Chapter 30: Plant diversity (seed plants) (1) Flashcards
What features are common to all seed plants?
In addition to seeds, the following are common to all seed plants:
– reduced gametophytes
– heterospory
– ovules
– pollen
POHR
How are the gametophytes of seed plants?
The gametophytes of seed plants develop within the walls of spores that are retained within tissues of parent sporophyte
What does an ovule consist of?
An ovule consists of a
– megasporangium
– megaspore and
– one or more protective
integuments
How many integuments are present in gymnosperm and angiosperm megaspores?
Gymnosperm megaspores have
one integument
* Angiosperm megaspores usually
have two integuments
what is the dominant life stage in seed plants?
sporophyte
What is the advantage of pollen?
Pollen eliminates the need for a film of water and can be dispersed to great distances by air or animal.
A seed is a ________ embryo, along with its food supply, packaged in a protective coat
A seed is a sporophyte embryo, along with its food supply, packaged in a protective coat
What are the advantages provided by seeds?
- they may remain dormant for days to years, until conditions are favorable for germination
– seeds have a supply of stored food
– they may be transported long distances by wind or animals
Gymnosperms means _________.The seeds are exposed on _______ that form cones. Most gymnosperms are cone-bearing plants called __________.
Gymnosperms means “naked seeds”.The seeds are exposed on sporophylls that form cones. Most gymnosperms are cone-bearing plants called conifers
What are the 3 key features of the gymnosperm life cycle?
Three key features of the gymnosperm life cycle are
– dominance of the sporophyte generation
– development of seeds from fertilized ovules
– transfer of sperm to ovules by pollen
____________ began to replace gymnosperms near the end of the Mesozoic era. _______ now dominate most terrestrial ecosystems
Angiosperms
What are the 4 phyla in gymnosperms?
The gymnosperms consist of four phyla:
– Cycadophyta (cycads)
– Gingkophyta (one living species: Ginkgo biloba)
– Gnetophyta (three genera: Gnetum, Ephedra, Welwitschia)
– Coniferophyta (conifers, such as pine, fir, and redwood
What are cycads?
- Cycads thrived during Mesozoic,
(i.e. the age of the cycads/ dinosaurs)
– relatively few species exist today - Individuals have large cones and
palmlike leaves
Which gymnosperm phyla has flagellated sperm?
Cycads and ginkgos
Which phylum is a popular ornamental tree that has a high tolerance for pollution?
Gingko
What are the characteristics of ginkgo?
Ginkgo biloba is the only surviving
species
– Ginkgo biloba has deciduous
fanlike leaves that turn gold in
autumn.
* Like cycads, has flagellated sperm
* A popular ornamental tree that has
high tolerance for air pollution
What are the characteristics of gnetophyta?
This phylum comprises
three genera:
– Gnetum
– Ephedra and
– Welwitschia
- Species vary in appearance, and some are
– tropical
– others live in deserts
What are the facts of gnetum?
- Genus includes trees mainly native
to Africa and Asia - Leaves are similar to those of
flowering plants - Seeds look somewhat like fruits
What are the facts of ephedra?
Genus consists of about 40 species that inhabit arid regionsworldwide.
- Ex. includes desert shrubs commonly called “Mormon tea” that produce the compound ephedrine.
- Ephedrine is used medically as a decongestant
What are the facts of welwitschia?
Genus consists of one species Welwitschia mirabilis
- The plant has distinctive large
strap-like leaves
– Leaves are among the largest
known plant leaves
- The plant can live for thousands
of years
