Objectives:
1. Describe adaptations of vascular plants, including modifications of the lifecycle and of the sporophyte, that have contributed to their success on land.
2. Distinguish between homosporous and heterosporous
3. Distinguish among spore, sporophyte, sporophyll and sporangium
4. Diagram the life cycle of a fern including spore production, gamete production and fertilization.
5. Distinguish between the 4 divisions of seedless plants from one another.

Adaptations of vascular plants:
A. Specialization of the plant body

a. Subterranean root systems which absorb water and minerals

b. Aerial shoot systems of stems and leaves for photosynthesis
 

B. Lignin provides structural support
        * As opposed to aquatic environments, plants in terrestrial environments need structural support to stand upright in the air.

        *This is provided by the hard material lignin embedded into the cellulose matrix of cell walls.

C. Vascular system with two types of conducting tissues

Vascular tissue consisting of tubular chains of cells transports materials between distant organs of the plant.
 
 

Xylem
        * conducts water and minerals from the roots to the rest of the plant

        * composed of dead, tube-shaped cells that form a microscopic water-pipe system

        * have lignified cell walls, giving the plant structural support

Phloem
        * Conducts food throughout the plant body

        * Composed of living cells arranged in tubes

        * Distributes sugars, amino acids, and other organic nutrients

D. Pollen. Pollination eliminates the need for water for transport of gametes in gymnosperms and angiosperms

E. seeds are produced by gymnosperms and angiosperms

F. sporophyte is the dominant stage in the life cycle.

Ferns have large leaves (megaphylls) with a branched system of veins.

The sporophyte is the dominant stage of the life cycle

It consists of
        a. fronds: compound leaves that are divided into several leaflets

        b. rhizome: underground stems

        c. adventitious roots that arise along the rhizome

The emerging frond is first of all coiled into a fiddlehead that unfolds as it grows.

When the fronds have expanded small, often circular patches of powdery material may appear on the lower surfaces of the blades =Sporangia.

Sporangia generally found in clusters called sori.

While developing, sori are generally protected by thin flaps of colorless tissue called indusia (indusium, singular).

Spore mother cells undergo meiosis producing 48 to 64 spores per sporangium.

A single fern plant can produce up to 50 million spores as the number of sporangia on a fern plant can be great!!!!!

        * A single type of spore is produced in most ferns homosporous condition

        * In a few species megaspores and microspores are produced heterosporous condition

Spores are dispersed by wind and germinate in favorable locations.

The green heart shaped gametophytes that develop are called prothalli (singular prothallus).

The four divisions of the seedless vascular plants and a few characteristics

        *Division Pterophyta (ferns)

        *Division Lycophyta (club mosses and quillworts) Selaginella and Lycopodium

Stems of these plants are covered with microphylls -leaves with a single vein.

Strobili at tips of sporophyte

        *Division Psilotophyta (whisk ferns)

Absence of true leaves and roots

Homosporous life cycle, similar ferns

        *Division Sphenophyta (horsetails)
Homosporous

 Have ribbed stems containing silica deposits, very few predators

Equisetum meiospores have chloropasts

Elaters part of meiospore walls used for wind dispersal