Plant Diversity II: The Evolution of Seed Plants Chapter 30

Learning Targets

Seeds and pollen grains are key adaptations for life on land 30.1

Seeds vs. Spores Spores Seeds No protection or support for embryo Rely on environmental conditions for dispersal Short lifetime (no dormancy) Provide protection and support for embryo Dispersal via various means (fruits  animals) Dormancy allows a waiting period for ideal conditions

Five Derived Traits of Seed Plants Reduced gametophytes Microscopic male and female gametophytes (n) are nourished and protected by the sporophyte (2n) Male gametophyte Female gametophyte Heterospory Microspore (gives rise to a male gametophyte) Megaspore (gives rise to a female gametophyte) Ovules Integument (2n) Megaspore (n) Ovule (gymnosperm) Megasporangium (2n) Figure 30.UN04 Summary figure, Concept 30.1 Pollen Pollen grains make water unnecessary for fertilization Seeds Seeds: survive better than unprotected spores, can be transported long distances Seed coat Food supply Embryo

Gymnosperms bear “naked” seeds, typically on cones 30.2

Gymnosperms Ex: Cycads, Ginkos, Gnetos, Conifers SEED! Inside a seed is the female gametophyte Pollen is male gametophyte If sperm reaches ova, zygote forms Seeds help plants survive harsh conditions Gymnosperms have a naked seed (cones)

The reproductive adaptations of angiosperms include flowers and fruit 29.3

Angiosperms Ex: Very diverse plants (monocots, dicots) Flower – helps plants reproduce Fruit – helps seed dispersal

Human welfare depends greatly on seed plants 30.4

Plant Uses and Benefits

Plant Uses and Benefits