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Ch. 23 Seed plants II: Angiosperms (Classification of flowering plants…
Ch. 23 Seed plants II: Angiosperms
Changing concepts about early angiosperms
Hypothesis of the ranalean flower
C.E. Bessey
Around 100 years ago
A
Magnolia
type flower thought to be relictual, or generalized
it has all parts
sepal
petal
stamens
Arranged spirally
carpels
Transition from gymnosperm to angiosperm
believed to have occurred during the Mesozoic era
approximately 130 million years ago
Angiosperms contain the largest number of living species
Division Magnoliophyta
257,000 species
Angiosperm Carpels
Edges of sporophyte primordia grow shut
Closed carpel
closes so completely that no sign of a seam remains
Develops a fruit that encloses the embryos as they develop into seeds
Double fertilization
Second per of the pollen produces the endosperm nucleus
Vesselless plants
have wood without vessels
Two types
Primary
Vesselless because their ancestors were
Secondary
Lost vessels on their own
Features
Pistils
fusion of carpels into a single structure
Sympetally
Fusion of petals into one structure
Floral zygomorphy
flowers that are bilaterally symmetrical
Classification of flowering plants
Monocots
Have only one cotyledon on each embryo
Their leaves typically have parallel veins
vascular bundles are distributed throughout the stem
Never have ordinary secondary growth and wood
Flower parts arranged in multiples of three
Eudicots
reticulate venation in the leaves
Have two cotyledons for each embryo
vascular bundles occur in only one ring on the stem
may be woody, herbaceous, or succulent
Flower parts occur mostly in sets of 5
Basal angiosperms
reproductively separate from the other angiosperms
Basal Angiosperms
Ancestors became reproductively isolated from the other groups
Water Lillies
Pollinated by animals
Uniaperturate
Pollen grains have only a single germination pore
Monocots
Lack ordinary secondary growth and wood
Perianth
three outer members
Three inner members
Called tepals
typically remain free, don't fuse
Alismatales
aquatic herbs and aquarium plants
found in swamps and marshes
partly or entirely submerged
no transpiration
Do not produce fibers
air bubbles
Make the plant buoyant
Liliales
Spots or lines on the petal
1300 species
Asparagales
Septa
fused carpels
Open to secrete nectar
septal nectaries
Morphologically diverse
Commelinoid Monocots
have unique types of epicuticular wax
Arecales
The palms
Solitary trunk
Scattered vascular bundles
Leaves occur only near the shoot apex
Poales
Includes wheat, corn, rye
Wind pollinated
Sepals and petals of little importance
Carpals are fused together
Zingiberales
Large, showy flowers
Adjacent sepals
fused to each other to form a tube
Bilaterally symmetrical
Petals fused
Three carpels
Fused
Eudicots
Tricopolate
have three germination pores
Basal Eudicots
Caryophyllales
Produce betalains
water-soluble pigments
Perisperm
nucellus cells proliferate to form nutritive tissue
Santales
highly modified, mostly parasitic plants
may be holoparasitic
have no chlorophyll at all
Rosid clade
Fabids
Malvids
pinnately compound leaves
e.g. roses
Asterid Clade
e.g. sunflower
no betalains
iridoid compounds
produce chemicals to deter or kill animals
two groups of orders
lamiids
campanulids
