I. Introduction
    These are plants with tissues specialized for conduction and support. This means that they have true roots, stems and leaves.

II. Organization of Vascular Plant Structure

A. Organs and Systems
1. Roots - the root system serves primarily for anchorage and absorption.
2. Stems and leaves - shoot system. Stems support the photosynthetic leaves, and conduct raw materials toward and products from them.
B. Tissues and Growth
1. Primary tissues are laid down by primary growth. This is growth from the apical meristems. Meristems are the highly mitotic regions near the apices of roots and stems. Simple vascular plants have only primary tissues, as do many advanced species. The three primary tissues are:
a. Protoderm - gives rise to epidermis
b. Procambium - vascular tissue - xylem and phloem - stele.
c. Ground meristem - parenchyma and pith - cortex.
2. Secondary tissues are laid down by secondary growth. This is done by vascular cambium - lateral meristem. Vascular cambium lays down secondary xylem and secondary phloem. Cork cambium may also be active and produce periderm. This may replace the epidermis as the outer layer of the plant.
C. Steles
    Primary vascular tissues - xylem and phloem (and pith) form the stele or central cylinder. The form of the stele is variable.
1. Protostele
    This is the simplest form, consisting of a solid strand of xylem surrounded by, or interspersed with phloem. This stele is found in Psilophyta, Lycophyta, and roots of many other plants.
2. Siphonostele
    Tubular, with pith surrounded by xylem and phloem. The cylinders are often broken by leaf gaps where leaf traces go out to the leaves. There are two basic forms of siphonostele.
a. Ectophloic - Phloem is outside of the xylem.
b. Amphiphloic - Phloem inside and outside of the xylem cylinder. Often seen in ferns. Leaves often have leaf traces with leaf gaps.
c. Dictyostele - Essentially a dissected siphonostele.
3. Plectosteles - highly dissected
4. Eusteles - Separate bundles around a central pith.
5. Atactostele - irregular arrangement of bundles - as in Monocots. Often have "monkey-face" appearance.
D. Cells
1. Sieve elements - Phloem - Softer cells than xylem
a. Sieve cells - have nuclei - seen in simpler plants
b. Sieve tubes - no nucleus, but have associated companion cells with nuclei.
2. Tracheary elements - Xylem
a. Tracheids - for support, and conduction of water. Lignified.
b. Vessel cells
E. Leaf types
1. Microphylls - usually small, with single strand of vascular tissues. Usually lack leaf gaps at origin of leaf traces.
2. Megaphylls - usually larger, with system of veins. Usually show leaf gaps with the leaf traces.

A. Homospory - one type of spore formed. Meiosis -> one type of spore which forms monoecious gametophytes.
Found in Psilophyta, some Lycophyta, Arthrophyta/Sphenopsida, and most Pteridophyta/Filicophyta.
B. Heterospory - 2 types of spores. Development of spores os endosporal.
1. Microspores from microsporangia produce male gametophytes
2. Megaspores from megasporangia produce female gametophytes.
Found in some Lycophyta, a few Pterophyta/Filicophyta, and all seed plants. Equisetum is interesting in that it exhibits homospory, but physiologically is heterosporous, with dioecious gametophytes.
C. Gametophytes -
Homosporous plants have rather large gametophytes which are independent of the sporophyte. Some are heterotrophic, depending upon mycorrhizal fungi. Others are photosynthetic.
Archegonia are found in most vascular plants other than angiosperms.
Antheridia are lacking in the seed plants (gymnosperms and angiosperms).
Seeds are an embryo, food supply, and enclosing seed coat.
 

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