Unit 1: Plant Origins & Classification Chapters 1 & 2

Unit 1: Plant Origins & Classification

Chapters 1 & 2


Unit 1 Objectives Understand the importance of

taxonomic systems and their uses Basic knowledge of divisions of plants Appreciation for how today’s crops

were developed, and the importance of continued research

Unit 1: Plant Origins & Classification Introduction

Traditionally: two basic kingdoms Animalia Plantae

Classified due to several factors: Stationary Manufacture their own food Continuous growth highly affected by the

environment

However, many do not fit well into either category, so other kingdoms have been established


Monera Bacteria and blue-green algae Protista

All other algae and protozoans Mycota

Fungi Plantae

Mosses, ferns, seed plants Animalia

Unit 1: Plant Origins & Classification Evolution of Plants

Scientists date life back 3.5b yrs. Bacteria Blue-green algae

Algae is responsible for supplying oxygen to the atmosphere to support other life forms

Land plants begin to appear ~400m yrs. ago

Unit 1: Plant Origins & Classification Geographical Distribution of Plants

Plants are not found only in the most extreme climatic conditions

What are they? Distribution can vary depending on

the plant Some extremely adaptable Some very specific What can they be adaptable/specific to?

Why are they this way?


Climate is the major determining factor Most varied plant population occurs at/near

the equator Moisture and temperature are almost never

limiting How do plants adapt?

Dry climates Develop Xeromorphic Characteristics (dry form) Small, thick leaves Spines


Dense hairiness Water-storage organs

Colder climates Growth close to the ground Protected growing points at/just beneath the

ground Climatic Zone

Plants in a similar area form a characteristic vegetation type

Biome Large area encompassing characteristic

vegetation and animal life


Major biomes include: Tropical forest Desert Tundra

Roles of Plants Basis of the food chain and energy flow Ability to convert inorganic compounds

into organic compounds in living tissues Extra energy not used for critical plant life

processes is converted to new tissue (biomass)


Edible Plants Concentrated portions of a plant

Seeds, fruits, tubers, foliage Most important food plants are of the

grass family Wheat, rice, corn, sorghum, barley

Plant foods consist of 88% of world’s calories, and 80% of proteins

Inverse relationship between high plant based diet and development of a country


Plants also a major source of world’s beverages

Can you name them, and what they are used in?

Industrial Uses Plants play a major role in virtually all

products that we have today Ex. How many products can we name

that originate from trees?


Medicinal Uses Compounds from plants can be converted

to very useful medicines In nature, and at the wrong

concentration, they may be poisonous Oils

Food reserves stored by the plant in seeds or fruits

Name some of the most common oil plants!


Taxonomy Ways to classify plants

Phylogenetic – how they look Environmental – where they grow Agricultural – what use they are grown for Natural/Morphological – how their

structure compares


Terminology Taxonomy

System used to organize plants into a classification

Nomenclature System used to assign names to plants

Artificial Classification Systems Climatic or agricultural classification

systems Depends on:

The climate the plant grows in Its uses How the environment impacts it


Botanical Systems The first method used for plant

classification Classification by morphology (size, form,

texture) Not used much today, but its influence is

still very apparent Taxonomic Classifications

Divisions within a taxonomic system are called taxa (ex. kingdom)


Most agricultural plants are considered to be members of subkingdom Embryota (land plants)

Divisions Thallophyta – algae and fungi, no tissue

differentiation Bryophyta – green plants w/out roots (mosses) Pterodophyta – green plants w/ vascular

tissue, roots, leaves, stems, no flowers Spermophyta – plants w/ true flowers and

seeds


Spermatophyta Produce true seeds

Contain an embryo that will germinate under specific conditions

True leaves, stems, roots, and vascular tissue Make up the greater majority of vegetation Two classes:

Gymnospermae Naked-seeded Woody, perennial, mostly evergreen


Reproductive structures are cones Leaves may be fernlike, scale like, strap-

shaped, needle-shaped Angiospermae

Flowers and seeds that are always protected by fruit

Further divided by the number of seed leaves found in the seed (cotyledons)

Monocotyledoneae – one cotyledon in the seed, parallel veined leaves, flower parts in 3’s or 6’s, no pith or bark on the stem but can be treelike

