Plants: An IntroductionPlants: An Introduction

The The Plant KingdomPlant Kingdom can be viewed as having can be viewed as having

the true terrestrial plants and those that are the true terrestrial plants and those that are

““almostalmost”” true terrestrial plants.true terrestrial plants.

Outline Outline

� Key concepts

� Important roles of Plants

provide food, air (oxygen), clothing, etc.

� Comparison

� Classification:

� Evolutions

� Conclusions

Key Concepts:Key Concepts:

� The plant kingdom consists of multicelled

photoautotrophs

�Nearly all plants live on land

� Plants have structural adaptations that allow

them to photosynthesize, absorb water and

ions, and conserve water

� Land plants are reproductively adapted to

withstand dry periods

Key Concepts:Key Concepts:

� Early divergences gave rise to the bryophytes,

then the seedless vascular plants, and then the

seed-bearing vascular plants

�Gymnosperms are the seed-bearing vascular

plants and the angiosperms are also vascular

plants that bear flowers and seeds

�Angiosperms include two classes of flowering

plants

� Eudicots and Monocots

ComparisonComparison

Animals Plants

1. heterotrophic autotrophic

2. stop growing continuing growing

3. reproductive tissue reproductive tissue

present all times not present at all times

Classification Classification & Evolution& Evolution

1. Bryophytes: Non-vascular Plants

2. Seedless Vascular Plants

3. Gymnosperms: Seed-bearing Plants

4. Angiosperms: The Flowering Seed-

Bearing Plants

BryophytesBryophytes

�Mosses

�Nonvascular

�Moist habitats

mostly

� Small

�< 20 cm tall

� Simplest plants

Moss-covered rocks

Seedless Vascular PlantsSeedless Vascular Plants

�Whisk ferns,

Lycophytes,

Horsetails, Ferns

�Has vascular tissues

�Habitat

�Moist places

�Sperm needs

water to reach egg

LycopodiumPsilotum

Equisetum

FernsFerns

GymnospermsGymnosperms--Plants with Plants with ““NakedNaked”” SeedsSeeds

� Conifers, Cycads, Ginkgos, Gnetophytes

�Conifers - cones

�Pines, cypress, firs, spruces, redwoods

Gymnosperm DiversityGymnosperm DiversityBristlecone pine

A cycad’s

seed-bearing cone

Gymnosperm DiversityGymnosperm Diversity

Ginkgo Ginkgo

seeds

Ginkgo

leaf and

fossil

Gymnosperm DiversityGymnosperm Diversity

Welwitschia mirabilis– GnetophyteIt grows in hot deserts of Africa with a deep taproot. It has

one or two strap-shaped leaves that split lengthwise

repeatedly as the plant ages.

Pine treesPine trees

Angiosperms: flowering Angiosperms: flowering seed plantsseed plants

� The dominant plant form on earth (>250,000

species)

� Flowers to increase insect pollination

� Fruit to protect the seed and developing embryo until favorable germination conditions occur

� Broad leaves to increase photosynthesis during the growing season are shed during periods of cold and drought

AngiospermsAngiospermsThe Flowering SeedThe Flowering Seed--Bearing PlantsBearing Plants

� Flowers

� Coevolution with

pollinators

� Insects Bats

Birds

� Seed

�Ovary

EudicotsEudicots and Monocotsand Monocots

�Almost 180,000 Eudicots

�Cabbage and Daisies

�Flowering shrubs and trees

�Water lilies

�Cacti

�About 80,000 Monocots

�Orchids, palms, grasses,

crop plants, rice

AngiospermsAngiosperms

Evolution of PlantsEvolution of Plants

In ConclusionIn Conclusion

�Green algae probably gave rise to plants

� Trends in evolution can be identified by comparing

different lineages

�Mosses are bryophytes, nonvascular plants

� Vascular plants are adapted to land

� The seedless vascular plants include the whisk

ferns, lycophytes, horsetails, and ferns

In ConclusionIn Conclusion

�Gymnosperms and angiosperms are vascular

plants

�Only angiosperms produce flowers