Lecture 3 Flashcards
what were some characteristics of early land plants
- remaining close to the substratum
- crowding of semi-aquatic habitats
- soil formation
what did the early land plants need to have (evolve) protection from
- airy (dry) conditions
- UV radiation (photo-bleaching of pigments)
how did early land plants change to evolve to conditions
- need for water (reproductive strategy changes)
- need for dormancy (propagules)
- protected cells (embryo-bytes)
- lignified walls for strength so they could grow upright
what evolved as a result of plants coming out of water and onto land
lignified walls, roots, vasculature, stems/branching, leaves, flowers, fruits, seeds
what did the rhyniophytes branch off to give rise to
lycophytes
what are rhyniophytes
early vascular plants (ex. cooksonia caledonica)
what type of branching did the rhyniophytes (early vascular plants) have
dichotomous branching
what are the three types of branching
dichotomous, pseudomonopodial, monopodial
what is protostele vs siphonostele
protostele has no pith and siphonostele has pith in the centre
what is sporogenous tissue
spore generating tissue
what is homosporous tissue
when the tissue gives rise to spores that all look and behave the same
what is heterosporous tissue
when meiosis results in spores of two sizes and sexes
what are the distinguishing features of lycophytes
- lateral sporangia
- exarch protostele
- microphylls
- heterosporous
- presented by only 5 genera
what are microphylls
like leaves, flaps of photosynthetic tissue with only one vein
- thin vasculature
what are megaphylls
flaps of photosynthetic tissue with branching veins
- increasingly vascularized
what is lateral sporangia
when the sporangia or spore producing structures are located on the sides of a stem
what to micro and megaspores lead to
micro and megagametophytes
what is an exarch protostele
metaxylem on the outside and protaoxylem on the inside layers
what are lycopodium
genera of lycophytes
- genus of clubmosses
- isosporus
- spores clustered into club shaped strobili
- gametophytes are subterranean and associate with mycorrhizae
what are microsporophylls vs megasporophylls
microsporophylls are male and megasporophylls are female sporangia
what are equisetum
- horsetails
what do ferns have
- rhizomes
- green fronds
- spores clustered in sori
- prothalli as gametophyte
- asexual reproduction
what is a prothallus and how is it made
the gametophyte, created from spores that fall onto the ground
what is the indusium
umbrella like covering over the sorus
what are sori
clusters of spores, position and location of sori is used to distinguish between ferns
what is the megasporangium of the ovule
2n, gives rise to and contains the egg
what is the functional megaspore of the ovule
haploid n, the egg
what is the integument ovule
the covering over the ovule, hard covering
what is a seed
unit of perennation and dispersal in spermatophytes formed by ovule maturation after fertilization
what is a spermatophyte
a seed producing plant
are spermatophytes homosporous or heterosporous
heterosporous
what is pollen
microspore containing a microgametophyte (male) that is transferred passively to the megagametophyte via pollination
what is the ovule
structure that combines integuments, megagametophyte and nucellus
what is the carpel
consists of the stigma, style, ovary
- develops into ovules which develop into seeds after fertilization
- the rest of the carpel develops into a fruit
describe the gymnosperms
vascular land plants with naked (gymnosperms) seeds, use special reproductive structures called cones, pine leaves
what is a cone
modified branch with woody, scale like leaves (sporophylls)
what are sporophylls
woody scale like leaves on male pinecones
what are ovuliferous scales
on female pinecones
describe ovuliferous scales
have two exposed/naked ovules on the upper surface and a subtending sterile bract
describe the inside of the male cone
microangiospores have microspore mother cells that produce 4 haploid spores after meiosis
how do microspores develop in male cones
the develop into a winged pollen grain which contains two prothallial cells, a generative cell and a tube cell
when does pollen shedding of gymnosperms occur
in spring (sulphur showers)
what is a spermatogenous cell
a sperm body cell
are gymnosperms gametophyte or sporophyte dominant
sporophyte
how are the ovules placed in gymnosperms
- they are exposed and the pollen grains reach the egg passively
- embryo develops relatively sheltered but is easily dislodged by animals
are angiosperms sporophyte or gametophyte dominant
sporophyte
do flowers have sterile or fertile components or both
both
how is the sperm cell delivered to the egg cell
via pollen tube formation
what do carpels contain and what do they do
stigma, style and ovule
- stigma and style develop into the fruit
- ovule develops into seeds
what is the name for “closed flowers” (ones that are self pollinating
cleistogamous
what is the name for cross pollinating plants
chasmogamous
what does anemophilous describe
cross pollination by wind
what does entomophilous describe
cross pollination by insects (ex bees)
what does zoophilious describe
cross pollination by vertebrates (ex birds)
what is the visual difference between cleistogamous and chasmogamous flowers
cleistogamous flowers do not involve pollinating agents or have nectar and elaborate showy petals
what are phyllomes
vegetative leaves
what does it mean that a structure is a determinate structure
it is a final structure
what is unique about nymphaea (water lily)
there is a gradual transformation of petals to stamens, and filaments of outer stamens actually appear petalloid
distinguish between gynoecium and androecium
gynoecium is the female reproductive parts of flowers, androecium is the male parts
what is corolla plural for
petals of a flower
what is the calyx
plural for the sepals of a flower
what is a perianth
the corolla (petals) and calyx (sepals) collectively
what is a tepal
when perianth (corolla/petals and calyx/sepals are not distinguishable
what is the difference between actinomorphic and zygomorphic flower symmetry
actinomorphic means it exhibits radial symmetry and zygomorphic means it exhibits bilateral symmetry (only divides equally into one plane)
what is special about scaevola taccada
the flowers look like only half a flower (like half the petals are picked off) which means it exhibits unique symmetry
