weed biology and identification-205 target students: m.sc. students in weed science lecture: dr....
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Weed Biology and Identification-205
Target students: M.Sc. Students in Weed Science
Lecture:
Dr. Majid AghaAlikhani (Ph.D.)
Academic position :
Associate Prof. of Tarbiat Modares [email protected]
1
Plant Taxonomy
By: Johnny M. JessupAgriculture Teacher/FFA
Advisor
Introduction
• Taxonomy is the science of classifying and identifying plants.
• Scientific names are necessary because the same common name is used for different plants in different areas of the world.
• Latin is the language used for scientific classification.
Taxonomy: D.I.N.C.
Description
Identification
Nomenclature
Classification
DescriptionAssignment/listing of features or attributes to a taxon
character= a featuree.g., “flower color”
character states= two or more forms of a charactere.g., “white,” “red,” “yellow”
Identification
Associating an unknown taxon with a known one
How?taxonomic keycompare to a
photograph/illustrationcompare to a specimenask an expert
NomenclatureFormal means of naming life.
E.g., binomial nomenclature for species names:
For Adenostoma fasciculatum Hook. & Arn.
Adenostoma = genus namefasciculatum = specific epithetAdenostoma fasciculatum =
species nameHooker & Arnott = authors of
species name
Classification
= placing objects, e.g., life, into some type of order.
Taxon = a taxonomic group (plural = taxa).
Why classify??
How to classify life
Phenetic classification
Based on overall similarity
Those organisms most similar to one another are classified more “closely” together.
Problem with phenetic class.:
Can be arbitrary, e.g., classify these:
Definitions
Taxonomy -- the naming of groups (taxa, singular taxon)
Systematics -- a method (or system) for classifying organisms into groups
Why classify??
Goals of Classification
• Simplify
• Communicate
• Predict
How to classify plants?
Functional classifications Based on function or overall similarity No assumption of evolutionary relationship
History - Functional classification systems All cultures classify plants in ways meaningful to them
Examples of early plant classifications
2000 BC - Indian (Ayurvedic) texts described medicinal plants
1000-1700 AD - “Age of Herbals” in Europe
Botanical tradition
Carolus Linneaus (Systemae naturae, 1732)
- defined groups based on sexual characters
- developed binomial system of plant nomenclature
Engler, Bessey, Cronquist etc. (1800 - 1980s)
- sought to define evolutionary groups of plants
- published many regional floras (still in use)
History - Evolutionary classification systems
Evolutionary classification(includes both traditional systematics and modern phylogenetics)
1. Living species are related to one another by descent from common ancestors
2. Shared character states are clues to relatedness
Reasoning
What about convergent evolution??
Modern solution: Phylogenetic systematics Reconstructs relationships using lots of characters Now, primarily uses DNA sequence data
From Nickrent et al.
Land plants (Embryophytes)
Vascular plants
~450 millionyears ago
Present
Bryophytes(mosses, liverworts)
Lycopods(club mosses)
Seed plantsMonophilites
(ferns, horsetails)
woodiness
seeds
tracheids(vascular cells for water transport)
“true” leaves
multiple adaptations to life on land
Karl von Linne (1707-1778)
• Swedish botanist• Developed binomial
classification scheme for plants.
• Uses two Latin words to indicate the genus and the species.
• Changed his name to the Latin name of Carolus Linnaeus.
Scientific Names
• The first word is the genus and the second word is the species.
• If there are additional words, they indicate the variety or cultivar.
Genus
• Plants in the same genus have similar characteristics.
• Examples:• Quercus – Oaks• Acer – Maples• Pinus – Pines• Ilex – Hollies• Cornus – Dogwoods• Ficus – Figs
Species
• Plants in the same species consistently produce plants of the same types.
Species
• A distinct types of organism capable of breeding with other members of its own kind - but not with other species….
• Basic category in biological nomenclature
Varieties (subspecies)
• Sargent
• Quercus alba L. var. alba• Quercus alba L. var. latiloba Sarg.
• If Q. latiloba was a new species?• Quercus latiloba Sarg.
hybridization
• Q. velutina X Q. rubra X Q. palustris
• Echinacea pallida
• Echinacea paradoxa
• Echinacea pallida X paradoxa
Relationship between Genus and Species
• Genus - a group of related species
• Quercus (oaks) Carya (hickories)• rubra - ovata• velutina - cordiformes• alba
Related• 1. Have similar characteristics
(may hybridize)• 2. Have a common ancestor back
in evolutionary time• velutina rubra alba
Related• 1. Have similar characteristics
(may hybridize)• 2. Have a common ancestor back
in evolutionary time• ovata cordiformes
Scientific Classification
• The broadest category of scientific classification is the Kingdom.• Either Plant or Animal
• The broadest category of the plant kingdom is Division or Phylum.
Scientific Classification
Natural System
• Our present system attempts to group organisms in accordance with natural (evolutionary) relationships.
• Homology• internal structures, embryology, DNA,
proteins• Analogy
• based on superficial characteristics• outward form and function
Kingdoms
Plants Aristotle Gr 4thC BC
Animals Aristotle Gr
Protista E. Haeckel Ger 19thC
Fungi R H Whitaker USA 20thC
Archebacteria (Archaea) C. Woese USA 20th C
Eubacteria (Bacteria) C. Woese USA 20th C
Domains
Rank Classification
Hierarchical - each higher rank is inclusive of lower ranks Rank Example EndingPhylum Magnoliophyta -phyta
Class Liliopsida -opsidaOrder Liliales -ales
Family Liliaceae -aceaeGenus Lilium
Species Lilium parryi
Divisions
• The four most important divisions of the plant kingdom are….• Thallophites• Bryophytes• Pteriophytes• Spermatophytes
Spermatophytes
• Includes flowering or seed-bearing plants.
