Chapter 39-Flowering Plant Reproduction

Composite Flowers

A type of inflorescence. These flowers have a floral head consisting of many small flowers. Ex] Sunflowers. The outer flowers that look like petals are sterile, incomplete ray flowers. The inner flowers are complete, very small disk flowers.

Pericarp

The wall of the ovary becomes this thickened wall of a fruit.

Male gametophyte in flowering plants

pollen grain

As seeds mature their water count is...

reduced.

Life cycle of a flowering plant

1. Haploid microspores produced in the anthers by meiosis develop into pollen, the immature male gametophyte. 2. Pollination occurs when a compatible pollen grain lands on a stigma. 3. Pollen tubes grow through the style to the ovary, in which are ovules that contain the haploid female gametophytes. 4. 2 Sperm cells fertilize the egg and a central cell in one ovule. The double fertilization produces a zygote from the egg and nutritive endosperm from the central cell. 5. Each ovule develops into a seed, and the ovary develops into the fruit. Fruit aids in seed dispersal. 6. A seed germinates and the embryo grows into a new sporophyte.

Asexual Reproduction

Common in plants. Fragmentation of many plants can produce new plants. Strawberries send out stolons (runners) that can form new plants. Black raspberries can start new plants with the tips of their shoots. Aspen clones can cover an entire mountainside. Some plants can produce seeds without pollination.

Aggregate Fruit

Develop from a single flower with many carpels. Ex] Blueberry, strawberry

Microsporocyte & Megasporocyte

Diploid

Bisexual (perfect flowers)

Flowers with a stamen and pistil. (both male and female parts)

Unisexual (imperfect flowers)

Flowers with missing stamens or pistil.

Multiple fruit

develop from an inflorescence (multiple flowers) Ex] Pineapple, fig

Double Fertilization

Angiosperms have these. One sperm nuclei fertilizes the egg forming a diploid zygote. The second sperm nuclei fertilizes the central cell forming a triploid nucleus that gives rise to the endosperm. Endosperm is the food storing tissue of the seed.

Carpellate flowers

Female flowers

Inflorescences

Flower clusters

Simple Fruit

Fruit derived from one ovary. The most common fruit. May be fleshy or dry. Many variations.

Microspores

Haploid, four of these are formed from a microsporocyte through meiosis.

Monocots' seed structure

Have a single, very thin cotyledon called a scutellum. The epicotyl is the embryonic shoot. The epicotyl is enclosed in a protective sheath called the coleoptile.

Complete flowers

Have all four flower parts--The sepals, petals, stamens, and pistil.

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Incomplete flowers

Lack one or more flower parts. Ex] Grass, missing petals and sepals.

Staminate flowers

Male flowers

Dormancy

Many seeds undergo this, a seed's metabolism is very low during this time. It can allow a seed to avoid germination until conditions are just right.

Pollination

Placement of pollen on the stigma of the carpel. Some flowers can self-pollinate. Most flowers are self-incompatible, they have physical and biochemical barriers to self-pollination.

Flower Type Dioecious

Plant species that have staminate and carpellate flowers on separate plants

Flower Type Monoecious

Plant species that have staminate and carpellate flowers on the same plant. Ex] Cattails and Corn

Fruit

Protects seeds and aids in seed dispersal. Develops from ovary of flowers.

Embryo

This is formed by a mitotic division of the zygote.

Development of seeds and fruit

The development of most fruit proceeds with the development of seeds. Seedless fruits develop from ovaries that have been stimulated by natural or synthetic growth hormones.

Development of female gametophyte

The embryo sac (female gametophyte) develops within the ovule. Gives rise to the embryo sac in a process that has many variations between species.

Hypocotyl

The point on the embryonic stem below the attachment of the cotyledons in Eudicots. The radicle is the embryonic root.

Accessory Fruits

These kinds of fruits, such as apples, develop their fleshy portions from flower parts at the base of the flower.

Eudicots' seed structure

They have fleshy cotyledons that store much of the food from the digested endosperm. Has a hypocotyl.

Germination

This depends on the absorption of water by seeds. It's the rehydrating with water causes the seed to swell and split open the seed coat. The growing seedling relies on it's own food storage until the foliage leaves are produced and photosynthesis can occur.

Where are pollen grains found?

Within the sporangium on the tip of the stamen. Consists of a tube cell and a generative cell that divides to form two sperm cells. Formed from a microspore through mitosis.

Female gametophyte in flowering plants

embryo sac

Seed coat

encloses the seed