Introduction to Plants

The classification of plants is subjective. In spite of this, every plant belongs to a species, every species to a genus, every genus to a family, every family to an order, every order to a class and every class to a division. Each of these groups is called a "taxon (plural taxa)." There are more than 350,000 species of plants world wide which have been described. In the state of Idaho there are some 2,800 species of plants. Included in this number are horsetails, ferns, conifers, and flowering plants. Commonly these are referred to as "Higher Plants." These 2800 plants do not include algae, fungi, club mosses, liverworts, etc., Commonly referred to as "lower Plants."

One example of Plant Classification is as follows:

Kingdom Plantae
   Subkingdom I. Prokaryonta
         Division 1. Cyanochloronta
             Class 1. Myxophyceae (blue-green "algae")

Division 2. Schizonta
Class 1. Schizomycetes (bacteria)

Subkingdom II. Chloronta
Division 1A. Chlorophycophyta
Class 1. Chlorphyceae (green algae)

Division 1B. Euglenophycophyta
Class 1. Euglenophyceae (euglenoids)

Division 1C. Phaeophycophyta
Class 1. Phaeophyceae (brown algae)

         Division 1D. Chrysophycophyta
             Class 1. Xanthophyceae (yellow-green algae)
             Class 2. Chrysophyceae (golden-brown algae)
             Class 3. Bacillariophyceae (diatoms)

         Division 1E. Pyrrhophycophyta
             Class 1. Cryptophyceae (cryptomonads)
             Class 2. Dinophyceae (dinoflagellates)

         Division 1F. Rhodophycophyta
             Class 1. Rhodophyceae (red algae)
         Division 2. Charophyta
             Class 1. Charophyceae (stoneworts)
         Division 3. Hepatophyta
             Class 1. Hepatopsida (liverworts)
             Class 2. Anthocerotopsida (horned liverworts)
         Division 4. Bryophyta
             Class 1. Sphagnopsida (peat mosses)
             Class 2. Abdreaeopsida (rock mosses)
             Class 3. Mnionopsida (true or common mosses)
         Division 5. Psilotophyta
             Class 1. Psilotopsida (whisk ferns)
         Division 6. Microphyllophyta
             Class 1. Aglossopsida (eligulate lycopods)
             Class 2. Glossopsida (ligulate lycopods)

         Division 7(F). Arthrophyta
             Class 1. Arthropsida (arthrophytes)
         Division 8. Pterophyta
             Class 1. Eusporangiopsida (Eusporangiate ferns)
             Class 2. Leptosporangiopsida (Leptosporangiate ferns)
         Division 9. Cycadophyta
             Class 1. Cycadopsida (cycads)
             Class 2. Pteridospermopsida (seed ferns)
             Class 3. Cycadeoidopsida (cycadeoids)
        Division 10. Ginkgophyta
             Class 1. Ginkgopsida (Ginkgo and precursors)
         Division 11. Coniferophyta (Pinophyta in other systems)
             Class 1. Coniferopsida (conifers) (Pinopsida in other systems)
             Class 2. Taxopsida (taxads)
         Division 12. Anthophyta (Magnoliophyta in other systems)
             Class 1. Angiospermae (flowering plants) (Magnoliopsida in other systems)

Subkingdom III. Achloronta
         Division 1A. Myxomycota
             Class 1. Myxomycetes (slime molds)
         Division 1B. Acrasiomycota
             Class 1. Acrasiomycetes (cellular slime molds)
         Division 1C. Chytridiomycota
             Class 1. Chytridiomycetes (chytrids)
         Division 1D. Oomycota
             Class 1. Oomycetes (water molds, etc.)
         Division 1E. Zygomycota
             Class 1. Zygomycetes (black molds, etc.)
         Division 1F. Ascomycota
             Class 1. Ascomycetes (sac fungi)
         Division 1G. Basidiomycota
             Class 1. Basidiomycetes (club fungi)
         Division 1H. Deuteromycota
             Class 1. Deuteromycetes (imperfect fungi)

The plants described in this atlas are two of the above groups, the Division 11 Coniferophyta (Pinophyta) and the Division 13 Anthophyta (Magnoliophyta). Two examples of the Division 13 is as follows:

Kingdom	Plantae	Plantae	Plantae
Division	Magnoliophyta	Magnoliophyta	Pinophyta
Class	Magnoliopsida	Magnoliopsida	Pinopsida
Order	Magnoliales	Rosales	Pinales
Family	Magnoliaceae	Hydrangeaceae	Pinaceae
Genus	Magnolia	Philadelphus	Pinus
Specific epithet (species)	grandiflora	lewisii	monticola
Common Name	Magnolia	Syringa or Mock Orange Idaho (The state flower)	White Pine or Western White Pine (the State Tree)

The Class Pinopsida includes mostly trees, such as hemlocks, firs, spruces, larches, and redwoods, but also includes shrubs such as junipers and Japanese yews. Their leaves are simple, often scale-like or needle-like. The leaf bases are not persistent. The wood (xylem) is compact, composed mostly of tracheids, with narrow rays. The pith and cortex are restricted, thus the xylem makes up the majority of the stem. The stem is often differentiated into long portions and short spur shoots. From the stem, the vascular tissue (leaf traces) into the leaf may be one or just a few. The ovules are most often borne in compound cones (strobili) or the ovules may be borne singly.

The pines, or their relatives, may be and often are the dominant type in many forested regions in northern Idaho or in ravines in southern Idaho. Many are valuable for lumber, manufacture of paper, or for naval stores. Some may reach ages up to 4600 years. The leaves are evergreen with the exception of larches, which lose their leaves in the fall. Growth is seasonal and periodic, depending upon temperature and moisture availability. There are two kinds of leaves-the obvious needles and the less obvious scale leaves which occur on the main branches and bases of the needles. The needles in the pines are borne singly in one Idaho species, the singleleaf pinion pine, but most often in 2's, 3's, or 5's. In the other conifers, the needles are borne singly. Moisture loss is prevented by a heavily cutinized epidermis and wax coating. The trunks and branches increase in diameter by cell division in the cambium layer, which is cylindrical. Cross sections of the stems reveal concentric circles caused by thin-walled cells in the spring growth and thicke-walled cells in late season growth. Reproduction results from a combination of pollen produced in small ephemeral cones and ovules produced in the more obvious woody cones. Both occur on the same tree or shrub. The ovules are commonly borne in pairs on the upper surface of the cone scales. Some, because of their large size, are considered edible to humans, such as pinion pine nuts. The seeds of most genera and species are eaten by mammals and birds.

Written by Karl Holte, 2002