vasuclar plants - pteridophytes Flashcards
what are the two types of vascular plants
1) seedless
2) plants which produce seeds
what is the dominant generation in vascular plants
sporophyte generation as it lives independently of the gametophyte
what are the main classifications of seedless vascular plants
1) psilophyta
2) club mosses
3) horse tails
4) true ferns
outline the characteristics of early vascular plants
- dichotomously branched stems
- sporangia produced at the end of branches
- simple vascular bundles
- epidermis with cuticles
- homosporus - produce only one type of spore
what is a psilophyta
- simplest extant vascular plant
- upright branches
- sporangia produces at the ends of branches
- gametophyte has a vascular system
outline characteristics of ture ferns
- epiphytes
- homosporous
- presence of rhizomes
what is a rhizome
a continuously growing underground stem which puts out lateral shoots and adventitious roots
where are fern sporangia located
clustered on the underside of leaves in a sorus
define sorus
a cluster of spores/ sporangia
what is an indusium
a membraneous growth of the epidermis that covers sorus and helps protect developing sporangia
outline the life cycle of ferns
1) wihtin the sorus spores undergo meiosis producing the gametophyte generation= prothallus
2) these are fertilised becoming a diploid sporophyte
outline the structure of a prothallus
- a gametophyte
the antheridia found on the outer regions
the archegonia found in the middle region
what is a disadvantage of the fern lifecycle
- ## new sporophyte is temporally dependant on the gametophyte at the start of life
what is one way to improve the survival of young sporophytes
- if the embryo could derive nourishment from mother sporophyte rather than living separate life as a gametophyte ie develops within the sporangium
