Final Exam Flashcards
1
Q
the bryophytes
A
Phylum Hepatophyta (Liverworts)
Phylum Anthocerotophyta (Hornworts)
Phylum Bryophyta (Mosses)
- Gametophyte stage dominant; dioecious; thallose and leafy forms
- Sporophyte stage attached to gametophyte
- Low to mid level of tissue differentiation
- No tracheids; leaves simple
- Small size
- Earliest members of land plants
- High humidity/access to water important
- Mosses common in forests, edge of fields
- movement to land was accompanied by the two multicellular generations: one specialized for fertilization and the other for dispersal
2
Q
fertilization and dispersal
A
-all have water fertilization and air dispersal minus a select few
Water fertilization and water dispersal:
-green algae and most closely related to green algae
Air fertilization and air dispersal:
-gymnosperms
-angiosperms
3
Q
byrophyte sporophyte
A
- Bryophyte sporophyte stage grows from the gametophyte
- Sporophytes receive water and nutrients from the gametophyte
- Sporangium is the organ producing meiospores for wind dispersal
4
Q
byrophyte phylogeny
A
- Bryophytes are paraphyletic and form a phylogenetic grade below vascular plants
- Mosses are sister group to the vascular plants
5
Q
summary of the three byrophytes
A
Liverworts, Phylum Hepatophyta,
- include the most primitive plants and range from forms with dichotomously branching thalli (ca 1000 spp) to leafy moss-like forms (ca 8000 spp)
Hornworts, Phylum Anthoceratophyta,
- are a small group ( ca 500 spp) with multilobed flattened thalli and elongated narrow sporangia (shaped like horns of some antelope)
Mosses, Phylum Bryophyta
- in the narrow sense, include a large number of small leafy plants (ca 14,500 spp) producing sporangia with a central sterile column. Mosses differ greatly in colour, stem and leaf traits, habit orientation and habitat preferences
6
Q
life cycle of liverwort
A
diploid
-saprophytic
fertilization –> zygote –> sporophyte with sporangium –> meiosis within sporangium
haploid
-gametophytic
spores released –> archegonium or antheridium forms –> sperm fertilizes egg
7
Q
phylum byrophyta (mosses)
A
- Gametophyte stage dominant; dioecious
- Sporangium has central column
- Low to mid level of tissue differentiation
– Mostly no tracheids, but some conductive tissue differentiation
– Leaves simple to somewhat differentiated into tissues
– Small size - 14,500 spp
8
Q
life cycle of moss
A
diploid
fertilization –> sporophyte/ sporangium supported by gametophyte –> meiosis
haploid
haploid spores –> dispersal –> gametophyte –> sperm release –> fertilization
9
Q
peat moss (sphagnum)
A
- Peat moss is ecologically and economically valuable
- Leaves are one cell thick and have two kinds of cells
- Live photosynthetic cells
- Dead water-storage cells
- Peat mosses lower the pH to 4.5 preventing decay; peat bogs are unique habitats
- Packets of peat were used in folk medicine and in feminine hygiene pads
- Peat is harvested from dried bogs and used in the horticulture business.
- Addition of peat to southern Ontario soils greatly improves their water retention and lowers the pH
10
Q
kettle bogs
A
- Kettle bogs are deep depressions filled
with dead peat that can be many m thick - They form when blocks of glacial ice
are left behind surrounded by sand
and gravel - The surface mat is not solid and you
can bounce on it
11
Q
tracheophytes
A
- Silurian period (~419-444 mybp)
- Xylem present in fossil record from mid-Silurian
- “forests” at the time were bryophytes and early vascular plants along the edges of water
- Became much more widespread into the Devonian (420-360 mybp)
- No leaves or roots
- Sporangia at terminal end of dichotomously branching stems
- Some likely gave rise to ferns & seed plants
- Vascular Plants aka. plants with plumbing
- Synapomorphy
- Tracheids
- vascular tissue -(xylem and phloem)
- Dominant free-living sporophyte
- Same basic life cycle among all vascular plants despite incredible diversity
- Divided into three groups for convenience
- Fern Allies
- Ferns
- Seed Plants
12
Q
anatomy of vascular plants
A
- Vascular plant stems have a number of basic tissue types
- Vascular tissues lie in a ring near the outside of the stem
- Extends from tip of the roots through the stem and into veins within leaves
13
Q
xylem
A
- Xylem cells carry water and dissolved nutrients from the roots to the shoots; tracheids = primary cell type; vessels are more specialized; both are dead cells
14
Q
phloem
A
Phloem carries photosynthates, hormones and other materials to all parts of the plant
15
Q
trends in life cycles
A
- shift from dominant haploids to dominant diploids
- shift in the need for free water for fertilization
- development of vasculature
16
Q
nomenclature of tracheophytes
A
- Although many different classification schemes have been proposed, most textbooks recognize about 15 Phyla of living and extinct tracheophytes
- Some schemes recognize just one Phylum Tracheophyta, as is done in Biol 165
- DNA sequence studies and cladistic analyses have led to significant revisions in thinking about relationships among groups of vascular plants, particular among the fern allies
- Rhyniophyta is paraphyletic with different orders being basal to other groups
17
Q
early vascular plants (all extinct)
A
- Earliest vascular plants underwent dramatic divergence in the Devonian
- The Rhyniophyte Grade
- the most primitive vascular plants dichotomously branching stems terminal simple sporangia or synangia
- Subph. Lycophytina Class Zosterophyllopsida
- overtopping, dichotomous branching sessile sporangia on lateral or main stems
- Trimerophyte Grade
- basal to Subph. Euphyllophytina overtopping, dichotomous branching terminal sporangia on lateral branches
- Through the Devonian, the terrestrial surface of the Earth became green
- “mossy forests” gave way to shrub-like forests (<1m tall), moving inland from water sources
- Lycophytes, horsetails and ancestors of modern seed plants are common
- Plants now have roots, leaves and grow tall – have woody tissues –> 1st trees
18
Q
lycophytes, ferns, horsetails
A
- The lycophytes and the ferns and horsetails are the first two lineages of vascular plants.
