Seedless Vascular Plants Flashcards
Earliest vascular plant fossils date to
425 mya
Early vascular plants are called
aglaophyton
Aglaophyton had anatomical features intermediate between _____ and _____
bryophytes and vascular plants
Shared derived traits of vascular plants
vascular tissue, life cycles with dominant sporophytes, well-developed roots and leaves
Vascular tissue evolved only in _____ of vascular plants
sporophytes
Gametophytes lack ____
vascular tissue
Vascular tissue allows sporophytes to
grow tall
xylem
conducts water and minerals via dead, hollow cells that form continuous conduits throughout the plant. The Water-conducting cells are strengthened by lignin.
Phloem
consists of living cells and distributes nutrients and organic products
Sporophyte dominate in:
size, complexity, and persistence
The benefit of multicellular leaves
increase the surface area of vascular plant sporophytes (capture more light for photosynthesis)
The benefit of multicellular roots
anchor vascular plant sporophytes, enable vascular plants to absorb and transport water and nutrients from the soil.
Types of vascular plant leaves
− Microphylls
− Megaphylls
Microphylls
small leaves with a single vein, may have evolved as outgrowths of stems
Megaphyllys
large leaves with the highly branched vascular system, may have evolved as webbing between flattened branches
Sporophylls
modified leaves bearing sporangia (spore-producing organ)
Sori
clusters of sporangia on the undersides of sporophylls
Strobili
cone-like structures formed from groups of sporophylls
Homosporous sporophytes
producing one type of spore that develops into a bisexual gametophyte (most seedless vascular plants are homosporous)
All seed plants and a few seedless vascular plants are:
heterosporous
Sporophytes of heterosporous taxa
produce
megaspores, which give rise to female gametophytes, and microspores, which give rise to male gametophytes
flagellated sperm
In seedless vascular plants, sperm must swim in a film of water to reach eggs (fertilization requires water)
The sporophyte is ___ in seedless vascular plants
dominant
two clades (phylum) of seedless vascular plants
Lycophyta (mosses and quillworts) and monilophyta (ferns, horsetails, and whisk ferns)
Lycophytes
- small herbaceous plants
- microphyllous
- homo or heterosporous
3 Taxa in Monilophytes
whisk ferns, horsetails, and ferns
Whisk ferns
- resemble ancestral vascular plants but are closely related to modern ferns
- no root or leaves
Horsetails
- bushy stems
- Horsetails have leaves with a single vein
- secondarily microphyllous (2° simplification of ancestral complex leaf) venation
Ferns
- most diverse seedless vascular plants
- diverse in tropics, and temperate forests
- have megaphylls (large leaves with branched vascular systems)
- produce clusters of sporangia (sori) on undersides of leaves
- most are homosporous
Ancestors of extant lycophytes, horsetails, and ferns dominated during the:
Devonian and Carboniferous (forming first forests)
Partially decayed plant material of Carboniferous forests eventually formed rock strata called
coal
Increased plant growth and photosynthesis may have caused
global cooling by removal of CO2
