Chapter 23 Seed Plants II: Angiosperms (Basal angiosperms :black_flag:…
Chapter 23 Seed Plants II: Angiosperms
often called Angiospermophyta
the edges of sporophyll primordia crowd against each other and grow shut.
develop into fruit that encloses the embryos as they develop into seeds.
second sperm cell of pollen tube fuses with the polar nuclei of the
Changing concepts about early angiosperms.
carpels occur in superior positions
fossils plant knowledge has become more complete
C.E. Bessery developed the hypothesis of the ranalean flower.
developed hypothesis of Ranalean flower
speaks of generalized flowers
contain the living descendants of groups of angiosperms
their ancestors became reproductively isolated.
Classification of Flowering Plants
uses arrangement of structures, veins, and other characteristics
large group with many families, genera, and species
angiosperms are classified
three sepals, three petals, three stamens, and three carpels.
more diverse and include greater number of families , genera and spoecies.
Leaves usually have parallel veins because the leaves are elongate and sharp shaped.
have become highly modified
contains many aquatic herbs
most often found in swamps and marshes
do not waste carbon energydo not waste carbon energy
many previous families grouped in Asparagales
contains many ornamental plants
species have fused carpels
large clade with many families
gives a sense of evolution and diversification
Orchiaceae is the largest/most diverse family
only one family
about 3,500 species, contains the palms
contains grass families
has about 8,000 species
contains familiar house plants
unique nature of sieve tube plastids
share many derived characters
consist of several small and two large groups
two large clades
createst number of species
very few stamens
contains many well-known plants
very potent chemicals
Division Pteridospermophyta: Seed Ferns
ring of vascular bundles surrounding pith
any woody plant with fern-like foliage
thought to have evolved from the Anueophytales
wood was manoxylic
leaves similar to true ferns
foliage leaves bore seeds
(unlike seed ferns)
(unlike seed ferns)
thick cortex around stem
Division Cycadophyta: Cycad
trunk is covered with bark
produce seed and pollen cones
short (less than 1-2 cm tall)
cycad foilage leaves do not bear ovules.
much larger group with more species.
Highly prized ornamental in the warmest parts of the united states.
Division Progymnospermophyta: Progymnosperms
A third group to evolve from trimerophytes
primary xylem in stems was a protostele
vary in stature
all had a vascular cambium and secondary growth
contains the more relictual progymnosperms
trunks upto 1.5m in diameter and 12 m tall.
abundant wood with secondary phloem
more derived progymnosperm
"fronds" were planted branch systems
ring of primary xylem bundles
leaflets were serially arranged simple leaves
Evolution of seeds.
four types of pollen became common common after Upper Devonian Period
earliest known species
from Middle Devonian Period
some fossils help us understand the early stages
hole in integument
permitted sperm cells to swim to the egg
holding area for microspores
evolved into pollen grains
evolved into ovules with integuments
plant that give rise to monophyletic group of woody plants
seeds originated establishing seed plants.
plants with naked ovules.
example; pine cones.
Division Cycadeoiphyta: Cycadeoids
both cycadeoids and cycads
each ovule had a stalk
had vegetative features
contained microsporophylls and megasporophylls
megasporangium was surrounded by an integument
was cup shaped
contained numerous sporangia
Division Coniferophyta: Conifers
simple venation of leaves
two types of shoot
leaf veins contain
never herbs, vines, or annuals
microscopic axillary bud
its megasporophylls are fused to form ovuliferous scale
moderate to gigantic size
Division Ginkophyta: Maidenhair Tree
contains a single living species
looks much like a large dicot tree
lacks vessels and axial parenchyma
reproduction is dioecious
wood like conifers
contains three groups of enigmatic plants
about 40 species
touch shrubs and brushes
leaves similar to those of dicots
mostly vines or small shrubs
short, wide stem
exists only in deserts of South Africa or in cultivation
only species in the genus
only two leaves