- Both depend on swimming sperm for fertilization and disperse by spores that are released into the air
- Lycophytes and ferns are dissimilar to bryophytes as both gametophyte/sporophyte generation is free-living and produces its own nutrients
- more primitive kinds of extant (living) vascular plants; all groups first appeared in the upper Devonian Period
- All living species have small sporophytes except for some kinds of ferns and some fossil fern allies
- Lycophyte fern allies are microphyllous; monilophyte ferns and horsetails are megaphyllous
- Spores are produced in large thick-walled sporangia (eusporangiate), except in some orders of ferns
- The gametophytes are small and free-living (= sporophyte dominant)
19
Q
leaves
A
- Leaves are organs of plants adapted for photosynthesis
- Microphylls are simple out-growths of the stem and have a simple vasculature
- Megaphylls are really modified branching systems and have a complex vasculature; these are highly varied
20
Q
fern allies
A
- All living species are small except for a few tree ferns
- Are intermixed phylogenetically (only recently agreed to form a monophyletic group)
21
Q
fossils of fern allies
A
- Fossil genera in several Classes were large tree- sized plants that formed the co-dominant vegetation of forest ecosystems throughout the world during the Carboniferous Period (350-280 mybp)
- Carboniferous Period plants formed vast coal deposits that are mined today
22
Q
lycophyta or lycopsids
A
- The extant Class Lycopsida includes ground pines, ground cedars, club mosses, spike mosses, quillworts and all their fossil relatives
- All have kidney bean-shaped sporangia
- All extant lycophytes are small herbaceous perennial plants, but some Carboniferous members were large tree-sized plants with secondary growth
- Sporangia are eusporangiate (thick walled), borne on leaves (sporophylls) that are usually grouped into cones (strobili)
- Gametophytes are often cylindrical and subterranean and live in a symbiotic relationship with fungi
23
Q
lycophytes hetero vs homo spory
A
- Some lycophytes are homosporous (one kind of spore);
- Some are heterosporous (two kinds of sporangia & spores)
- Heterosporous taxa have unisexual (dioecious) gametophytes that develop inside the spore wall (endosporal)
24
Q
life cycle of lycopodium
A
tetrad of spores –> gametophyte –> fertilization in archegonium –> sporophyte –> strobilus –> meiosis
25
Q
life cycle of selanginella
A
meiosis forms micro and mega spore –> mature male gametophyte forms from microspore and releases sperm –> sperm fertilize megaspore –> zygote –> sporophyte –> strobilus
26
Q
Subphylum Euphyllophytina
A
- All megaphyllous vascular plants
- Ferns and some ”fern allies (Moniliforms)
- Seed Plants and ancestors (Lignophytes)
- Seed Ferns
- Cycads
- Gingko
- Conifers (pines, firs, spruces, etc.)
