Science Articles

General Introduction to Botany and Plants

Humans are dependent on understanding and using plants either directly or indirectly for almost all of our needs such as food, clothing, fuel, vitamins and antibiotics.

The Plant Kingdom consists of 350,000 known species. There are new species found everyday.

Two major Groups of Plants

Plants can be categorized in two major groups:
Group 1 - without conducting tissues, which includes 20,000 algae, 90,000 bacteria and 23,000 moss and liverworts.
    
Group 2 plants have conducting tissues:
a) 7,000 plants including ferns, club moss, and horsetails which do not have seeds
b) The largest group of plants (200,000) has both conducting tissue and seeds.  It is divided again into plants with cones - conifers (Gymnosperms) 'evergreens' and plants with flowers (Angiosperms).

Conifers / Gymnosperms
Conifers generally have cones, are evergreen and have needles.  The exceptions are the deciduous (drop their needles) conifers like the larch,  and those which have leaves and not needles - Gingko, cycads, Gnetum. Not all evergreens are conifers.

Flowering or Angiosperms
The flowering plants get divided again into monocots and dicots. The 'cot' part comes from the first leaves that come out of the seed, the 'seed leaf'.  Monocots have only one and dicots have two.

Monocots and Dicots

1. Monocot examples include grasses, lilies, iris, and orchids.  Their characteristics include:
    1.  1 cotyledon (seed leaf)
    2. leaf veins parallel
    3. flowers in 3s
    4. vascular bundles - scattered, cylinder of pith
    5. no cambium

2. Dicots are the larger and more diverse group. And include beans, peas, maples, tomatoes, and zinnias
    1. 2 cotyledons
    2. net veins in the leaves
    3. flower - 4/5 parts
    4. vascular bundle arranged in cylinder
    5. cambium

Annuals, biennials and perennials

All of the plants from every group can be categorized by their growing patterns.  These patterns shift with climate, too.  What may be an annual in cold climate could be a perennial in warmer areas.  Remember 'house plants' grow wild somewhere. There are no hard lines here.  Annuals and biennials seed once, perennials can seed usually once a year and live from a few to hundreds of years.   There are two types of Perennials, woody and herbaceous.  Trees and shrubs are woody.  Herbaceous plants may lose their soft annual growth, but the roots remain viable.  Examples are asparagus and iris.