Ex. Grasses, cattails, lilies, bananas, bamboo


Dicotyledoneae – two cotyledons in the seed, net-veined leaves, flower parts in 4’s or 5’s or those multiples, various flower types/forms

Ex. Willows, roses, magnolia, honeysuckle Lower Subdivisions

Order, Family, Genus, Species, Form, Variety/Cultivar/Clone

Plant ID and Nomenclature Most all names are derived from Latin or Greek Can give hints to characteristics of the plant


Binomial Nomenclature Plant has 2 parts to its name (Genus &

Species) Naming is based on flowers and/or

reproductive structure Very effective because these parts are not

influenced by the environment Knowledge of flowers and its parts essential to

good plant ID Other Subgroups

Can have a third cultivar name or botanical variety Botanical variety is a plant that is similar, but

different from the wild version


Cultivar refers to cultivated variety The future of taxonomy

Will include: Chemical analysis Specific protein analysis DNA analysis – genetic finger print

More use of highly powered microscopes to very closely examine plant processes, hormones, etc.


Origin & Development of Cultivated Plants Two main regions:

Asia in the Old World Central Mexico to Chile in the New World

Neither area new what the other had until transatlantic exploration began


Unit 1: Plant Origins & Classification New Crops & New Uses

Has been a major focus in America since Colonial times

Using surpluses and decreasing demand on foreign products both in agricultural and industrial sectors

Early American Adaptations Americans have always been responsive

to market needs Corn, potatoes, squash, and tobacco has

been grown in the U.S. for many centuries


Some where exported back to Europe Corn and Potatoes where adopted quickly

because of their relative ease of production and high use

Tomatoes were suspected to be poisonous and took many centuries to adopt

Americans had to turn to other crops in order to control surpluses in order to compete w/ Europe

Tobacco, rice, cotton, timber


Beginnings of Agricultural Research USDA founded in 1862

First focus was to collect seeds for distribution to farmers and for research

Hatch Act 1887 Set up experiment stations at land-grant

colleges Initial research focused on increasing

productivity w/ better practices and varieties Created surplus problems Research had to turn to additional uses for

commodities


WWI had a great impact on the development of new plants and uses in the U.S. due to supply cutoff

Specifically medicinal plants Overproduction of cotton threatened the market in

the southern U.S. Through research and development, Carver

convinced many growers to plant peanuts and sweat potatoes

Founded peanut oil Peanut acreage grew 4x from 1910 to 1940 Carver also founded new uses for cotton and

soybeans


Agricultural Adjustment Act 1938 Response to severe surpluses and lack of

export market Established 4 national research stations

geographically based on crops grown in that area

WW II Stimulated research due to needs for the war Many new products/uses developed

Synthetic rubber, dehydrated foods, etc. Mass production of penicillin


Postwar Research Attention again focused on dealing w/

surpluses due to soaring production as a result of advancements in chemicals/machinery

Development of many other products Frozen orange juice – stimulated

production of O.J. concentrate from 226,000 g in 1945 to 84,000,000 g in 1960

Other frozen foods Instant potato flakes Wrinkle-resistant cotton


New Sources of Demand Response to rising surpluses, increased

productivity, and dependence on foreign materials

High oil prices of 1970’s stimulated research in ethanol and soy ink

Much focus has been centered on biodegradability and conservation of natural resources


Most research has focused on increased uses for current products

Less research on the introduction of new plants due to difficulty in getting them to grow in the climate and resistance of farmers to grow new crops

Guayule – for rubber production Kenaf – substitutes for wood pulp in paper

production Crambe – industrial oil


The Future We have the research base and facilities to

greatly expand our research if/when needed

Demand for research will continue to be great to meet needs for new crops and decrease demand on foreign imports

New uses and products would increase the need for manufacturing and process plants which would stimulate the economy


Protection of Germ Plasm <.1% of plant species are used in

agriculture Scientists are concerned about preserving

this resource Genes can be used in the future to create

new plants, new product uses, or have crops that will adapt to adverse environments

More genes will be added to the pool for future uses


Unit 1 Assignment:

Documents

Unit 1: Plant Origins & Classification Chapters 1 & 2