- Gnetophytes
- Flowering Plants
27
Q
horsetails
A
- Small herbaceous plants with reduced leaves and no secondary growth; only ca 25 living spp. of Equisetum
- Living species have homosporous sporangia borne in strobili with whorls of branches; spores are large and green; gametophytes are free-living and leafy-lobed
28
Q
horsetail stems
A
- Leaves and branches are arranged in whorls; stems are distinctly jointed (node-internode difference); most have hollow internodes
29
Q
life cycle of equisetum (horsetail)
A
jumping spore –> bisexual gametophyte –> fertilization –> adult sporophyte –> meiosis
30
Q
horsetail fossils
A
- Fossils species were small woody-stemmed plants to large tree-sized plants with secondary growth; both common in Carboniferous Period
- Calamites was a woody tree-sized horsetail common in the Carboniferous Period
31
Q
traditional ferns
A
- All ferns traditionally were members of the Division/Phylum Pteridophyta (a.k.a, Polypodiophyta); there are about 15,000 spp of extant ferns; most are tropical
- Ferns have a rich fossil record going back to the late Devonian
- Mostly when you look at a fern you see megaphyllous leaves (called fronds in technical “fern terminology”)
32
Q
fern stems
A
- Ferns lack secondary growth and usually have short stems oriented either vertically or horizontally
- tree ferns and a few other tropical species have larger stems up to a 1 m in diameter and 3-10 m tall
- tree ferns are held up by their bark with persistent frond bases and adven-titious roots forming a sheath around the trunk
33
Q
fern leaves (fronds)
A
- Ferns leaves can be simple or compound, the compound leaves can be divided 1-6 times
- Size ranges from a 0.5 mm to 6 m
34
Q
fern sporangia and sori
A
- Ferns sporophytes produce spores in sporangia borne in clusters called sori on the under side of the blade or borne on fertile leaflets
- The size, shape and position of sori are used to classify genera and species of ferns
- Some sori have a protective covering (indusium); variation in indusium shape and point of attachment are also used in classifying and identify ferns
- Most ferns are homosporous; two Orders produce eusporangiate sporangia and three produce leptosporangia sporangia (which are smaller, thin walled and produce fewer spores)
35
Q
life cycle of a fern
A
diploid
fertilization –> sporophyte (nutrients from gametophyte) –> sporangia on leaves –> meiosis
haploid
spores –> dispersal –> gametophyte –> sperm released towards egg
36
Q
basic stem anatomy
A
- vascular plant stems have a number of basic tissue types
- the oldest vascular plants had simple stems
- seed plants have the most complex in terms of numbers of specialized kinds of cells
- A plant that must grow in diameter to grow tall
- An increase in a plant’s diameter is referred to as secondary growth
37
Q
the first seed tree
A
- Near the end of the Devonian Period (355 mybp) a new kind of plant evolved for the first time, the tree.
- The first trees were “experiments” combining wood and growth features like conifers with fern-like reproductive structures.
- These first trees are treated as progymno- sperms, the earliest members of the lignophyte clade
38
Q
seed plants
A
- Seed plants include gymnosperms (seed ferns, cycads, ginkgos, conifers, gnetophytes and fossil relatives) and angiosperms (flowering plants)
- Seed plants are the dominant group of plants on the planet today and have been for the last 230 or so million years
- Seeds plants are heterosporous; the female gametophyte is retained within the sporophyte and is never free-living
39
Q
seeds
A
- A seed is a post-fertilization ovule, which is the protective sporophyte tissue layer(s) that surround(s) the megasporangium, the female gametophyte and the embryonic next-generation sporophyte
40
Q
a seed is a little plant in a box with its lunch
A
seed: ovule after fertilization
plant: embryonic sporophyte
box: seed coat / ovule integuments
lunch: endosperm
41
Q
three generations within one seed
A
- Protective seed coat, formed tissues surrounding megasporangium (sporophyte)
- Embryo, develops from the zygote and is the next sporophyte generation
- Haploid female gametophyte, provides nutrients for the embryo
42
Q
gymnosperm ovule diagram
A
look in notes (lecture 15 slide 25)
43
Q
seed diversity
A
- Size of seeds vary greatly
- Often small seeds allow wider dispersal and remain dormant for long periods
- Dormancy – seed accepts pollen but delays germination until conditions are favourable
44
Q
pollen
A
- Pollen grains are the immature male gametophyte of seed plants
- Pollen grains are the products of meiosis, spore wall formation and gametophyte development; pollen grains have 2-4 nuclei at the time of release
- POLLINATION = transfer of pollen from the pollen sacs (= microsporangia) to the micropyle (opening in ovule integument) of the ovule (gymnosperms) or to the stigma of the ovary (flowering plants)
45
Q
pollen cones and stamens
A
- Pollen sacs (microsporangia) are borne on pollen cone scales of pollen cones in gymnosperms
- In flowering plants, they are called anther sacs and are borne on stalks called filaments; together these form stamens
46
Q
pollen dispersal
A
-wind
-animals
-insects
47
Q
seed ferns
A
- Seed ferns were the first kind of seed plants; the oldest occur in the upper Devonian
- Seed ferns were common in the Carboniferous Period and gave rise to the Cycadophyta, Coniferophyta and Ginkgophyta by beginning of the Permian Period in the late Paleozoic Era
- Seed ferns were also common in the early and mid Mesozoic Era
- They probably gave rise to the Flowering plants (Angiosperms) in the late Jurassic or early in the Cretaceous Period (120-130 mybp)
48
Q
cycads
A
- Cyads are a small group of cone bearing gymno- sperms with distinctive habit, stem anatomy and reproductive structures
- Cycads usually have thick palm tree like trunks
- Leaves are large and compound; leaf vasculature begins from multiple points around the stele and girdle the stem before entering the leaf stalk
-relics of the past
49
Q
ginko
A
- The Ginkgopsida includes just one extant species Gingko biloba possibly no longer existing in the wild
- It is reported to occur naturally in remote mt valleys in Zhejiang province in the Tianmu Shan Reserve
- Ginkgos are dioecious; plants produce either only pollen cones or paired naked ovules on stalks
- Ginkgos have a fossil record going back to the Paleozoic; they were once much more common and grew in Canada
