Gymnosperms

Seed plants are____? And what do they produce?

heterosporous, that produce megaspores and micro spores that give rise to megagameteophyte and a mircogametophytes

What is the definition of a seed?

A matured ovule,( which is a structure that develops into the seed) that contains the embryo

In seed plants the __ is called the nucellus

Megasporangium

What does the immature ovule consist of?

Megasporanguim, which is the structure in which megaspores are produced by one to two additional layers of tissue(integumments)

What are the events that led up to the evolution of an ovule?

1. Retention of megaspores within a megasporangium, which is fleshy and called the nucellus in seed plants (Megasporanguim no longer releases the spores)

2. Reduction in the number of megaspores mother cells in each Megasporanguim to one

3. Survival of only one of the 4 gametophyte megaspores produced by the mother cells in each, leaving a megaspore in the megasporangium

4. Formation of a female gamtophyte inside a single functional megaspore- female no longer free living and is retained in the Megasporanguim

5. Development of the embryo(young sporophyte) within the female gamtophyte retained in the megasporangium

6. Formation of a integumentary that completely envelops the megasporangium, expect for the opening called the micropyle

7. Modification of the apex of the megasporangium to receive mircospores or pollen grains

Just before fertilization, a gymnosperm ovule contains..?

The nucellus contains a megagametophyte comprised of nutritive tissue and archegonia

With the evolution of the ovule, the unit of dispersal is shifted from the megaspore to the…?

The seed, the embryo containing megasporangium with integuments.

A seed consists of a ___, ___, and a ___.? And how does this occur?

Embryo, stored food and a seed coat.

When the ovules are ready for fertilization the nucellus that contains a megagametophyte that has nutritive tissue and archegonia

After fertilization the integumentary develop a seed coat, the embryo develops within the seed before dispersal

What are the 4 phyla of gymnosperm (seed bearing plants)

Coniferphyta

Cycadophyta,

Gnetophyte

Ginkophyta

What are the characteristics of a Progymnosperms?

Between intermediate between those of seedless vascular trimerophytes and those of seed plants.Produced secondary xylem (wood)

Presence of a Bifacial Vascular cambium ( produced both secondary xylem and phloem and is believed to have evolved first.

A eustele evolved in this group

What is a micropyle

Opening in a Integument, its a formation of a integument that completely envelops themegasporangium

What is the characteristics of Bennetitales- which are an extinct gymnosperms

Mesozoic gymnosperms that disappeared during the Cretaceous

Palm-like leaves that resemble living cycads. Presence of flowerlike reproductive structures that were bisexual in some species

Some believe that are members of the same evolutionary line as angiosperms

In gymnosperms, the microgametophytes develop as what…?

Pollen grains, water is not required from transport the sperm to the eggs, the pollen grain is transferred (by wind) to the vicinity of a megagametophyte within and ovule

What phylum of gymnosperms produce nonmotile sperm?

Coniferphyta and gntophytes

Which group has a pollen tube haustorial?

Cycads and Ginko

After pollination, the endosporic microgametophyte produces a tubular outgrowth called what…?

Pollen tube

Characteristics of Coniferophyta

Numerous and widespread comprise of 70 genera with include 630 species

Tallest Vascular plant redwood

Drought resistant features

Woody plants that have needlelike leaves or scale-like leaves that are often covered in a waxy cuticle

Includes pine, firs, spruces, larches, hemlocks of Pinaeae Crypress and Junipers of Cupressaceae (associated with evergreen)

What are the characteristics of pine leaves?

Arrangement of leaves that is unique among living conifers, needlelike leaves spirally arranged and borne singly on the stems

Shrunken Stomata

After a year or two of growth it Produces its leaves in bundles called facicles, which each contain a specific number of leaves. Surrounded by transfusion tissue

What is the longest lived tree?

The Bristlecone Pine (pines longaeva)

In the pine life cycle, meiosis occurs in the….?

Microsporocytes—> undergo meiosis and produces four haploid micro spores

In pines, the immature gametophyte consists of?

Two prothallus cells, a generative cell and a tube cell

Fascicles in Pine do what?

They are wrapped at the base by a series of small scale like lives, they are short shoots in which the activity of the apical meristem is restricted

Determinate branch(restricted growth)

What is the seed-scale complex of an ovule consist of?

The ovuliferous scale with bears two ovules and a subtending sterile bract

The seeds of pines are often shed when?

The autumn of the second year following the initial appearance of the cones and pollination

In the yews family taxaceae they produce what?

A solidarity ovule is borne in a high reduced cone and a surrounded by a fleshy, cup like structure (Aril)

Which phylum of gymnosperms have palmlike plants that are found in tropical and subtropical regions?

Cycadophyta

Which gymnosperms in a Cycadophyta native to the United States?

Zamia Intergrifolia, native to Florida

In a gneotyphye characterized by two strap shaped leaves growing from a massive woody stem, what species is this?

Welwitschia