Vascular Plant Morphology
Introduction:

Gymnosperms:

Angiosperms:
     Dicots
     Monocots

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Introduction:
The morphology of a plant deals with the external structures of a plant.  For example, what kind of root system does the plant have, or how are the leaves arranged along the stem.  Within the basic morphology of a plant one can see many adaptations that have allowed plants to live in terrestrial environments.  Keep in mind as you work your way through this material that the ancestors of plants were algae which lived in aquatic habitats.

Gymnosperms:
Gymnosperms are characterized by the "naked"ovule that is exposed to the air at the time of pollination.  Angiosperms, on the other hand, have ovules that are protected by the carpel wall.  The mature ovule is the seed, whose evolution came about due to heterospory (formation of two different spores).  There are five phyla that make up the Gymnosperms: Pteridospermophyta (seed ferns), Cycadeoidophyta (cycadeoids),  Cycadophyta (cycads),Ginkgophyta (Ginkgo), and Coniferophyta (conifers). 

Angiosperms:
Angiosperms are characterized by fruits and flowers.  These are adaptations that function in reproduction and seed dispersal.  There are approximately 275,000 know angiosperm species, which makes this plant group the most diverse and widespread.   The angiosperms are split into two classes: the monocotyledons (monocots) and dicotyledons (dicots).  The monocots are characterized by having a single cotyledon (seed leaf), while the dicots are characterized by having two cotyledons.  There are several other morphological characteristics that are similar to each class which will be described below. 
 
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 Dicots:
Dicots can be herbaceous or woody plants.  The vascular bundles in their stems are arranged in in a ring around a small pith.  The vascular cambium produces secondary xylem toward the interior of the stem, and secondary phloem toward the outside of the stem.  Dicot leaves display a netted reticulate venation pattern that can be either palmate or pinnate.  The dicot flower parts will be in multiples of four or five.  The embryo will have two cotyledons.  Some examples of dicots are: magnolias, oaks, beeches, willows, maples, asters, zinnias, marigolds, cacti, jade plant , tomatoes and potatoes, poison ivy, cotton, blueberries, and rhododendrons
 
 
 
 

Monocots:
Monocots tend to be herbs, but can occasionally be woody.  The vascular bundles in their stems are scattered.  Their leaves have major veins that run in parallel, and almost always have smooth leaf margins.  The flower parts are fund in multiples of three.  The embryo will have only one cotyledon.  Some examples of monocots are: grasses (wheat, oats, corn, and rice), sedges, lilies, irises, palms, orchids, and bananas.

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