Dendrology Lecture Notes 1.0

I.  Taxonomy

    A.  Identification

    B.  Nomenclature

    C.  Classification

II.  Nomenclature = System of naming things

     A.  International Code of Botanical Nomenclature

          1.  Botanical Code independent from Zoological Code

          2.  Application of name determined by types

          3.  Each taxonomic unit can have only one valid name

          4.  Oldest valid name always has precedence

          5.  Names treated as Latin regardless of derivation

          6.  Rules are retroactive from 1753



     B.  Binomial System of Nomenclature

          1. Generic Name 2. Specific Epithet 3. Authority

               Populus        deltoides          Bart. ex Marsh.

          2.  Generic Name

               a.  Always a singular, nominative case noun

               b.  Always capitalized

               c.  May be:

                    1.  Descriptive of some characteristic

                    eg. Liriodendron = lily or tulip tree

                    2.  Aboriginal name

                    eg. Following are Latin 

                         Quercus = oak
                         Fagus = beech
                         Betula = birch

                    3.  Honoring some person

                         Linnaea = Carolus Linnaeus (Carl Linne')



          3.  Specific epithet

               a.  May be:

                    1.  Adjective, agreeing with generic name in
                         gender, usually indicating

                    a.  distinquishing characteristic

                         Rosa alba = white rose

                    b.  where first discovered

                         Ulmus americana = american elm

                    2.  Noun in opposition, always in nominative
                         case, but doesn't have to be same gender
                         as generic name

                         Pyrus malus = apple

                    3.  Noun in genitive singular or plural,
                         honoring a person

                         Carex davisii = honoring Mr. Davis

                    4.  From common name, genitive plural, usually
                         indicating something about habitat

                         Convolvulus sepium = of the hedges


III.  Plant Classification = Arrangement of plant groups in some
     systematic order

     A. Artificial Classification:  order facilitates
          identification of unknown types of plants

     B.  General Purpose Classification:  order reflects general
          genetic relationships and those morphological characters
          that are easy to identify

     C.  Phylogenetic Classification:  order represents the
          degreee to which plant groups have evolved from one
          another or with one another (parallel evolution)

          1.  Often assumed that similarity correlates with recency
               of common ancestory

          2.  Assumed that best genetic relationshipss among groups
               of plants are reflected



IV.  Taxonomic heirarchy = Method of classification of plants in a
     heirarchy or in an order of rank which corrresponds to greater
     and greater degrees of relatedness among members of each rank.

     Kingdom  eg. Plantae = plants 
                      (cellulose cell wall,chlorophyll a and b)

          Division  eg. Magnoliophyta  (Anthophyta) = angiosperms
                         (ovules enclosed in ovary)

               Class  eg.  Magnoliopsida  (Dicotyledonae) = dicots 
                           (two cotyledons)

                    Order eg.  Salicales = willow (simple,
                         alternate leaves with stipules, catkins,
                         pubescent seeds)

                         Family  eg. Salicaceae (leaves deciduous,
                              dioecious, fruit 1 celled 2-4 valved
                              capsule)

                              Genus  eg. Populus (leaves as long as
                                   broad, buds covered by
                                   imbricated scales)

                                   Species eg. Populus deltoides
                                        (deltoid leaves with
                                        compressed petioles and
                                        glandular apices)



V.  What is a species?

     A.  "Recognizable and self-perpetuating population that is
            more or less isolated genetically as well as by its
            geographical distribution and environment"

     B.  Barriers which isolate populations genetically

          1.  Internal

               a.  expressed through incompatibility of gametes or
                    sterile hybrid offspring

               SPECIES A   X   SPECIES B  -->>  No offspring  or,
                                                                 -->> Sterile offspring

               b.  genetic or physiologic in nature

          2.  External

               a.  Environmental

               SPECIES A grows in high mountains
               SPECIES B grows in low river valleys

               b.  Geographic

               SPECIES A grows on west coast
               SPECIES B grows on east coast

               c.  Temporal

               SPECIES A flowers in early spring
               SPECIES B flowers in late fall