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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.

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Presentation on theme: "Weed Biology and Identification-205 Target students: M.Sc. Students in Weed Science Lecture: Dr. Majid AghaAlikhani (Ph.D.) Academic position : Associate."— Presentation transcript:

1 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 University 1

2 Plant Taxonomy By: Johnny M. Jessup Agriculture Teacher/FFA Advisor

3 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.

4 Taxonomy: D.I.N.C. Description Identification Nomenclature Classification

5 Description Assignment/listing of features or attributes to a taxon character = a feature e.g., “flower color” character states = two or more forms of a character e.g., “white,” “red,” “yellow”

6 Identification Associating an unknown taxon with a known one How? taxonomic key compare to a photograph/illustration compare to a specimen ask an expert

7 Nomenclature Formal means of naming life. E.g., binomial nomenclature for species names: For Adenostoma fasciculatum Hook. & Arn. Adenostoma = genus name fasciculatum = specific epithet Adenostoma fasciculatum = species name Hooker & Arnott = authors of species name

8 Classification = placing objects, e.g., life, into some type of order. Taxon = a taxonomic group (plural = taxa).

9 Why classify??

10 How to classify life Phenetic classification Based on overall similarity Those organisms most similar to one another are classified more “closely” together.

11 Problem with phenetic class.: Can be arbitrary, e.g., classify these:

12 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

13 How to classify plants?  

14 Functional classifications  Based on function or overall similarity  No assumption of evolutionary relationship

15 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

16 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

17 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

18 What about convergent evolution??

19 Modern solution: Phylogenetic systematics  Reconstructs relationships using lots of characters  Now, primarily uses DNA sequence data From Nickrent et al.

20 Land plants (Embryophytes) Vascular plants ~450 million years ago Present Bryophytes (mosses, liverworts) Lycopods (club mosses) Seed plants Monophilites (ferns, horsetails) woodiness seeds tracheids (vascular cells for water transport) “true” leaves multiple adaptations to life on land

21 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.

22 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.

23 Genus Plants in the same genus have similar characteristics. Examples: Quercus – Oaks Acer – Maples Pinus – Pines Ilex – Hollies Cornus – Dogwoods Ficus – Figs

24 Species Plants in the same species consistently produce plants of the same types.

25 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

26 Varieties (subspecies) Sargent Quercus alba L. var. alba Quercus alba L. var. latiloba Sarg. If Q. latiloba was a new species? Quercus latiloba Sarg.

27 hybridization Q. velutina X Q. rubra X Q. palustris Echinacea pallida Echinacea paradoxa Echinacea pallida X paradoxa

28 Relationship between Genus and Species Genus - a group of related species Quercus (oaks)Carya (hickories) rubra- ovata velutina- cordiformes alba

29 Related 1. Have similar characteristics (may hybridize) 2. Have a common ancestor back in evolutionary time velutina rubra alba

30 Related 1. Have similar characteristics (may hybridize) 2. Have a common ancestor back in evolutionary time ovata cordiformes

31 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.

32 Scientific Classification Kingdom Phylum/Division Class Order Suborder Family Genus Species


34 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

35 Kingdoms

36 Domains

37 Rank Classification Hierarchical - each higher rank is inclusive of lower ranks RankExampleEnding PhylumMagnoliophyta-phyta ClassLiliopsida-opsida OrderLiliales-ales FamilyLiliaceae-aceae GenusLilium SpeciesLilium parryi

38 Divisions The four most important divisions of the plant kingdom are…. Thallophites Bryophytes Pteriophytes Spermatophytes

39 Includes flowering or seed-bearing plants. The two subdivisions are…. Gymnosperms Angiosperms

40 Kingdom Viridiplantae (green plants) Phylum/Division Embryophyta (land plants) Subphylum Tracheophytina (vascular plants) Class Angiospermopsida (angiosperms) Subclass Caryophyllidae Order Caryophyllales Family Portulacaceae (Purslane family) Genus Lewisia Species Lewisia rediviva Lewisia rediviva (Bitterroot) Plant nomenclature in practice

41 Higher 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)

42 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

43 Standard Endings (ICBN) Division: phyta Class: opsida Order: ales family: aceae Genus: species:

44 Plant nomenclature in practice Families - All end in -aceae (easiest to pronounce a-cee-ee) - Older alternate names also allowed for 8 families examples: Crucifereae = Brassicaceae (mustard family) Umbellifereae = Apiaceae (carrot family) Compositae = Asteraceae (sunflower family) - Always capitalize family names

45 Plant nomenclature in practice Species names (“scientific names”) are Latin binomials Lewisia rediviva Pursh. Genus (pl. genera) Always capitalized Abbreviated on 2 nd use (L. rediviva) Authority Specific epithet Not capitalized Often a descriptive adjective  Always underline or italicize species names (genus + specific epithet)

46 Plant nomenclature in practice Why do names change? New evolutionary data Rediscovery of older names Lumpers vs. splitters Agropyron spicatum Elymus spicatus Psuedoroegneria spicata Bluebunch wheatgrass

47 Plant Characteristics

48 Identifying Plants Physical characteristics are used to identify plants which include…. Life Cycle Form Foliage Retention Plant Parts Use & Location

49 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.

50 Growth Habits Trees Shrubs Vines

51 Growth Forms Columnar Spreading Weeping Round Oval Pyramidal

52 Growth Forms Spreading Columnar Weeping

53 Growth Forms Round Oval Pyramidal

54 Foliage Retention Deciduous Loses leaves during the dormant season. Evergreen Keeps leaves and remains green year- round.

55 Plant Parts – Leaf Arrangement Shapes Color Vein Pattern Form – Simple or Compound Margin Surface

56 Leaf Arrangement – Simple

57 Leaf Arrangement – Compound

58 Leaf Shape

59 Vein Pattern Pinnate Palmate Parallel Dichotomous

60 Leaf Margin

61 Leaf Surface Glabrous Pubescent Villous Tomentose Scabrous Glaucous Rugose Glandular There are 8 common leaf surfaces.

62 Leaf Surface – Glabrous The surface is smooth, not hairy.

63 Leaf Surface – Pubescent Short, soft hairs cover the surface.

64 Leaf Surface – Villous Long, straight hairs cover the surface.

65 Leaf Surface – Tomentose Covered with wool-like hair.

66 Leaf Surface – Scabrous Covered with short, prickly hairs.

67 Leaf Surface – Glaucous Covered with a bluish-white waxy substance.

68 Leaf Surface – Rugose Surface is wrinkly.

69 Leaf Surface – Glandular Glands filled with oil or resin cover the surface.

70 Plant Parts – Flowers Color Shape Size

71 Plant Parts – Bud & Stem Shape & Color Stem Modifications Thorns Spines Prickles

72 Plant Parts – Modified Stems Thorn Prickle Spine

73 Plant Parts – Roots Tap Fibrous Bulb

74 Plant Parts – Roots Tap Root Tuberous Root Fibrous Root

75 Plant Parts – Fruit Cones Nuts (Acorns) Pomes (Apple) Drupes (Peach) Brambles (Raspberries) Capsules (Willow) Samara (Maple)

76 Plant Parts – Fruit Cones Acorns Pomes

77 Plant Parts – Fruit Drupes Brambles Capsules Samara

78 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.

79 Collecting, Preparing and Preserving Plants



82 Designed By: Johnny M. Jessup, FFA Advisor Hobbton High School

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