exam 4: seedless vascular plants- plants and people
family Salviniaceae
-2 genera: Salvinia and Azolla -floating ferns -sporangia in sporocarps -Azolla with tiny crowded bilobed leaves on slender stems -with colonies of a cyanobacterium -Salvinia has larger undivided leaves in whorls of 3
class psilotopsida
-2 orders: Ophioglossales and Psilotales -homosporous -a single leaf is produced each year
fertilization of pines
-4 tiers of cells are produced -the tier farthest from the micropyle forms an embryo and the other cells become suspensor cells -the integument develops into a seed coat
seed
-a case of heterospory that has been modified to form a ovule -a mature ovule containing an embryo
leptosporangium
-advanced -arise from one single superficial cell which divides transversely -inner cell will contribute to the sporangial stalk or remain inactive -outer cell will give rise to a complex stalked sporangium with a globose capsule with a one cell thick wall -below the thick wall is a tapetum (provides nutrients) -the inner mass develops into spore mother cells -most are homosporous
Class Marattiopsida
-ancient -living ones are tropical -6 living genera
progymnosperm
-appeared during the late paleozoic -intermediate between trimerophytes and seed plants -dispersed spores and secondary xylem -bifacial vascular cambium: producing secondary xylem and phloem -have spores not seeds
lycopodiales/lycopodiaceae
-club mosses -genus Lycopodium -sporophyte is a branching rhizome with aerial branches and roots -roots and stems are protostele -microphylls are spirally arranges -homosporic -sporangia single on fertile microphylls called sporophylls which are interspersed with vegetative microphylls or grouped into terminal strobili or comes -gametphytes are bisexual and mycorrhizal -archegonia and antheridia take years to form -biflagellated sperm requires water for fertilization -embryo grows in venter of archegonium -sporophyte remains attached to gametophyte
pines
-conifers with unique leaf arrangements -genus Pinus -first leaves are needlelike and arranged spirally -after a year the leaves are produces in bundles or fascicles -fascicles are short shoots wrapped by small scalelike leaves -a short shoot is a determinate branch, sometimes may produce indeterminate growth -leaves are adapted to grow in xeric conditions
seed scale complex
-consist of the olviferous scales (2 ovules) and a sterile bract -each ovule consists of a megasporangium surrounded by an integument -each megasporangium contains a single megasporocyte that gives rise 2 4 megaspores, only one of which is functional
early vascular plants
-extinct -includes phyla Rhyniophyta, Zosterophyllophyta, nd Trimerophytophyta
phylum monilophyta
-ferns and horsetails -ferns are herbaceous: no secondary growth -4 major lineages
Tmesipteris
-found in australia and new zealand -grows as a epiphyte on tree ferns and other plants -leaves are larger with a single unbranched vein
isoetales/isoetaceae
-genus Isoetes -quill worts -aquatic -sporophyte consists of a corm with quill-like microphylls on upper surface and roots on lower surface -heterosporous -outer megasporophylls and inner microsporophylls -ligule is present -cambium adds secondary tissue to the corm
sellaginellales/selaginellaceaee
-genus Selaginella -spike mosses -mostly tropical in moist places -sporophyte is herbaceous with microphylls -sporophylls in strobili (cone) -ligule -stem and room are protostele -heterosporous with unisexual gametophytes -microgametophytes are endosporic and consist of 1 prothalial cell and the antheridium -megagametophytes are endosporic -sperm are biflagellated -embryo develop in a suspensoe
family Marsileaceae
-grows on damp or wet soil or with the leaves -leaves resemble a four leaf clover -sporocarps are reproductive structures resistant to drought that contain the sori with megasporangia and microsporangia
genus Equisetum
-homosporous -sporangia borne in groups on sporangiophores which are clustered in a strobilus on the apex of aerial stems -spores are provided with elaters, thickened bands from the outer spore wall that help with dispersal -gametophytes are green and free living -usually bisexual -sperm is multiflagellated and requires water
class Equisetopsida
-horsetails -have joined stems -eusporangiate -1 genus: Equisetum -common on moist or damp places on streams or edge of woods -leaves are small and scale like forming whorls around the stem at the nodes -internodes are ribbed with silica deposits -aerial stems arise from underground rhizomes
how does an ovule become a seed
-in modern seed plants the ovule consists of a nuclellus enveloped by one or 2 integuments with a micryple -the nuclellus contains a megagametophyte composed of nutritive tissue and archegonia -after fertilization, the integuments become the seed coat and the seed is formed
