1. Flowering Plant Life Cycle
Figure 1 Comparing plant life cycles.
Comparing plant life cycles. Plant life cycles, including the angiosperms, exhibit an alternation of generations. Angiosperms are unlike other plant groups, such as the mosses (upper drawing) becuase the gametophyte generation is completely dependent on the sporophyte generation (lower drawing). Also, the gametophyte generation of Angiosperms is usually microscopic.
Principles of Biology

2. Flowering Plant Life Cycle
Figure 2 Seeds can take different forms, but have common structures.
Seeds can take different forms, but have common structures. In some seeds, the food source or endosperm is totally absorbed by the seed leaves, or cotyledons. Other seeds have both endosperm and cotyledons.
Principles of Biology

3. Flowering Plant Life Cycle
Figure 3 Flower structure.
Flowers have many unique reproductive structures including the carpel, stamen, petal, and sepal.
Principles of Biology

4. Flowering Plant Life Cycle
Figure 4 Flower structure identification.
Using Figure 3, what reproductive structures can you identify in this picture of the Blackberry Lily flower (Belamcanda chinensi)?
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5. Flowering Plant Life Cycle
Figure 6 Pollinators range from ordinary to exotic.
Bees typically pollinate a wide variety of flowers and receive nectar or pollen in return (Panel A: left, a bee alighted on an apple blossom. Panel A, right, a bee alighted on the central composite flowers of an Echinacea blossom). In contrast, the Ecuadorian nectar bat (Panel B) only pollinates one type of flower. It has evolved such a long tongue that it can reach twice as far as other related bats (a, retrieving nectar from a test tube). For efficiency, this bat stores nectar in its rib cage in a specialized structure called a glossal tube (c).
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6. Flowering Plant Life Cycle
Figure 7 Double fertilization follows pollination.
Angiosperms undergo double fertilization. Following successful pollination, the pollen grain completes development by growing a pollen tube through the s t y l e, and via mitosis, producing two male gametes (sperm). One fertilizes the egg cell to form a diplod zygote, and one the polar nuclei (producing the triploid endosperm); both essential components of an angiosperm seed.
Principles of Biology