The Plant Kingdom: An Overview

• Plants play an integral role in all aspects of life, shaping the physical environment and influencing climate
• Human societies depend on plants for nutrition, medicinal compounds, and industrial materials
• All plants are thought to have descended from a single, common ancestor
• Transition to land required adaptations to avoid drying out, disperse reproductive cells in air, structural support, and filter sunlight

The Plant Kingdom

• Plants are set apart from other kingdoms by their ability to photosynthesize and the presence of cellulose in their cell walls
• Most plants reproduce sexually but have asexual methods of reproduction as well
• Plants exhibit indeterminate growth, continuing to grow in body mass until they die
• Mosses, ferns, conifers, and flowering plants are all members of the plant kingdom
• There are close to 300,000 identified species of plants

Early Plant Life: Green Algae and the Evolutionary Pathway to Photosynthesis

• Some biologists think all photosynthetic eukaryotes are plants, while others limit the plant kingdom to green algae
• Green algae, specifically Charophytes, are considered plants by those who track evolutionary straight monophylytic lines
• Green algae ancestors gained photosynthetic ability through endosymbiosis of a green photosynthetic bacterium 1.65 billion years ago

Plant Adaptations to Life on Land

• Challenges faced by plants adapting to terrestrial environments include desiccation, need for structural support, mutagenic radiation, and new fertilization strategies
• Successful land plants developed strategies to deal with challenges such as desiccation

Additional Land Plant Adaptations

• Adaptations include tolerance, colonizing humid environments and resistance to desiccation
• Key adaptations of land include alternation of generations, sporangium, gametangium, apical meristem tissue and evolution of a cuticle
• Cuticle also prevents intake of carbon dioxide for photosynthesis which is why stomata emerged
• Plants synthesize complex organic molecules such as alkaloids to deter animals

The Major Divisions of Land Plants

• Land plants are divided into vascular and nonvascular plants
• Bryophytes (liverworts, mosses, and hornworts) are seedless and nonvascular
• Vascular plants have cells that conduct water and solutes through the plant body

Seedless Plants

• In the late Ordovician period vascular plants appeared
• First vascular plants were similar to lycophytes
• Seed plants dominated the landscape and grew in the enormous swampy forests

Bryophytes

• Bryophytes are nonvascular plants with about 18,000 species mostly in damp habitats
• Bryophytes are commonly referred to as nonvascular plants.
• All bryophytes' organs belong to the haploid organism, or gametophyte
• Bryophytes is divided into 3 divisions: liverworts, hornworts and mosses

Liverworts, Hornworts and Mosses

• Liverworts are most closely related to ancestors from the land and diversified to over 6000 species
• Hornworts have colonized land and there are about 100 species
• Over 12,000 species of mosses have been cataloged

Seedless Vascular Plants

• Vascular plants are dominant
• Vascular plants are about 275,000 species
• Key adaptations of vascular plants: xylem and phloem, roots and leaves

Evolution and Adaptation of Vascular Plants

• First fossils that show the presence of vascular tissue were dated to the Silurian period
• Xylem is the tissue that transports of water and minerals
• Roots are important for the plant because are not well preserved in the fossil record
• Roots transfer water and minerals from the soil to the rest of the plant
• Accompanied by the sporophyte, leaves improve photosynthetic efficiency

Seedless Vascular Plants

• By the Devonian period plants had vascular tissue, defined leaves and root systems
• During the Carboniferous period, swamp forests covered most of the land
• Modern-day seedless vascular plants include club mosses, horsetails, ferns, and whisk ferns
• Lycophyta are the earliest group of seedless vascular plants of the club moss family

Horsetails, Ferns and Whisk Ferns

• Ferns and whisk ferns belong to Pterophyta groups of plants
• Horsetails have a single genus, Equisetum
• Ferns are considered the most advanced seedless vascular plants and are linked to seed plants

Importance of Seedless Vascular Plants

• Mosses and liverworts are often the first macroscopic organisms to colonize an area
• Bryophytes make soil more amenable to support other plants
• Since bryophytes have neither roots or protective cuticles, rainwater penetrates the tissues.
• By promoting the environment ferns are contributing to the environment

Evolutionary Adaptation of Seed Plants

• The life cycle of bryophytes and pterophytes is characterized by the alternation of generations
• Completion of the life cycle requires water
• Gametophytes mature within the spores meaning they are not free living
• All spermatophytes are heterosporous, creating megaspores and microspores
• Key innovations: pollen and seed which help in land fertilization and drier conditions

Gymnosperms

• Seeds and pollen are what differentiate gymnosperms
• First distinct plants appeared close to 350 million year ago
• Gymnosperms were preceded "first naked seed plants"
• Gymnosperms dominated the landscape

