Bryophytes Nonvascular land plants Mosses, liverworts and hornworts Gametophyte (n) is photosynthetic , dominant generation Typically ground-hugging plants (Why?) In this picture the photosynthetic gametophyte is green and the mature sporophyte with sporangium appears brown. Ask students to explain why these plants cannot grow very tall.

Ferns Seedless vascular plants Horsetails and ferns Sporophyte (2n) is dominant generation Most common in damp areas due to flagellated sperm that must swim to reach eggs Ferns and horsetails are in the Phylum Pterophyta and commonly referred to as pterophytes. These plants can grow very tall, but still live in moist environments – why? (vascular tissue for growth, but swimming sperm require water for reproduction) Be sure to mention that the seedless vascular plants that formed the Carboniferous forests eventually became coal.

Gymnosperms “Naked” seeds not enclosed in ovaries Conifers, ginkgos, and cycads Sporophyte (2n) is the dominant generation Seeds are exposed on modified leaves that usually form cones Gymnosperms (the name means “naked seed” and refers to the fact that they do not possess an ovary) are vascular, non-flowering, seed-bearing plants that we typically associate with cones, e.g. pine trees. The ovules of gymnosperms are not protected by the ovary or fruit tissue. A change in anatomy enabled seed plants to grow to great heights. (Lignin! – a term not on the AP exam, but is another example of adaptation to local environment and the resulting adaptive radiation it made possible) The adaptations first appearing in Gymnosperms, pollen and ovules, diminished the requirement of water for fertilization (wind-blown pollen! vs. swimming sperm); allowing these plants to reproduce under a broad range of conditions. The development of seeds with protective coats is a major reason for the success of seed plants. The giant sequoia is one of the largest and oldest living organisms. Some are estimated to be between 1,800 and 2,700 years old.

Angiosperms Flowering plants Pecan trees, roses, peach trees, tomatoes Sporophyte (2n) generation is dominant Flowers and fruit Most abundant of all plant species Angiosperms have reproductive structures in flowers and seeds enclosed in fruits. The name means “seed in a vessel” referring to the presence of an ovary that encloses the seed. The hallmark of angiosperm life cycles is double fertilization. Flower parts are modified leaves and these have diversified to attract animal pollinators, provide food, and prevent self-fertilization. Angiosperms have coevolved with animals. Fruits develop from the ovaries after fertilization and serve to protect seeds and aid in dispersal. Recap the connection between bryophytes, ferns, gymnosperms, and angiosperms focusing on their distinguishing characteristics as plants moved from water to land. You should include a discussion of the great reduction in the gametophyte stage as plants moved onto land.

Plant Structure and Function A simple body plan underlies the diversity of plant forms that exist today. Plants have two vegetative organ systems, the root system and the shoot system. Apical meristems can produce new tissue throughout the plant’s life. Most cells are totipotent, so plants can repair damage. Growth patterns are established in the embryo. Apical meristems and the three tissue systems are established.

Hierarchy of Plant Organization Systems - root and shoot Organs – roots, stems, and leaves . Like animals, plants display a hierarchical organization. The basic anatomy of a vascular plants reflects their ability to draw resources from above and below the ground (the shoot and root systems). Plants rely heavily on both systems for survival. Discuss the interactions between these two systems. Roots are typically not photosynthetic but are dependent on the shoot system for sugars and carbohydrates resulting from photosynthesis. The shoot system is dependent on the root system for the water absorbed from the soil for photosynthesis.

Organ Systems: Another view of the plant organ systems. You do not have to teach the differences between monocot and Eudicot, it just makes a good discussion. Working down the hierarchy from the organismal level to the system level…plants have two vegetative organ systems, the root system and the shoot system. The root system is below the ground and the shoot system is above the ground. Root System – anchors plant, absorbs water and minerals, stores products of photosynthesis. Branching increases surface area for absorption. Shoot System – leaves are the main photosynthetic organs; stems hold leaves up to expose them to sunlight and connect the roots and leaves. Ask students to hypothesize some fundamental similarities and differences between these two systems based on their location above and below the ground.

Organs: Roots Roots – anchor a vascular plant to the soil, absorb minerals and water, and often store carbohydrates

Root Adaptations Each of these evolutionary root adaptations increase plant survival in a given environment. Interesting examples of root adaptations. These are not required knowledge, so you do not have to teach these, but they again make great examples of adaptations to local environments produced via natural selection and are just plain interesting! Prop roots – aerial roots of Hala trees support the tall, top-heavy trees which are found in sandy, unstable soils Storage roots – many plants store food and water in their roots; common beet Pneumatophores – air roots, such as these found on mangroves allow the root system to obtain oxygen which is lacking in the thick mud of intertidal swamps Ask students to hypothesize the purpose of the adaptations from the picture. This information is pretty specific, but these are great examples of evolutionary adaptations allowing success in a given environment. Encourage the students to pick a favorite and be able to explain it in an evolutionary sense.

Organs: Stems the main photosynthetic organs Stems – lift leaves and reproductive structures

Stem Adaptations Some plants have stems with additional functions, such as food storage and asexual reproduction. These are examples of modified stems. None of these are required knowledge, but again, they are pretty interesting  Rhizome – horizontal shoot that grows just below the surface of the ground; vertical shoots emerge from axillary buds Stolon – horizontal shoots that grow along the surface of the ground; “runners” allow asexual reproduction as plantlets form at nodes Tubers - enlarged ends of rhizomes or stolons specialized for storing carbohydrates; “eyes” of potatoes are clusters of axillary buds Bulbs – vertical underground shoots consisting of enlarged bases of leaves that store carbohydrates; note the layers of modified leaves Again, encourage students to adopt a favorite.