Chapter 23: Seed Plants ll: Angiosperms
Concept
Changing Concepts About Early Angiosperms
Classification of Flowering Plants
Basal Angiosperms
Monocots #
Commelinoid Monocots
Eudicots
Basal Eudicots
Rosid Clade
Asterid Clade
magnoliophyta
often called the Angiospermophyta
common to refer to angiosperms as the most advanced group of plants
most derived
occasionally
called the peak of plant evolution
statement should be examined carefully
angiosperm carpels
edges of sporophyll primordia crowd against each other
grow shuts
sometimes leaving a visible suture
sometimes closing completely that no sign of a seam remains
closed carpel
develops into a fruit that encloses the embryos as develop into seeds
double fertilization
universal in flower plants
primitively vesselless
lacked vessels b/c their ancestors lacked
conundrum for many years
quite a few plants were considered to be basal angiosperms on basis woods without vessels
secondarily vesselless
tracheid-based
gymnosperm-like wood
derived feature that looks like a primitive one&misled us for years
other derived features carpels into single structure
pistil
sympetally
zygomorphy
fusion of petals into one structure
flowers bilaterally symmetrical
not radially symmetrical
ranalean flower
approximately 100 years ago
C.E Bessey developed the hypothesis
Magnolia-type flower was relictual
generalized
all parts
sepals
petals #
stamens
carpels
these are arranged spirally
occur in superior position
above the other parts
wind-pollinated trees
alders
elms
oaks
plane trees
grouped together in "subclass Hamamelidae"
considered the most relictual living flower plants
monocots/eudicots #
flower plants began to follow two distinct lines of evolution
currently, almost all angiosperms are classified
basal angiosperms
early angiosperms diverged into several clades
monocot/eudicot divergence did not occur right away
Magnoliophyta
large group with many families
genera
species that is rare for an individual taxonomist to attempt to study
classify the entire group
contain the living descendants of several groups that originated while angiosperms were still a young clade
uniaperturate
pollen grains only have single germination pore
other basal angiosperms&monocots
tepals
three outer&inner members
looks similar that rather than using the terms sepals&petals
perianth members
early monocots diverged into a series of clades whose extant members are classified into approximately ten orders
four orders of monocots
differ from others in several unusual synapomorphies
they have unique types of epicuticular wax
wall have unusual types of hemicelluloses&ultraviolet-flurescent compounds
name for rose order rosales
many families
take as a whole
diverse with respect to vegetative body,flower,chemistry,ecology that is difficult to see they all related
two large clades of rosids
fabids
called eurosids I
malvids
eurosids II
the most derived large clade of eudicots
contain plants such as
sunflower
periwinkle
petunia
morning glory
flower plants were assigned to either Monocots or Dicots
many families did not seem to fit well in either group
anthocyanin pigments
all caryophyllales instead produce a group of water-soluble pigments
perisperm
nucellus cells proliferate
form a nutritive tissue
surrounds the develop embryo