observed eating andburying acorns in the autumn? What characters would a water-dispersed fruit have?

By the end of this laboratory exercise you should be able to recognize the various fruit types which are present innature and understand the similarities and differences between these fruit types. You should become familiar withthe terminology used to describe fruits, such as carpel, ovule, zones of placentation, etc. You should be able to countthe number of carpels present in a given fruit and to recognize the arrangement of these carpels within the ovary—theplacentation type. Lastly, and most importantly, you should be able to recognize by name (common, scientific, and/orfamily name) the fruits displayed. You should leave the laboratory with a deeper appreciation for the fruits of the floweringplant world and-- a stomach full of these incredibly delicious props!

I. Fruits essential for human survival:

1. LEGUME: Single carpel, multi-seeded, dehiscent along two sutures (wild types), seed consists mostly of young embryosporophyte (high protein):

Peanut - geocarpic, pericarp, testa, cotyledons (high protein - endosperm converted to embryo - true of mostFABACEAE [Leguminosae].

Green Bean - single line of ovules (nearly mature)

Snow Pea - ovules and fruit, less mature

2. CARYOPSIS: More than one carpel BUT only a single seed. Seed, mostly endosperm (high in starch) The seedcoat isfused to the pericarp

Corn (maize) - FRUIT is a CARYOPSIS, but the EAR is a MULTIPLE fruit [fruits from separate flowers of a singleINFLORESCENCE combined in a single structure. Note inflorescence stalk [RACHIS] or corncob.

Other true grains--rice, wheat, oats, rye, barley, sorghum.

II. Other fruits and fruit-like structures:

3. ACHENE: More than one carpel, one seed, pericarp a single layer of tissue and SEPARATED from the seed. TheCARYOPSIS [fruit of the grass family - POACEAE] is similar in structure BUT pericarp and seed are united.

Sunflower - Fruit [for the birds] and seed [for people]

Strawberry - FRUIT is a tiny achene (many positioned in 'pits' that occur in the expanded, red, sweet RECEPTACLEof the 'AGGREGATE FRUIT' [a 'false' fruit]

4. NUT : a dry, indehiscent, 1-seeded fruit with a hard exocarp. The ovaries that produce nuts have more than one carpel,but through abortion, only one seed matures.

Pecan - edible portion is embryo and cotyledons

5. CAPSULE : a dry, dehiscent fruit made up of several carpels. The ripe pericarp splits open along pores or slits.

Okra - capsule eaten while green

6. DRUPE: Single carpel, single-seeded, pericarp tissue differentiated into THREE layers: EXOCARP, MESOCARP,ENDOCARP:

Peach - exocarp with fuzz; Nectarine, plum, and cherry - exocarp without fuzz

Almond - exocarp/mesocarp removed, just PYRENE [=endocarp and seed]

Avocado - endocarp VERY thin

Coconut - mesocarp fibrous ,[dispersal], testa thin, endosperm both solid [meat] and liquid [milk]

Raspberry - an AGGREGATE (separate ovaries of one flower joined together) of small drupes [druplets]

7. BERRY: More than one carpel, fleshy [animal dispersed] and many-seeded.

Tomato- two carpels/locules - primitive, more derived forms have extra septa and locules

Peppers - midway between a CAPSULE [dry, dehiscent] and a berry

Eggplant - selected for extra tissue - no locules

Kiwi fruit - leathery, fuzzy pericarp with many carpels, seeds attached on a central mass of white tissue

Banana - epigynous - 'peel' is a combination of pericarp and HYPANTHIUM - a sterile polyploid, ovules are aborted

Blueberry - epigynous

Grapes - clustered in panicles

8. PEPO: a 'special' BERRY from an epigynous flower of the CUCURBITACEAE - leathery or hard 'rind' (Pericarp +hypanthium), 1 locule, and 3 lines of ovules.

Cucurbita - summer' squash vs. 'winter' squash [pumpkin]

Cucumber - entire fruit is consumed

Watermelon - 90% water

Honeydew, cantaloupe, musk melons - all one species

9. HESPERIDIUM: a special type of berry with numerous carpels (separable as 'sections'); locules filled by plump cells(which are modified hairs!); pericarp with oil glands. Fruit produced by the genus Citrus.

Orange, lemon, lime, grapefruit - distinctive essential oils

10. POME: a 'false fruit' that is formed by fusion of the HYPANTHIUM (of an epigynous flower) to the ovary, with thehypanthium forming the edible portion.

Apple/Pear - note sepals on the opposite side from the pedicel (the flower is epigynynous) and internal demarcationbetween ovary wall and hypanthium.