• The two subdivisions are….• Gymnosperms• Angiosperms
Kingdom Viridiplantae (green plants)Phylum/Division
Embryophyta (land plants)Subphylum
Tracheophytina (vascular plants)Class
Angiospermopsida (angiosperms)Subclass
CaryophyllidaeOrder
Caryophyllales Family
Portulacaceae (Purslane family) Genus
LewisiaSpecies
Lewisia rediviva
Lewisia rediviva (Bitterroot)
Plant nomenclature in practice
Plant nomenclature in practiceHigher ranks
- Each rank has a characteristic ending (ex. -idae for subclasses, -ales for orders)
- Ideally, all taxa are monophyletic, but ranks are arbitrary
- In this class, we’ll focus on lower taxonomic levels
--> subclass (ex. Rosidae vs. Asteridae)
--> family (ex. Salicaceae vs. Betulaceae)
--> genus (ex. Populus vs. Salix)
--> species (ex. P. tremuloides vs. P. deltoides)
Plant nomenclature in practice
ICBN (International Code of Botanical Nomenclature)
Goal: Standardization of scientific names for plants
- First adopted in 1903; includes fungi, lichens and algae
Basic rules
- Every taxon must have a type specimen
- Names of higher ranks must be based on names of lower ones
- Priority of publication determines “correct” name
- Only 1 name is allowed per taxon, 1 taxon per name
Standard Endings (ICBN)
• Division: phyta• Class: opsida• Order: ales• family: aceae• Genus:• species:
Plant nomenclature in practice
Families- All end in -aceae (easiest to pronounce a-cee-ee)
- Older alternate names also allowed for 8 familiesexamples: Crucifereae = Brassicaceae (mustard family) Umbellifereae = Apiaceae (carrot family) Compositae = Asteraceae (sunflower family)
- Always capitalize family names
Plant nomenclature in practice
Species names (“scientific names”) are Latin binomials
Lewisia rediviva Pursh.
• Genus (pl. genera)• Always capitalized• Abbreviated on 2nd use
(L. rediviva)
• Authority• Specific epithet• Not capitalized• Often a descriptive adjective
Always underline or italicize species names (genus + specific epithet)
Plant nomenclature in practice
Why do names change?• New evolutionary data
• Rediscovery of older names• Lumpers vs. splitters
Agropyron spicatumElymus spicatusPsuedoroegneria spicataBluebunch wheatgrass
Plant Characteristics
Identifying Plants
• Physical characteristics are used to identify plants which include….• Life Cycle• Form• Foliage Retention• Plant Parts• Use & Location
Life Cycle
• Annuals• Plants that complete their life cycle in
one year.• Biennials
• Plants that complete their life cycle in two years.
• Perennials• Plants that live more than two years.
Growth Habits
• Trees• Shrubs• Vines
Growth Forms
• Columnar• Spreading• Weeping
• Round• Oval• Pyramidal
Growth Forms
Spreading
Columnar
Weeping
Growth Forms
Round Oval Pyramidal
Foliage Retention
• Deciduous• Loses leaves during the dormant
season.• Evergreen
• Keeps leaves and remains green year-round.
Plant Parts – Leaf
• Arrangement• Shapes• Color• Vein Pattern• Form – Simple or Compound• Margin• Surface
Leaf Arrangement – Simple
Leaf Arrangement – Compound
Leaf Shape
Vein Pattern
• Pinnate• Palmate• Parallel• Dichotomous
Leaf Margin
Leaf Surface
• Glabrous• Pubescent• Villous• Tomentose
• Scabrous• Glaucous• Rugose• Glandular
• There are 8 common leaf surfaces.
Leaf Surface – Glabrous
• The surface is smooth, not hairy.
Leaf Surface – Pubescent
• Short, soft hairs cover the surface.
Leaf Surface – Villous
• Long, straight hairs cover the surface.
Leaf Surface – Tomentose
• Covered with wool-like hair.
Leaf Surface – Scabrous
• Covered with short, prickly hairs.
Leaf Surface – Glaucous
• Covered with a bluish-white waxy substance.
Leaf Surface – Rugose
• Surface is wrinkly.
Leaf Surface – Glandular
• Glands filled with oil or resin cover the surface.
Plant Parts – Flowers
• Color• Shape• Size
Plant Parts – Bud & Stem
• Shape & Color• Stem Modifications
• Thorns• Spines• Prickles
Plant Parts – Modified Stems
Thorn
Prickle Spine
Plant Parts – Roots
• Tap• Fibrous• Bulb
Plant Parts – Roots
Tap Root
Tuberous Root
Fibrous Root
Plant Parts – Fruit
• Cones• Nuts (Acorns)• Pomes (Apple)• Drupes (Peach)
• Brambles (Raspberries)• Capsules (Willow)• Samara (Maple)
Plant Parts – Fruit
Cones
Acorns
Pomes
Plant Parts – Fruit
Drupes
Brambles
Capsules
Samara
Use & Location
• Not absolute, but helpful.• Indoor or outdoor.• Altitude• Wet or dry• Hardiness Zone• Sun, partial shade, or shade.• Landscape purpose – specimen, border,
etc.
Collecting, Preparing and Preserving Plants
Collecting, Preparing and Preserving Plants
Collecting, Preparing and Preserving Plants
Designed By:
• Johnny M. Jessup, FFA Advisor• Hobbton High School