3. Table of Contents – pages iii Unit 1: What is Biology? Unit 2: Ecology Unit 3: The Life of a Cell Unit 4: Genetics Unit 5: Change Through Time Unit 6: Viruses, Bacteria, Protists, and FungiViruses, Bacteria, Protists, and Fungi Unit 7: Plants Unit 8: Invertebrates Unit 9: Vertebrates Unit 10: The Human Body

4. Table of Contents – pages vii-xiii Unit 1: What is Biology? Chapter 1: Biology: The Study of Life Unit 2: Ecology Chapter 2: Principles of Ecology Chapter 3: Communities and Biomes Chapter 4: Population Biology Chapter 5: Biological Diversity and Conservation Unit 3: The Life of a Cell Chapter 6: The Chemistry of Life Chapter 7: A View of the Cell Chapter 8: Cellular Transport and the Cell Cycle Chapter 9: Energy in a Cell

5. Table of Contents – pages vii-xiii Unit 4: Genetics Chapter 10: Mendel and Meiosis Chapter 11: DNA and Genes Chapter 12: Patterns of Heredity and Human Genetics Chapter 13: Genetic Technology Unit 5: Change Through Time Chapter 14: The History of Life Chapter 15: The Theory of Evolution Chapter 16: Primate Evolution Chapter 17: Organizing Life’s Diversity

6. Table of Contents – pages vii-xiii Unit 6: Viruses, Bacteria, Protists, and FungiViruses, Bacteria, Protists, and Fungi Chapter 18: Viruses and Bacteria Chapter 19: Protists Chapter 20: FungiFungi Unit 7: Plants Chapter 21: What Is a Plant? Chapter 22: The Diversity of Plants Chapter 23: Plant Structure and Function Chapter 24: Reproduction in Plants

7. Table of Contents – pages vii-xiii Unit 8: Invertebrates Chapter 25: What Is an Animal? Chapter 26: Sponges, Cnidarians, Flatworms, and Roundworms Chapter 27: Mollusks and Segmented Worms Chapter 28: Arthropods Chapter 29: Echinoderms and Invertebrate Chordates

8. Table of Contents – pages vii-xiii Unit 9: Vertebrates Chapter 30: Fishes and Amphibians Chapter 31: Reptiles and Birds Chapter 32: Mammals Chapter 33: Animal Behavior Unit 10: The Human Body Chapter 34: Protection, Support, and Locomotion Chapter 35: The Digestive and Endocrine Systems Chapter 36: The Nervous System Chapter 37: Respiration, Circulation, and Excretion Chapter 38: Reproduction and Development Chapter 39: Immunity from Disease

9. Unit Overview – pages 472-473 Viruses, Bacteria, Protists, and Fungi Viruses and Bacteria Protists Fungi

10. Chapter Contents – page ix Chapter 20 FungiFungi 20.1: What is a fungus?What is a fungus? 20.1: Section CheckSection Check 20.2: The Diversity of FungiThe Diversity of Fungi 20.2: Section CheckSection Check Chapter 20 SummarySummary Chapter 20 AssessmentAssessment

11. Chapter Intro-page 528 What You’ll Learn You will identify the characteristics of the fungi kingdom. You will differentiate among the phyla of fungi.

12. 20.1 Section Objectives – page 529 Identify the basic characteristics of the fungi kingdom. Section Objectives: Explain the role of fungi as decomposers and how this role affects the flow of both energy and nutrients through food chains.

13. Section 20.1 Summary – pages 529-534 Fungi are everywhere—in the air and water, on damp basement walls, in gardens, on foods, and sometimes even between people’s toes. The Characteristics of Fungi

14. Section 20.1 Summary – pages 529-534 Some fungi are large, bright, and colorful, whereas others are easily overlooked. The Characteristics of Fungi Many species grow best in moist environments at warm temperatures between 20°C and 30°C.

15. Section 20.1 Summary – pages 529-534 Fungi used to be classified in the plant kingdom because, like plants, many fungi grow anchored in soil and have cell walls. However, as biologists learned more about fungi, they realized that fungi belong in their own kingdom. The Characteristics of Fungi

16. Section 20.1 Summary – pages 529-534 Although there are a few unicellular types of fungi, such as yeasts, most fungi are multicellular. The structure of fungi The basic structural units of multicellular fungi are their threadlike filaments called hyphae (HI fee) (singular, hypha), which develop from fungal spores.

17. Section 20.1 Summary – pages 529-534 The structure of fungi Spore Germinating Spore Food Source Mycelium

18. Section 20.1 Summary – pages 529-534 There are different types of hyphae in a mycelium. Some anchor the fungus, some invade the food source, and others form fungal reproductive structures. The structure of fungi

19. Section 20.1 Summary – pages 529-534 Unlike plants, which have cell walls made of cellulose, the cell walls of most fungi contain a complex carbohydrate called chitin (KI tun). Chitin gives the fungal cell walls both strength and flexibility. The structure of fungi

20. Section 20.1 Summary – pages 529-534 The structure of fungi Click image to view movie.

21. Section 20.1 Summary – pages 529-534 In many types of fungi, cross walls called septa (singular, septum) divide hyphae into individual cells that contain one or more nuclei. Septa are usually porous, allowing cytoplasm and organelles to flow freely and nutrients to move rapidly from one part of a fungus to another. Inside hyphae

22. Section 20.1 Summary – pages 529-534 Inside hyphae Septum Cytoplasm Cell Wall Nuclei

23. Section 20.1 Summary – pages 529-534 Some fungi consist of hyphae with no septa. Cytoplasm Cell Wall Nuclei Inside hyphae

24. Section 20.1 Summary – pages 529-534 Under a microscope, you see hundreds of nuclei streaming along in a continuous flow of cytoplasm. Inside hyphae As in hyphae with septa, the flow of cytoplasm quickly and efficiently disperses nutrients and other materials throughout the fungus.

