Reproduction in Flowering Plants
1.
2.
Reproduction is the goal of every living thing? a.
Evolution states that every organism’s goal is to survive long enough to reproduce and pass on your genes b.
Though humans can only reproduce sexually many plants are capable of both sexual and asexual reproduction i.
Sexual reproduction –
1.
Advantages a.
More genetic diversity b.
Some offspring will be more fit than their parents. c.
Populations can adapt and evolve to a changing environment
2.
Disadvantages a.
b.
Isolated plants cannot reproduce.
Some offspring will be less fit than their parents. c.
Reproduction occurs at a slower rate ii.
Asexual reproduction -
1.
Advantages a.
Allows plant to reproduce more quickly. b.
c.
A single isolated plant can reproduce.
If parent plant is fit for its environment, each offspring will be equally as fit.
2.
Disadvantages a.
Does not allow the population to evolve. b.
No genetic diversity in offspring, so populations can be wiped out by a single environmental change.
Reproduction in flowering plants a.
Flowers - reproductive organs that are composed of four different kinds of specialized structures: i.
sepals
1.
Location: The outermost floral part ii.
2.
Structure: The thickest, waxiest and toughest part of the flower.
3.
Petals
Function: To protect the flower iii.
1.
Location: Just inside the sepals
2.
Structure: Thin, delicate, and have pigments other than chlorophyll
3.
Function: To attract the correct pollinator stamens (Male structure of the flower)
1.
Location: Just inside and above the petals
2.
Structure: made of 2 parts i.
Filament: a thin stalk ii.
Anther: a saclike structure in which pollen grains are formed

3.
Function: To produce and transfer pollen grains iv.
carpals (female structure of a flower)
1.
Location: the center-most flower structure
2.
Structure: made of 3 parts a.
Stigma - the top of the carpel, it is sticky to capture pollen. b.
Style – a long stalk-like tube connecting the stigma to the ovary. Provides a pathway for the sperm to get to the egg
3.
Pollination and fertilization c.
Ovary – contains the eggs and seeds a.
Pollen Grain - the male gametophyte of seed plants i.
Each pollen grain contains 2 sperm cells b.
ii.
Pollen grains are designed to stick to animals or to be carried by wind.
Pollination - the transfer of pollen grains from anther to stigma c.
Pollination leads to sexual reproduction (whether it is self-pollination or crosspollination) i.
Cross-pollination - when pollen grains are transferred to a flower on another individual of the same species. ii.
1.
Cross-pollination leads to greater genetic variation
Self-pollination - pollination that occurs within the same flower or different flowers of the same plant.
4.
iii.
1.
Self-pollination leads to inbreeding: mating of genetically similar individuals
2.
Inbreeding can increase the concentration of harmful genes in offspring
Some plants have mechanisms for preventing self pollination
1.
flowers have only stamen and other flowers have only a carpel
2.
release pollens before or after the stigma of that flower is receptive to pollen.
3.
genes that prevent self-pollination d.
Fertilization: The process where the sperm cell and the egg cell join to form an embryo (occurs after pollination)
After the pollen grain lands on the stigma it grows a pollen tube, two sperms from the pollen grain travel through the pollen tube to get to the ovule.
5.
Co-evolution of Flower Plants and Animal Pollinators a.
Co-evolution - when two species are so closely related to each other when species changes, the second species will change in response. b.
Flowering plants and animals have coevolved i.
Flowers attract animals in a variety of ways:
1.
Showy petals a.
Insects have a good sense of smell and can see UV light.
Cannot see red b.
Birds can see red, orange and yellow very well. Do not a strong sense of smell.

c.
Bats cannot see well, but have a good smell (Flowers are white, scented and bloom at night)
2.
Food a.
Nectar: a sugary solution
3.
b.
Pollen: a protein rich food c.
Generation of Fruit
Smell
6.
Wind Pollinated Flowers a.
Flower are not big, bright, colorful, scented, or filled with nectar b.
Wind-pollinated plants produce huge quantities of pollen to insure that at least some of it lands on a female plant
7.
Seed Dispersal a.
After fertilization . . . i.
The ovule develops a seed ii.
The ovary develops into a fruit iii.
Fruit - the ripened ovary of a plant that help protects and disperse seeds. b.
Seeds from a plant can be dispersed in a number of ways i.
Dispersal by Animal
1.
2.
Plant produce fruits to provide food for animals not the seeds
Animals eat the fruit along with the seeds
3.
The seed coat protects the seed from being digested.
4.
Seed sprouts in animal feces far away from parent plant.
8.
ii.
Seed Dormancy
1.
Dormancy – the period of time when the seed is alive but not growing. a.
Advantages of Seed Dormancy: i.
Allows time for long-distance seed dispersal. ii.
Allows seeds to germinate under ideal conditions
1.
(Seeds are dormant for the winter and germinate in the spring) b.
What factors end seed dormancy? i.
Temperature and Moisture
Seed Germination a.
Germination - the process where seeds and spores sprout and begin to grow i.
All seeds need water to germinate ii.
The water causes the inside of the seed to swell and eventually crack the seed coat iii.
The root of the embryo emerges through the crack first and the shoot emerges second.
9.
Asexual Reproduction (reproduction without seeds) a.
Not all plants need seeds to reproduce i.
Cuttings - plant stems often take root if they are cut off and pushed into soil

ii.
Grafting – a piece of the stem is cut from one parent plant and attaches to another.
1.
Used to reproduce seedless plants and plants that cannot be made using cuttings.
2.
Only works when plants are closely related. a.
Ex: A branch of a lemon tree is attached to an orange tree