--> WEDNESDAY 1. Lecture cancelled - see Friday Ecology

Seminar instead: 4 - 5 pm NULH (possible extra credit available)

2. Lab review 2 - 4:30 pm3. Term papers returned

--> MONDAY - Lecture Midterm and Lab Practicum

1. Study Guide available on web site Tuesday Afternoon

Announcements

Correspondence between flower and fruit

http://w3.dwm.ks.edu.tw/bio/activelearner/35/images/ch35summary.gif

Forming a Seed

1. Fertilization - initiates both seed and fruit development

2. Seeds develop from ovules

3. Driest living plant tissue (<20% H20)

4. Seed coat - resistant and buoyant

Seed Parts

1. Embryo - grows into sporophyte

2. Integuments (seed coat) - protection

3. Endosperm - food reserve

Options for Food Storage in Seed

A. Endosperm• Fusion product of two polar nuclei in ovule• Grows by nuclear division while embryo is dormant• Often 3N tissue• Ranges from solid material to liquid

B. Fleshy seed leaves

C. None

Fruit - Seed Protection and Dispersal

1. Develops from ovary tissue

2. Associated extra- carpellary structures (petals, sepals)

3. Fruit wall of ovary4. Surrounds and

protects the seed(s)

5. Important in seed dispersal

6. Initial nutrient source

Types of Fruits

1. Fleshy - attract animal dispersers move seeds to new locations after successfully passing through the digestive system of the animal

2. Non-fleshy - other mechanisms for seed dispersal

3. Parthenocarp - fruits developed without fertilization (typically seedless)

Fruit Layers

1. Ovary wall often thickens - Pericarp

2. May be differentiated into three, more or less distinct, layers • Exocarp - outermost layer; often epidermis

• Mesocarp - middle layer; varies in thickness • Endocarp - inner most layer; considerable variation from one species to another

Classifying Fruits

1. Depends on number of ovaries and the number of flowers involved formation

2. Classified into three major groups – Simple - from single mature ovary in a single flower– Aggregate - many matured ovaries from a single

flower– Multiple - matured ovaries of several flowers united

into a mass

http://www.fao.org/DOCREP/005/Y2515E/y2515e04.htm

Figure 3.1: Plant tissue consumed as fruit.(Coombe, 1976; Kays, 1991)

Types of Simple Fruits

A. Simple Fruits - can be fleshy or dry (nonfleshy)

B. Nonfleshy fruits can beA. Dehiscent - split open

when fully mature

B. Indehiscent - do not split open when mature

Simple Fleshy Fruits

1. BERRY - layers of pericarp fused; lots of seeds

1a. Pepo - hard rind (exocarp); only in Cucurbitaceae (e.g., squash)

1b. Hesperidium - leathery exocarp rind with oil glands (Citrus); mesocarp white parenchyma tissue; endocarp multicellular juice sac hairs

2. DRUPE - stone fruit, derived from a single carpel and containing (usually) one seed

Coconut - a specialized drupe

Simple Fleshy Fruits, continued

3. POME - Rose family only; from several carpels; also example of an assessory fruit due to tissues besides carpel

3a. HIP (accessory fruit)- several separate carpels enclosed within the fleshy or semi-fleshy receptacle

Dry Fruits - pericarp dry

at maturity

DEHISCENT

1. FOLLICLE - one carpel; pod-like fruit splits along single suture

2. LEGUME - one carpel; splitting along two sutures

3. CAPSULE - several carpels; can split along various sutures

4. SCHIZOCARP - fruit splits into 1-seeded segments, but carpel does not split open

Dry Fruits - Dehiscent

continued

Dry Fruits - do not

split at maturity

INDEHISCENT

1. ACHENE - one-seeded fruit; seed attached to pericarp at one point only

2. CARYOPSIS - grain; one-seeded fruit; attached to pericarp at all possible points

Dry Fruits -

INDEHISCENT continued

3. SAMARA - one- or two-seeded fruit; pericarp bearing a wing like outgrowth (modified achene)

4. NUT - hard, one-seeded fruit; generally from compound ovary; with the pericarp hard throughout

Aggregate Fruits

1. A fruit derived from a single flower with many pistils resulting in. many matured ovaries formed in a single flower

2. Each "Fruitlet" is the product of one carpel.

3. Individual ovaries called fruitlets.

4. Hard to distinguish between multiple and aggregate fruit without knowledge of the flower.

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Multiple Fruits

1. Fruit derived from several or multiple flowers clustered along a common axis.

2. Typically are accessory fruits

Accessory Fruits

1. Develop from tissues surrounding the ovary

2. Generally develop from flowers that have inferior ovaries

3. Receptacle or hypanthium becomes a part of the fruit

4. Accessory fruits can be simple, aggregate or multiple