phylum coniferophyta
-includes pines, firs, and spruces
megaphylls
-larger, usually associated with siphonoseles and eusteles, with leaf gaps and a branching vein system -evolved by fusion of branch systems
pollination
-occurs in the spring -pollination drops exuded from the micropyle trap pollen grains and carry then to the nucellus -the scales grow together and protect the ovules -pollen grain germinates and forms a pollen tube
megasporangiate cones
-ovulate cones -found on upper branches -larger and complex -the cone scales are modified determinate branch systems known as seed-scale complexes
microsporangirate cones
-pollen producing -found on the lower branches and are small -microsporophylls are spirally arranged, each with 2 microsporangia -a microsporangia contains many microsporocytes that produce haploid microspores that develop into pollen grains
eusporangium
-primitive -parent cells are located at the surface of the tissue and divide periclinally -the outer cell layer will form the wall of the sporangium -the inner layer will form the spore mother cells
microphylls
-small leaves with only one single strand of vascular tissue (no gaps) usually associated with protosteles -evolved as outgrowths or enations
phylum lycopodiophyta
-the lycophytes -2 lineages diverged in devonian period: lycophyte clade and euphyllophyta clade -herbaceous with microphylls -3 orders with 1 family each
pollen tube in cycads and ginkgo
-the microgametophytes produce pollen tubes that grow in the tissue of the nuclellus absorbing nutrients -eventually the pollen tube bursts over the archegonium releasing the multiflagellated swimming sperm cells
as plant life progressed on land ___
-the plant body developed roots, stems, and leaves -the gametophytic generation underwent a progressive reduction in size and became nutritionally dependent upon the sporophyte -seed evolved
Class Polypodiopsida
-water ferns -most familiar ferns -rhizomes are siphonostele -leaves/fronds are megaphylls -lamina an be simple or divided into leaflets or pinnae attached to the rachis -sporangia occur in clusters (sori) -circinate venation -have indusia -bisexual gametophytes -water required for fertilization -embryo receives nutrients from gametophyte through a foot -sporophyte is perennial while gametophyte is short lived
Psilotum
-whisk germ -tropical and resemble rhyniophytes -sporophyte is dichotomously branched with scale like structures -gametophytes are bisexual, rhizome like, and mycorrhizal -sperm is multiflagellated and requires water for fertilization -sporophytes are initially attached with a foot to the gametophyte
order and families of Class polyposiopsida
1 order: Salviniales 2 families: Marsileaceae and Salviniaceae
4 major lineages (classes) of phylum monilophyta
1. Psilotopsida 2. Marattiopsida 3. Polyposiopsida 4. Equisetopsida
5 phyla of living seed plants
1. cycadpphyta 2. ginkgophyta 3. coniferophyta 4. gnetophyta 5. anthophyta
3 orders/families of lycophytes
1. lycopodiales/lycopodiaceae 2. selaginellales/selaginellaceae 3. isoetales/isoetaceae
events leading to the evolution of an ovule
1. retention of the megaspores within the megasporangium which is fleshy and called the nucellus 2. reduction of the number of megaspores mother cells in each megasporangium to one 3. survival of only one of the four megaspores 4. formation of a megagametophyte inside the single functional megaspore (endosporic) 5. development of the embryo within the gametophyte 6. formation of an integument that completely envelopes the megasporangium, except for an opening or micropyle 7. modification of the apex of the megasporangium to receive microspores or pollen grains
leaf of Psilotopsida
2 parts: a vegetative portion or blade and a fertile segment
4 cells in each pollen grain
2 prothallial cells, 1 generative cell, and 1 tube cell
order ophioglossales
4 genera but only Botrychium (grape ferns) and Ophioglossum (adder's tongues) are found in UA
origin of embryophytes
Chara- or Coleochaete-like green algae
phyla of ferns and fern allies
Lycopodiophyte and Pteridophyta
genera of order psilotales
Psilotum and Tmesipteris
siphonostele
a central pith surrounded by vascular tissues, the phloem may be outside or on both sides of the xylem; with leaf traces and leaf gaps
life cycle of embryophytes
alternation of heteromorphic generations
a seed consists of ___
an embryo, stored food, and a seed coat
when were flowering plants dominant
appeared 125 mya and dominant ever since
when were seed plants dominant
arose at the end of devonian (380 mya). gymnosperms dominated from the mesozoic to about 100 mya
microsporangia and megasporangia in pines
borne in separate cones or strobili on the same tree
