Lab 1 ‑ plant identification objectives

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1. To introduce plant nomenclature and classification.

2. To become familiar with basic plant morphology.

3. To begin to identify plants using morphological characteristics.


Plants can be identified by observing certain distinguishing morphological characteristics. Some plants are closely related, which is shown by the similarity of their flower structures. These plants are placed into a specific plant family. A herbaceous example of a family that is based on similarity of flower parts would be Asteraceae, the aster family, of which marigolds and zinnias are members. An example of a woody plant family would be Aceraceae to which maples belong.

Within each family there are members that are more closely related than others. This relationship is demonstrated by the similarity of basic morphological traits like leaf shape or arrangement. These plants are placed in a group called a Genus. Maples belong to the genus Acer while marigolds are placed in the genus Tagetes.
Members of a plant genus are again subdivided, according to their similar morphological characteristics, into a grouping called a species. For example, each different type of maple belongs to a different species (see list below).
The BINOMIAL PLANT CLASSIFICATION SYSTEM, which we have just described, gives each plant a scientific name using the genus and species.
Examples of scientific names:
Scientific Name Common Name
Acer saccharinum Silver Maple

Acer platanoides Norway Maple

Tagetes erecta African Marigold

Tagetes patula French Marigold
When botanists group plants, they use flower parts as their primary guide because the flower is the least affected by growing conditions. In this lab we will be looking at leaf characteristics to help us identify plants because they are more likely to be available to you.
Introductory Lecture Outline

A. Plant Nomenclature

1. Binomial classification system

a. two Latin names



b. cultivars and varieties.

c. importance
B. Morphological Characteristics
1. Plant type

a. Woody

1. deciduous

2. evergreen

b. Herbaceous

1. annual

2. perennial

3. biennial

2. Leaf type (we will study this in detail in lab)

3. Fruit type

a. samara

b. pome

c. nut‑like

d. cone

e. acorn (nut)
4. Flowers are borne on structures called inflorescences, which are a collection of individual flowers arranged in a specific order or way.

a. spike (a catkin is a type of spike ex. pussywillow)

b. raceme

c. corymb

d. umbel

e. cyme

f. panicle

g. solitary

  1. head

5. Other characteristics

In order to successfully identify woody plants it is necessary for an individual to have a keen awareness (working knowledge) of taxonomic terminology and concise mental pictures of leaf, bud, stem, flower and
fruit morphology.


Simple Leaf Pinnately Compound Leaf
The position of the bud determines whether the leaf is simple or compound. In the case of the single leaf the bud is found in the axil of the leaf and stem. If the bud is located in the axil of a structure containing more than one leaf it is termed compound. Compound leaves may have from three to 1500 leaflets. Ex: Acer with three or Albizia julibrissin with 400 to 1500 leaflets.

Palmately Compound Odd Pinnate Even Pinnate

Ex: Acanthopanax, Parthenocissus Ex: Acer negundo, Fraxinus Ex: Gleditsia

Bipinnately Compound
Bipinnately compound leaves are twice divided. What was considered the leaflet of the pinnately compound leaf is now another leaf-bearing axis to which additional leaflets are attached. The new leaf bearing axes are referred to as pinnae. Each pinna has a certain number of leaflets. Ex: Gymnocladus, Albizia, Gleditsia (in certain instances).

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