11. AGGREGATE FRUIT: a multiparted fruit that develops from separate, simple pistils from ONE flower.

Blackberry/Raspberry--these are aggregations of tiny drupelets.

12. MULTIPLE FRUIT: a fruiting inflorescence with true fruits from separate flowers combined into a single unit(essentially a fruit-like infructescence). The maize ear is a unit formed from a pistillate inflorescence.

Pineapple - each perfect flower forms a berry, but they are compressed together to form the pineapple. Note that thecentral RACHIS of both pineapple and maize ear (cob) is a hard, fibrous, vascularized shoot (as opposed to pericarp) tissue.

Fig - inflorescence enclosed within receptacle tissue--this special fruit type is called a syconium

13. ACCESSORY FRUIT: a fruit in which the edible part is derived from something other than the ovary.

Strawberry--the real fruits are the little achenes (which most people call seeds) and the juicy red part we eat is anenlarged receptacle

Apple--Apples may be placed in this category, since the edible part is the hypanthium, not the ovary.

FRUIT LAB -- ACTIVITY

Carefully examine the fruits, paying special attention to their morphology, structure, family and scientific name, and geographic origin. During theexercise, answer the following questions for each fruit observed. 1. What is the fruit type? 2. How many carpels are present? 3. How might they might be dispersed in nature.

COMMON NAME GENUS & SPECIFIC EPITHET FAMILY CLASS FRUIT TYPE Carpel# ORIGIN

Almond

Apple

Avocado

Banana

plantain

Blueberry

Brazil Nut

Chayote

Cherimoya

Cherry

Chestnut

Coconut

Coffee

Cucumber

Date

Eggplant

Fig

Filbert/ Hazelnut

Grape

Grapefruit

Green Bean

Kiwano/ HornedMelon

Kiwi Fruit

Lemon

Lime and key lime

Long squash

Macadamia Nut

Maize (corn)

Mango

Melon

honeydew

cantaloupe/muskmelon

Okra

Orange

navelorange (seedless)

blood orange

Papaya

Passionfruit,Granadilla

Peach/Nectarine

Peanut

Pear

Pecan

Pepino "melon"

Pepper

bellpeppers of all colors

hot

Pineapple

Plum

"Pluot" plum-apricothybrid

Prickly Pear/Tuna

Pummelo

Raspberry /Blackberry

Snow Pea /Sweet Pea

Squash/Pumpkin

acorn squash

spaghetti squash

butternut squash

pumpkin

Yellow Crookneck

Zucchini

Star Fruit/ Carambola

Strawberry

Sunflower

Tamarillo

Tamarind/ Tamarindo

Tomatillo/ HuskTomato

Tomato

Walnut

Watermelon

QUESTIONS FOR THOUGHT, REVIEW, AND STUDY

1. What are two ways to count the number of carpels in a fruit?

2. Draw simple diagrams of various placentation types.

3. Draw a cross-section of a fruit which has 3 carpels, 1 locule, and parietal placentation.

4. Draw a cross-section of a fruit which has 3 carpels, 3 locules, and axile placentation.

5. Follicles and capsules are similar in that they both contain numerous seeds. How do these two fruit types differ?

6. What is meant by the word epigynous? Do epigynous flowers have inferior or superior ovaries?

7. What is a berry? List some examples.

8. What is a hesperidium? List some examples.

9. What is a pepo? How many carpels do pepos typically consist of? What family is characterized by the pepo?

10. Berries are usually sweet and many-seeded. Do you think these fruits are dispersed by wind or animals?

11. What is a samara? Give an example. How is it dispersed?

12. What is an aggregate fruit? List some examples.

13What is a multiple fruit? List some examples.

14. What is an accessory fruit? A strawberry is an example of an accessory fruit. What are we eating when we eat a strawberry?

15. What are we eating when we eat an apple? What type of fruit is an apple? How about a pear?

16. What is a drupe? Draw a cross-section of a drupe and label the parts. List some examples of fruits which are drupes. Whyare drupes often referred to as stone fruits?

17. The legume fruit type characterizes the bean family. Describe or define a legume; i.e., how many carpels are they composedof and how do they dehisce?

18. What is an achene? List some examples.

19. Why might apples be bright red and sweet in nature? Also, why might the native apples be much smaller than the apples nowcultivated by human beings?

20. What is your favorite fruit? What is the fruit type?

21. How many carpels are present in a cucumber? What is the fruit type?

22. What is an apricot?

23. Okra is in the cotton family, the Malvaceae. What type of fruit is okra? It has many seeds and is comprised of more than onecarpel. On that note, does okra originate from a simple or compound pistil? Is okra ripe when we eat it (are the seeds ready to bereleased)?