Conifer Structure

• Gymnosperm seeds are not enclosed in an ovary; exposed on cones
• Sporophylls are structure to produce sporangia
• Gymnosperms were the dominant phylum in the Mesozoic

Life Cycle of a Conifer

• The life cycle of conifer gymnosperm includes alternation of generations, dominant sporophyte
• Both male and female sporophylls grow on the same plant
• Pines are heterosporous and produce male and female megaspores The microsporocytes create microspores by meoisis

Diversity of Gymnosperms

• Consists of four major divisions and over 1000 known species
• Coniferophyta and Ginkophyta are similar during secondary composition
• Gnetophyta is considered the closest to angiosperms

Coniferophyta

• Conifers usually bear scale that limit transpirational water loss
• Adapted to deal with cold and dry
• Includes trees such as pines

Cycadophytes

• Cycads thrive in mild climates
• They bear large cones
• Dominated the landscape during the age of the dinos
• Attractive shape: garden ornaments

Ginkgophytes

• Single surviving species is the Ginkgo biloba
• Fan-shaped leaves turn yellow in autumn
• Buddhist monks cultivated Ginkgo

Gnetophytes

• Closest relatives to modern angiosperms/
• Includes three dissimilar genera of plants
• All genitives posses vessel elements in the xylem

Angiosperms

• Angiosperms have floral structures to target pollinating insects
• Fruit protects the developed embryo
• The structures of fruits reflect the dispersal of seeds

Flowers

• Flowers are sporophylls organized around central stalks
• Same structures: sepals, petals, pistils, and stamens
• Three sepals and three petals that look virtually identical
• Pollinated by insects and also vivid colors

Fruit

• The seed forms in an ovary
• Food commonly called vegetables are actually fruit
• Fleshy fruit include berries or apples
• Dry seed include rice wheat and nuts
• Agent of dispersal, reflecting mode of dispersal

The Life Cycle of an Angiosperm

• Angiosperms are also heterosporous
• They produce microspores that develop pollen grain
• Megaspores form an ovule that contains female gematophytes

Double Fertilization

• Sperm combines with egg, making diploid zygote for future embryo
• A long structure leads style where pollen is desposited
• Some flowers do self pollinate.
• Barriers to self-pollination help pollination

Diversity of Angiosperms

• Angiosperms are classified in a single divison, Anthophyta
• Flowering plants are devided into two major groups
• Categorized separtaley, corrisponds to Magnildiae

Basal Alperms (Magnoliidae)

• Tall fragrant flowers with large parts and considered
• Laurales are small trees and shrubs from warmer climates
• Most live in freshwater areas

Monocots/Dicots

• Most of the world's crops are flower
• They grow in tropical climate and create small flowers
• They have small flowers without petals and arranged in lone spikes that are tightly held

Eudicots

• Eudicots or true dicots, known has presence of two cotyledons
• They are a network in the leaves
• Usually anchored bu one main root devoloped from the embrionic radicle

The Role of Seed Plants

• Plants help stabalize soil, carbon cycling and moderate climate
• Plants help for medicinal use and industry
• Hypothesized that flowering plants and insects has recicved support

Animals and Plants: Herbivory

• The colvolution of herbivores and plants defenses observed in nature
• Plants cant outrun predators or mimicry
• Seeds and acorn of unripe persimmon provide high amounts of alkaloids that dont attract animals
• Help for their own benefit, despersal of fruit can have mulistic relationship

Animals and Plants: Pollination

• Grases are successful as flowering plants that transport wind
• Animals are help transport pollination
• Plants develop many adapATIONS To ATRACt polllinators

The Importance of Seed Plants in Human Life

• Seed plants are fundamental in human diets
• Developed during agricultural evolution
• Staple crops and not the only food deribves, provide nutrients

Food Production

• Distilled from corn sugarcane and other things
• Different plant parts, come from stanens and buds
• Herbs of flavour come from dired leave and fruit
• Olis from flower provide scent to perfumes
• Alcohol, feemntation of plant derived dguars
• Textile dyes are mostly plant origin
• Quantiify ornimental seed plants that have beatufil ading features

The Properties of Plants

• Medicinal properties have been important across time
• Therapeutic drugs from the time peirod derive and synthnizes from plants
• Important same platn can have remedy at low concentrate, addictive at high, or poison at death

The Tree of life

• All organims have relatives derived from their evoutionary history
• Phylomgeny : connection of plants in relatives
• All at the tops of ranches desrcibe species, what a node is called

The Tree of life Continued

• Phylogenetic tres: describe relationships from darwin time
• Traditional methods: homologous anatomy from the same
• What you discover how from relationships
• What is used for dNA analysis