when were monilophytes, lycophytes, and proymnosperms dominant
complex group, dominant from devonian to carboniferous (375-290 mya)
most numerous, widespread, and ecologically important gymnosperms
coniferophyta
immature ovule
consists of a megasporangium surrounded by one or two additional layers of tissue, the integuments
zosterophyllophyta
dichotomously branched, stem only, homosporous and heterosporous, protostele, lateral sporangia. related to lycophytes
rhyniophyta
dichotomously branched, stems only, with terminal sporangia, homorsporous, protostele, ancestors of trimerophytes
2 kinds of sporangia in ferns
eusporangium and leptosporangium
____ resolved the problem of water and food transport
evolution of xylem and phloem
seedless vascular plants
ferns and fern allies
vascular plants
ferns, gymnosperms, angiosperms
haploid gametophytic generation in the seed
food reserve
megaspore
forms female gametophyte (megagametophyte)
microspore
forms male gametophyte (microgametophyte)
bryophyte gametophyte vs sporophyte
gametophyte is larger and free-living, sporophyte permanently attached to and nutritionally dependent from the gametophyte
all seed plants are ____
heterosporous
most vascular plants are (homosporous/heterosporous)
heterosporous
euphyllophyta clade
includes all other living vascular plant lineages (ferns, fern allies, and seed plants)
lycophyte clade
includes the modern lycophyte lineage
what happens to the generative cell after pollination
is forms 2 cells: a sterile cell and a spermatogenous cell. the spermatogenous cell will divide, forming 2 sperm
trimerophytophyta
larger, complex branching, only stems, homosporous, protostele, terminal sporangia. ancestors of ferns and progymnosperms
polyembryony
megagametophytes produce several archegonia thus several embryos may develop within a single ovule
megasporangia are borne on ____
megasporophylls
2 types of leaves
microphylls and megaphylls
microsporangia are borne on ____
microsporophylls
bryophytes
mosses, liverworts, hornworts
gymnosperm means
naked seed
is water required for fertilization with gymnosperms
no
do all ferns have sporophytes
no, in some ferns the gametophytes reproduce asexually by gemmae and sporophytes are never formed
in gymnosperms, the microgametophytes develop as ____
pollen grains
protostele
primitive, no pith, usually the phloem surrounds the xylem
heterosporous plant
produce 2 types of spores: microspores and megaspores with endosporic development
homosporous plant
produce only one kind of spore, which will form a bisexual gametophyte with exosporic development (outside the spore wall)
seed coat
protects the embryo and the food storage, critical for germination and establishment of the new plant on an inhospitable land
vascular cylinders or stele classification
protostele, siphonostele, or eustele
classes ____ and ____ are eusporangiate ferms
psilotopsida and marattiopsida
tallest vascular plant
redwood Sequoia sempervirens from CA (a conifer)
ligule
scarelike outgrowth near the base of the upper surface of the microphyll and sporophyll
suspensor
serves to thrust the developing embryo deep within the nutrient rich tissue of the female gametophyte
when were early vascular plants dominant
small size and simple morphologies, dominant during the Silurian to Devonian (425-370 mya). 3 phyla: rhynophytes, zosterophyllophytes, and trimerophytes
over evolutionary time, the gametophytes of vascular plants have become ___
smaller and simpler
indusia
specialized outgrowths of the leaf covering the sori
vascular plant gametophyte vs. sporophyte
sporophytes are larger than gametophytes and free living
what happens 15 months after pollination
the archegonia are formed and the pollen tube reaches the egg cell (fertilization)
embryophytes
the bryophytes and vascular plants, both of which produce embryos; a synonym for plants
what happens after pollenation
the endosporic microgametophyte produces a tubular outgrowth, the pollen tube
what happens 6 months after pollination
the megaspore starts forming the megagametophyte
lycophytes are characterized by____
the presence of microphylls
diploid sporophytic generations in the seed
the seed coat and embryo
pollen tube in conifers and gnetophytes
the sperm are nonmotile and the pollen tubes convey the sperm directly to the archegonia
how are pine leaves adapted to grow in xeric conditions
thick cuticle, thick hypodermis stomata sunk, mesophyll with wall ridges projected into the cells, resin ducts, 1-2 vascular bundles surrounded with transfusion tissue, endodermis
how is the gymnosperm pollen grain transferred
wind (pollination)
eustele
with a vascular cylinder consisting of a system of discrete strands around a pith
circinate venation
young leaves are coiled or circinate