3 What constitutes a plant? Plants are:MulticellularEukaryotesPhotosynthetic autotrophsAlgae may also have these characteristics.Plants appear to have developed from algae.Other features that plants and algae have in common:Presence of chrolophyll b as an accessory pigmentCellulose cell wallsStarch as storage product of surplus carbohydratesPlants occur both on land and in water. Algae only in the presence of water.
4 29.4 Where is the line dividing land plants from algae? Three possible plant kingdoms?Embryophytes: Plants with embryos
5 Figure 29.7 Some highlights of plant evolution Walled spores toughened by sporopolleninMulticellular, dependent embryosApical meristems (root, shoot)Presence of a waxy cuticle[See book p ]
6 29.5. Walled spores produced in sporangia. Spores are haploid reproductive cells that can grow into gametophytes (n) by mitosis. Sporopollenin makes the walls of spores very tough and protects them against dehydrationMulticellular, dependent embryosDevelop from zygotes that are retained within tissue from the female parent
9 Figure 3.3 Vascular tissue – support against gravity and transport system in plants PhloemCambiumXylem: Water conducting cellsLignin: Hard material embedded in cellulose cell walls for structural support
10 Figure 29.5 Alternation of generations: a generalized scheme
11 A hypothetical mechanism for the origin of alternation of generations in the ancestor of plants
25 Sphagnum, or peat moss: Peat bog in Oneida County, Wisconsin (top), close-up of Sphagnum (bottom left), Sphagnum "leaf" (bottom right)
26 A peat moss bog in Norway Carbon reservoir may help stabilize global atmospheric CO2
27 29.11. More than 2000-year old bog mummy preserved in acid, oxygen poor Sphagnum wetlands Peat, partially decayed organic material, harvested from peat moss (Sphagnum) wetlands. Decomposition is slow due to cold temperatures, acid conditions and little oxygen.
44 Heterospory: The sporophyte has two types of sporangia that produce two types of spores, which develop into either female or male unisexual gametophytes.Spores:Megaspore, developing into a female gametophyte, which will produce an eggMicrospore, developing into a smaller male gametophyte, which produces sperm
45 Which of the following is TRUE of seedless vascular plants? They produce many spores, which are really the same as seeds.Seedless vascular plants are all heterosporous.Whole forests were dominated by large, vascular seedless plants more than 300 million years ago.The few seedless vascular plants still living are large and rare.None of the above are true. Vascular plants never form seeds.
46 Chapter 29 –Review (p. 616)Concept Land plants evolved from green algaeConcept Mosses and other non- vascular plants have life cycles dominated by gametophytesConcept Ferns and other seedless vascular plants were the first plants to grow tall