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Seed plants II: Angiosperms, Commelinoid monocots, Calla_palustris1,…
Seed plants II: Angiosperms
Changing concepts about early angiosperms
Concepts about the nature of early angiosperms have changed as out knowledge of existing and fossils plants has become more complete
transition from gymnosperms to angiosperms
double fertilization - developmental plasticity didn't evolve more then once
the early angiosperm used to be large bush or small tree while the present angiosperm are large trees, herbs, bulbs, vines
there used to be complete flowers in the early angiosperm while the present angiosperm have incomplete or imperfect flowers.
early angiosperm used to have evergreen leaf retention while the present angiosperm are deciduous or leafless
Classification of flowering plants
In the early 1980s the most widely used monograph of the division was an integrated system of classification of flowering plants.
The system became inconsistent over time once we learned more about the plants so now currently the two widely used books are plant systematics, a phylogenetic approach and plant systematics by Michael Simpson
Flowering plants began to follow two distinct lines of evolution and are almost all angiosperms are classified as monocots or eudicots
chloranthaceae
Amborella
Nymphaeales (water lilies)
Eudicots
Austrobaileyales
ceratophyllum
monocots
Basal angiosperms
3 groups - Amborellaceae, Nymphaeaceae, + Austrobaileyales
originated while angiosperms were still young clade
their ancestors became reproductively isolated from the other early flowering plants before distinctive angiosperm traits had originated
they contain the living descendants of several groups that originated while angiosperms were still a young clade
Monocots
Asparagales
most form nectaries in a usual way but their carpels fuse side by side. the fused sides is called the septa.
dioacoreales
it has familiar and important food crop like yam
they have petiolate, broad leaves with reticulate venation
Liliales
most important feature is they have spot or lines on the petals and of rather ordinary nectaries formed at the base of the tepals.
it is defined as the petaloid monocots with large colorful flowers.
Aracales
they have scattered vascular bundles like that of most monocots
all species have simple leaves that are fully expanded y have either pinnate pattern or palmate one
Alismatales
plants tend to be thin and delicate, having very little sclerenchyma and almost no xylem.
plants are highly modified often having large leaves and considerable amount of fibers and thick cuticle on the leaf epidermis.
zingibirales
its largest family zingiberaceae has around 1000 species
it contains some of the most familiar house plants like marantha, canathea, gingers, banana etc.
Poales
they include grass as well as wheat, barley, oats, corn, sugarcane etc. bamboo also comes under this group
Eudicots
Basal eudicots
they produce a group of water soluble pigments called the betalains
phloem plastids contains deposits of fibrous protein located as a ring just interior to the plastid membrane
their ancestral group lacked petals in their flowers.
Rosid clade
this clade has plants which are diverse in many ways but they still have some common characters that put them under the same family
the large clades of rosids are: fabids and malvids. they together have more than 100 families.
Asterid clade
it is the most derived large clade of eudicots which contains plants such as sunflower, periwinkle,petunia and morning glory
they always have few number of stames( no more than the number of petals in that flower.)
it may have originated around 60 million years ago
Commelinoid monocots
