sign in sign up
<<
Home , Gynoecium, Locule, Placentation

Anatomy of a – most have four types of structures, all of which are modified

Lecture 24.

Flowers (cont’d)

Topics Androecium = collection of

• 1. Male part: Androecium • = anther + filament. • 2. part: • Anther produces • 3. Coalescence VS Adnation (Microgametophyte) • 4. Types of flowers – Insertion of floral structure • Superior: hypogynous and perigynous • Inferior: epigynous – Flower Symmetry Long section through a mature flower. – Complete/Perfect Flowers – Monoecious/Dioecious Flowers

Gynoecium = collection of carpels How are attached in

• Carpel = + style + (containing ovules) carpel – concept of • Æ •Carpel Æ

Ranunculus

1 Types of Placentation Marginal Placentation

• The is the area of the Carpel • This Diagram is to which Ovules are attached. similar to the single Carpel of a – Marginal Placentation Gynoecium. – Parietal Placentation • Transparent Model – Axile Placentation of a Legume Carpel – Central Placentation with Marginal Placentation

Marginal Marginal Placentation Placentation • Legume have • Cross Section of a their Ovules attached Legume Carpel showing along the area where the Ovule and Pericarp the Marginal Traces • Cross Section of a Legume Carpel showing occur. the Vascular Bundles • Cross Section of a Legume Carpel showing the location of the Placenta

Parietal Placentation Parietal Placentation

• Two or more • Cross Section through an Ovary with Parietal Carpels are fused at Placentation their Margins such • Wild Cucumber with Parietal Placentation: The Placental that a Single areas have enlarged and is created, the create the illusion of a partitioned locule. Placentae are generally located at the Sutures. This is called Parietal. Model of A Syncarpous Gynoecium with Parietal Placentation.

2 Parietal Placentation Axile Placentation

• Passion Flower sp. • Axile Placentation occurs • Passion Fruit when the Ovules of a • Cross Section of an Immature Passion fruit Syncarpous Gynoecium • Cross Section of an older Passion fruit are attached to a Central Axial Structure and the Ovary is divided into two or more chambers ().

Cross Section of a Lily Ovary which has Axial Placentation with 3 Carpels & 3 Locules.

Axile Placentation Central Placentation

• Central Placentation is similar to Axile except that there is only One Locule. The Ovules are attached to a central pilar of but there is only one Locule.

Central Placentation Example -

• Cross Sections of an Ovary with Central • Species of Magnolia can have many Placentation , Stamens & Carpels. The Gynoecium is Apocarpus like Ranunculus.

3 Mature Example – Magnolia Flower Example - Magnolia • Note the many Carpels at • Immature (Green) and Mature Carpels (Peach) in the apex of the . Magnolia. • Immature Androecium & Gynoecium • Mature Androecium & Gynoecium

Immature

Example - Magnolia Carpel • 1. After Fertilization. Each Carpel contains a single Seed in its Ovary. •2. Magnolia Carpels: The Carpels become Fruits. •3. Magnolia Mature Carpels: The Fruit is a Dry Dehiscent . The have a red, fleshy outer Seed Coat.

1 23 Anatomy of Male/Female flowers

Citrus Flowers Citrus • Long Section through the • Female: Syncarpous Base of a Citrus Flower. Gynoecium. • Long Section of a Citrus – Note the large, lobed Flower showing the Stigma, Style and Anthers appearance of the Stigma. This • Cross Section through a indicates that the Gynoecium Citrus Flower at the Level is probably Syncarpous. of the Style Can you find Coalescence in any other floral organs?

Enlargement of style, see next slide

4 Citrus Citrus • Cross Section of the Ovary with • 1. Enlargement of the Style from the Lines defining the Carpels. previous slide. Count the Number of Note the 10-11 Vascular Bundles!!! Carpels!!!!! • 2. Cross Section of a Citrus Flower • Cross Section of a Citrus Fruit at the Level of the Ovary with the Carpels labeled. • 3. Cross Section of the Ovary 3 Count the Number of Carpels!! showing the Ovules and the locules • the number of Vascular Bundles (L). Count the Number of in the Style equalled Locules!!!! the number of Carpels in the Ovary which equalled the number of Carpels in the Fruit. • Consequently, the Gynoecium contained 10 Carpels and was Syncarpous!!!!

1 2

The number of Stigmatic Lobes can signify the Cross Sections from a lily flower which is Syncarpous number of Carpels. • The yellow lines • Note the number of indicate the Stigmas on this Hibiscus. boundries of each • The Stigmas are fused at carpel & a lower level. How many the numbers signify carpels are involved? the individual carpels.

Seed Development • Seed: Mature ovule that contains an , with stored food enclosed in a protective coat. • Seed development: Complete & Perfect Flowers – After , nucleus begins to divide asymmetrically, forming endosperm tissue. – divides • Small cell is destined to become the embryo. • Larger cell divides repeatedly to become a suspensor. • Complete - Has all four floral Organs • Incomplete - One or more floral organs missing • Perfect - Flower with Androecium & Gynoecium • Imperfect - Missing Androecium or Gynoecium • Carpellate Flower - Imperfect flower that has only Carpels • Staminate Flower - Imperfect flower that has only Stamens

5 Flowers Monoecious vs. Dioecious

• Begonia with • Monoecious (One Staminate Flowers House) -One has BOTH Cucurbit with Carpellate Flowers • Begonia with Carpellate & Carpellate Flowers Staminate Flowers. • Dioecious (Two Houses) -One plant has only Staminate Flowers & another plant has only Carpellate Flowers

Cucurbit with Staminate Flowers

6