4: Gymnosperms (4/9) Flashcards
What is one unifying factor among all gymnosperms and what does it mean?
All gymnosperms are heterosporous, meaning they produce two distinct types of spores: megaspores and microspores
They’re also all seed-producing plants
What do megaspores and microspores develop into?
Megaspores –> ovules
Microspores –> pollen grains
Pollen cone
The male reproductive structure of gymnosperms responsible for producing and releasing pollen
Ovulate (seed) cone
The female reproductive structure of gymnosperms where megaspores develop, get fertilized, and eventually form seeds
Cone scale
A flat, plate-like structure that makes up the body of an ovulate (female) cone
Aril
A fleshy, often colorful outgrowth that partially or completely covers a seed. Grows from the base of a seed
Decurrent leaf base
Leaf base is adherent to the stem for some distance
Approximately how long ago were these groups believed to have originated?
- Green plants
- Land plants
- Vascular plants
- Seed plants
- Angiosperms
- Green plants: ~1,000-750 mya
- Land plants: ~460 mya
- Vascular plants: ~420-430 mya
- Seed plants: ~360-385 mya
- Angiosperms: ~145 mya
Diagram the life cycle termed heterosporous alternation of generations in generalized form and with specific reference to angiosperms
Microsporangia (in anthers) produce microspores, which develop into male gametophytes (pollen grains containing sperm cells).
Megasporangia (in ovules) produce megaspores, which develop into female gametophytes (embryo sacs containing egg cells).
The male gametophyte delivers sperm to the egg in the female gametophyte, resulting in fertilization and the formation of a diploid zygote, which grows into a new sporophyte
Eustele
A type of vascular tissue arrangement where the vascular bundles are arranged in a ring around the central pith of the stem
Vascular cambium
Layer of meristematic tissue between the xylem and phloem that is responsible for secondary growth
Cork cambium
Type of lateral meristem that forms in woody plants, producing cork cells that form the outer bark
Periderm
The protective outer layer that forms in the stems and roots of woody plants
Gametophyte
The haploid, multicellular phase of the plant life cycle that produces gametes (sperm or eggs) by mitosis
Endosporic male gametophyte
A microspore that develops within its own spore wall to form an endosporic male gametophyte, known as a pollen grain
Becomes a pollen grain once it starts developing
Antheridia
What kind of plants are they found in?
The multicellular structures typically responsible for producing sperm in many non-seed plants
Found in lycophytes, monilophytes, and some gymnosperms (not angiosperms)
Male gametophyte lacking antheridia
Male reproductive structure in certain plants (especially in seed plants) that does not produce antheridia
In seed plants
Endosporic female gametophyte
A megaspore that develops within its own spore wall to form a female gametophyte, known as the embryo sac in flowering plants
Integument
One or more layers of protective tissue that surrounds the ovule; after fertilization, the integuments develop into the seed coat
3-nucleate male gametophyte
What group is it exclusive to?
Male gametophyte (pollen grain) that contains three nuclei
This term is commonly used to describe the structure of the male gametophyte in angiosperms
Ovule with 2 integuments
Ovule in which there are two protective layers (integuments) surrounding the female gametophyte
Archegonium
What kind of plants are they found in?
A multicellular structure that houses the egg cell and is the site where fertilization occurs
Found in lycophytes, monilophites, and gymnosperms (NOT angiosperms)
Reduced female gametophyte lacking archegonia
What kind of plants are they found in?
A female gametophyte (which produces the egg cell for fertilization) that does not contain archegonia
Only angiosperms
Double fertilization
A unique feature of angiosperms (flowering plants) in which two fertilization events occur during the process of sexual reproduction
