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Seed plants II: Angiosperms (Monocots # (Liliales (dna evidence (smaller…
Seed plants II: Angiosperms
Changing concepts about early Angiosperms
concepts have changed as knowledge has grown
hypothesis of ranalean flower
developed by C.E. Bessey
a magnolia thought to be relictual
such a flower is generalized
it has all parts
carpals are arranged in a superior position
monocot flowers have three stamens and three carpels
#
eudicot flowers have four or five of each
#
all parts are arranged spirally
long ago botanists' concluded that angiosperms are monophyletic
complex features probably did not evolve more than once
recent DNA studies indicate monophyly of angiosperms
transition from gymnosperm to angiosperm
Jurassic and Lower Cretaceous periods
earliest leaf fossils from lower Cretaceous period
130 million years ago
130 million years ago
oldest wood from an angiosperm
from apian epoch
125 million years ago
Flowers and fruits
lower cretaceous people
Classification of Flowering Plants
magnoliaphyta
large group with many families, genera, species
hard for an individual taxonomist to study all
soon after origin, flowers took two paths
monocots
generally
have one cotyledon on each embyo
leaves have parallel veins
vascular bundles distributed in the stem
never have ordinary secondary growth and wood
flowers
parts arranged in multiples of three
three sepals
three petals
three stamens
three carpels
eudicots
#
classify almost all angiosperms
generally
two cotyledons and reticulate venation in the leaf
vascular bundles one ring in the stem
flowers
sets of five (SOMETIMES FOUR)
rarely three
can be woody, succulent, or herbaceous
Basal Angiosperms
ancestors
reproductive isolated from other early flowering plants
three groups arose from this clade
amborellaceae
one species, Amborella trichopoda
wood contains only tracheids
small trees in new Caledonia
nymphaeaceae
water lillies
small, soft bodied herbs
Austrobaileyales
Monocots
#
arose from early angiosperm 80-100 million, maybe 120 million years ago
all lack ordinary secondary growth and wood
ancestors probably herbs with little to no vascular cambium
perianth consists of three outer/inner membranes
#
one theory is that ancestors had broad leaves and were aquatic
alismatales
many aquatic herbs and aquarium plants
most often found in swamps and marshes
partly or entirely submerged
air chambers make the plant bouyant
plants do not waste carbon energy by producing fibers
tend to be thin and delicate
sclerenchyma and almost no xylem
flowers are large and showy
Liliales
a large group with many highly derived families
dna evidence
smaller clade, 11 families and 1300 species
easy to assume they are dicots at first glance
Asparagales
large clade
gives us a sense of evolution and diversification
several morphologic and DNA synapomorphies that unite this group
carpels fuse side by side starting at the base
open areas secrete nectar
Dioscoreales
small order has only one family
familiar food crop
Yams
starchy tubers
petiolate, broad leaves with reticulate venation
Commeliniod Monocots
Eudicots
Much larger group than monocots
divided into numerous clades
more difficult to characterize than monocots
flower parts arranged in whorls not spirals
lamens have well-defined filament
Basal Eudicots
Ranunculaceae
flowers have little fusion of parts
clades that diverged in early eudicot evolution
each flower usually has stamens and carpels
papaveraceae
poppy family
know for numerous ornamental species
Argemone
Eschscholzia
Papaver
papaver somniferum
opium poppy
source of milky latex
haversted for opium
how we get the pain killer morphine
Caryophyllales
cacti (crustaceae)
iceplant (aizoaceae)
Portulaca (portulaceae)
bougainvillea and four o'clocks (Nyctaginaceae)
spinach beets and russian thistle (Amaranthaceae)
Carnations and Chickweed (Caryphyllales)
Qualities
Produce water soluble pigments called betalains
ancestral group probably lacked petals
endosperms develops only a little
nucleus cells proliferate
forms nutritive tissue called perisperm
perisperm usually absorbed by the time the seed is mature
most members herbaceous
either no wood or anomalous wood
probably arose from ancestors similiar to Ranunculaceae
suspected to be shrubby or
rosid Clade
Many families
so diverse it is difficult to see how they are related
two large groups and several small ones
named for the roses, however this is not the whole group
also contains grapes (vitales)
marijuana
Asterid Clade
sunflower, periwinkle, petunia, morning glory
originated 60 million years ago
three basic features
petals are fused together in a tube
always have a few stamens
stamens alternate with petals
60,000 species
many are important medically
