Lecture 3

• Anthophyta appeared about 150 million years ago then exploded into many species
• The most recent common ancestor of all living angiosperms arose about 150 million years ago
• 105 million years ago, less than 20% of plant species were angiosperms
• 65 million years ago, more than 80% of plant species were angiosperms
• The explosion in angiosperm and other species is called the Angiosperm Terrestrial Revolution
• The diversification of the angiosperms coincided with a dramatic diversification of other organisms
• The hypothesis is that the rise in angiosperm species fueled the diversification of other groups
• Today, 85% of plant, animal and fungal species live on land rather than in the sea
• Half of the land plant, animal and fungi species live in tropical rainforests
• An explosive burst in terrestrial diversity occurred from 100 to 50 million years ago
• During the Angiosperm Terrestrial Evolution the biosphere expanded to a new level of productivity
• The boost of terrestrial diversity coincided with innovations in flowering plant biology and evolutionary ecology
• Flowering plants had innovations to their flowers and efficiencies in reproduction, coevolution with animals, especially pollinators and herbivores, photosynthetic capabilities, and adaptability and ability to modify habitats
• The rise of angiosperms triggered a macroecological revolution on land and drover modern biodiversity to new high levels, a series of processes called the Angiosperm Terrestrial Revolution
• Angiosperm diversity and species number comes from insect pollination, flexibility in seed production and dispersal, greater genetic and phenotypic flexibility in cell and shoot elongation, more complex mechanisms for activating and repressing the genes, and greater complexity of the flower
• There are 300,000 named flowering plant species and an estimated 400,000 species total
• Flowering plants have reproductive organs in their flowers
• Flowering plants are sporophyte dominant
• Flowering plants are heterosporous, they only produce one size of spore
• Flowering plants have pollen as the microgametophyte
• The megagametophyte in flowering plants has 8 nuclei
• Flowering plants have a triploid endosperm
• Flowers have 4 whorls of modified leaves
• There are 2 main groups of Anthophyta
• Anthophyta split into monocots and eudicots about 125 million years ago
• Monocots include grasses, orchids, irises, lilies and palms
• Monocots have one cotyledon
• The leaves of monocots usually have parallel veins
• The stems of monocots have vascular tissue that is scattered
• The roots of monocots are usually fibrous and do not have a main root
• Monocots have pollen grains with one opening
• The floral organs of monocots are usually in multiples of three
• Eudicots include oaks, maples, dandelions, sunflowers, legumes, melons, potato, poppies, and roses
• Eudicots have two cotyledons
• The leaves of eudicots usually have netlike veins
• The stems of eudicots usually have vascular tissue arranged in a ring
• The roots of eudicots usually have a taproot present
• Eudicots have pollen grains with three openings
• The floral organs of eudicots are usually in multiples of four or five
• 85% of angiosperm species have hermaphroditic flowers