Chapter 10 Plant Reproduction

Ch 10.1 – Intro to Plant Reproduction A. Plants can reproduce both sexually and asexually 1. In asexual reproduction a new plant can be grown from a leaf, stem or root

Grass Seeds (Sexual Repro.) Must grow about 2ft to produce seeds on top

b) Some plant species have male and female organs on separate plants 2. In sexual reproduction a sperm cell fertilizes an egg cell to form a zygote a) Some plants have both male and female reproductive organs; these can reproduce by themselves or with sex cells from other plants of the same type b) Some plant species have male and female organs on separate plants Most fruit trees have separate sexes – male trees and female trees – for fertilization one of each must be planted close by

B. Plants have a 2 stage life cycle: 1. Gametophyte Stage – produces sex cells 2. Sporophyte Stage – produces spores

Ch 10.2 – Seedless Reproduction A. Seedless plants do not produce seeds 1. Spores of seedless plants grow into a plant that produces sex cells 2. All nonvascular and some vascular plants are seedless

B. Moss Plants have a life cycle that illustrates typical sexual reproduction in nonvascular seedless plants 1. The gametophyte stage produces sex cells which fuse and develop into a sporophyte 2. The sporophyte stage produces spores

3. When spores are released and land in an appropriate environment they can grow into a new gametophyte plant 4. Nonvascular plants can also reproduce asexually if a piece of the gametophyte breaks off and lands in an appropriate environment

Moss Life Cycle

C. Most vascular seedless plants are Ferns 1. Sporophyte plants have leaves called fronds 2. Grow from underground stem called rhizome Fern emerging - fiddlehead

3. Spores are produced in spots on underside of fronds called sori 4. A spore that lands in a favorable location grows into the gametophyte stage which is called a prothallus

5. The prothallus produces sex cells 6. When fertilization occurs, the zygote develops into the sporophyte stage

Fern Life Cycle

7. Ferns may reproduce asexually when rhizomes form new brances and are separated from the main plant

Ch 10.3 – Seed Reproduction A. Pollen and seeds help many plants reproduce 1. Pollen grain – has a covering and contains gametophyte parts that produce sperm cells

2. Pollination – occurs when pollen grains are transferred to the female part of the plant which allows fertilization to take place

3. Following fertilization, the female part of the plant produces a seed which contains an embryo, stored food and a protective coat

4. Plants can develop more quickly from a seed than from a spore because a seed contains an embryo and stored food

B. Gymnosperms – develop seeds in cones 1 B. Gymnosperms – develop seeds in cones 1. A pine tree or shrub is a sporophyte plant that produces male and female cones Loblolly pine, Pinyon pine, Mugo pine

2. Female cones have two ovules which produce egg cells

Variation of Cones Red pine (middle top) California redwood (middle bottom) trees can grow tall as 35 story bldg

California Redwoods Tallest on record over 3000 ft

3. Male cones produce and release pollen

5. Seed release by a female cone can take 2 or 3 years

C. Angiosperms – produce flowers which are used in sexual reproduction and develop seeds inside of fruit

1. Flower parts: a) Stamen – male reproductive organ; made of a thin stalk called the filament and top portion with pollen called anther

b) Pistil – female reproductive organ; contains stigma with sticky nectar at top, thin stalk called style in middle and ovary at base which contains 2 ovules each with an egg cell inside

Flower Anatomy

2. The appearance of a plant’s flowers can give clues about how the plant is pollinated Birds and bees attracted to bright colors Bats can see the white of cactus flowers easily in the dark (bats are not blind! Echolocation helps in dark) Wheat has colorless flowers b/c they are pollinated by wind – no attraction of animals needed

3. After pollination and fertilization a zygote forms and grows into the plant embryo 4. The ovule develops into the seed coat and store endosperm (food) for the embryo in cotyledons 5. Flower petals fall off and a fruit develops around the seed to aid in dispersal

D. Seeds are dispersed by wind, gravity, animals and water 1 D. Seeds are dispersed by wind, gravity, animals and water 1. Germination – occurs when seed coat swells and breaks open allowing the embryo to sprout and begin growing into a new plant