Gymnospores Flashcards
Seed plants are called
gymnosperms
the most dominant producers in most terrestrial ecosystems
seed-bearing plants
A seed consists of
an embryo and nutrients surrounded by a protective coat
Shared derived traits of seed plants
- reduced gametophytes
- heterospory
- ovules
- pollen
- seeds
Gametophytes of seed plants develop by
they develop within cell walls of spores that are retained within tissues of parent sporophyte
Sporophyte in non-vascular plants:
independent, dominant gametophyte; sporophyte dependent on the gametophyte
Sporophyte in seedless vascular plants
dominant sporophyte, but gametophyte still independent
Sporophyte in seed plants
sporophyte dominant and independent; gametophyte microscopic and dependent on the sporophyte
Trend: progressive ___ in size and
independence of the gametophyte, and the ___ role of the sporophyte
reduction, increasing
All seed plants are ___ while most seedless plants are homosporous
heterosporous
Heterosporous plants
produce two sizes of spores
two sizes of spores
megaspores and microspores
Microsporangia produce
microspores that give rise to male gametophytes
Megasporangia produce
megaspores that give rise to female gametophytes
Spores are ___ dispersed in seed plants
not
Ovule
consists of a megasporangium (2n), megaspore (1n), and one or more protective integuments (2n). Ovules develop into seeds after fertilization
The megasporangium (2n) produces a megaspore (1n) via
meiosis
Is the megaspore dispersed?
no
Pollination triggers:
development of female (mega) gametophyte (1n)
Microspores develop into
male gametophytes, which are contained
within pollen grains
Pollen grains are coated with
sporopollenin (withstands desiccation, damage, UV)