25. Section 20.1 Summary – pages 529-534 Fungi can be harmful. Some cause food to spoil. Some cause diseases, and some are poisonous. However, they play an important and beneficial role. Adaptations in Fungi In a world without fungi, huge amounts of wastes, dead organisms, and debris, which consist of complex organic substances, would litter Earth.

26. Section 20.1 Summary – pages 529-534 Many fungi, along with some bacteria and protists, are decomposers. They break down complex organic substances into raw materials that other living organisms need. Adaptations in Fungi

27. Section 20.1 Summary – pages 529-534 Fungi are heterotrophs, and they use a process called extracellular digestion to obtain nutrients. In this process, food is digested outside a fungus’s cells, and the digested products are then absorbed. How fungi obtain food

28. Section 20.1 Summary – pages 529-534 Chemicals released by hyphae digest dead materials. Hyphae absorb the digested food. How fungi obtain food

29. Section 20.1 Summary – pages 529-534 For example, as some hyphae grow into the cells of an orange, they release digestive enzymes that break down the large organic molecules of the orange into smaller molecules. How fungi obtain food

30. Section 20.1 Summary – pages 529-534 These small molecules diffuse into the fungal hyphae and move in the free-flowing cytoplasm to where they are needed for growth, repair, and reproduction. How fungi obtain food

31. Section 20.1 Summary – pages 529-534 A fungus may be a saprophyte, a mutualist, or a parasite depending on its food source. Saprophytes are decomposers and feed on waste or dead organic material. Different feeding relationships Mutualists live in a symbiotic relationship with another organism, such as an alga.

32. Section 20.1 Summary – pages 529-534 Parasites absorb nutrients from the living cells of their hosts. Different feeding relationships

33. Section 20.1 Summary – pages 529-534 Different feeding relationships Fungal hypha Haustorium Host cell

34. Section 20.1 Summary – pages 529-534 Depending on the species and on environmental conditions, a fungus may reproduce asexually or sexually. Fungi reproduce sexually by fragmentation, budding, or producing spores. Reproduction in Fungi

35. Section 20.1 Summary – pages 529-534 In fragmentation, pieces of hyphae that are broken off of a mycelium grow into new mycelia. Fragmentation and budding

36. Section 20.1 Summary – pages 529-534 The unicellular fungi called yeasts often reproduce by a process called budding—a form of asexual reproduction in which mitosis occurs and a new individual pinches off from the parent, matures, and eventually separates from the parent. Fragmentation and budding Yeast budding

37. Section 20.1 Summary – pages 529-534 Most fungi produce spores. When a fungal spore is transported to a place with favorable growing conditions, a threadlike hypha emerges and begins to grow, eventually forming a new mycelium. Reproducing by spores The mycelium becomes established in the food source.

38. Section 20.1 Summary – pages 529-534 Bread Mold Hyphae Sporangium Spores Reproducing by spores

39. Section 20.1 Summary – pages 529-534 One important criterion for classifying fungi into divisions is their patterns of reproduction, especially sexual reproduction, during the life cycle. Reproducing by spores Many fungi can produce two types of spores—one type by mitosis and the other by meiosis—at different times during their life cycles.

40. Section 20.1 Summary – pages 529-534 Many adaptive advantages of fungi involve spores and their production. The adaptive advantages of spores

41. Section 20.1 Summary – pages 529-534 The adaptive advantages of spores First, the sporangia protect spores and, in some cases, prevent them from drying out until they are ready to be released. Second, most fungi produce a large number of spores at one time.

42. Section 20.1 Summary – pages 529-534 Producing so many spores increases the germination rate and improves the species survival chances. The adaptive advantages of spores Finally, fungal spores are small and lightweight and can be dispersed by wind, water, and animals such as birds and insects.

43. Section 1 Check Question 1 Hyphae develop from _______. D. rhizoids C. cellulose B. chitin A. spores

44. Section 1 Check The answer is A, spores. Bread Mold Hyphae Sporangium Spores

45. Section 1 Check Question 2 A mycelium is composed of _______. D. conidiophores C. sporangia B. hyphae A. spores The answer is B, hyphae.

46. Section 1 Check Question 3 What are three different functions that hyphae can perform in a mycelium? Answer Some hyphae anchor the fungus, some invade the food source, and others form fungal reproductive structures.

47. Section 1 Check Question 4 Explain how a fungus performs extracellular digestion. Answer Hyphae grow into the cells of the food source, releasing digestive enzymes that break down large organic molecules into smaller molecules. These molecules move in the free- flowing cytoplasm to where they are needed for growth, repair, and reproduction.

48. Section 1 Check Question 5 Which type of fungi lives in a symbiotic relationship with another organism? D. decomposers C. mutualists B. saprophytes A. parasites The answer is C, mutualists.

49. 20.2 Section Objectives – page 535 Section Objectives Distinguish among the ways spores are produced in zygomycotes, ascomycotes, and basidiomycotes. Identify the four major phyla of fungi. Summarize the ecological roles of lichens and mycorrhizae.

50. Section 20.2 Summary – pages 535-543 You have probably seen Rhizopus stolonifer, a common bread mold. Zygomycotes

51. Section 20.2 Summary – pages 535-543 Zygomycotes Rhizopus is probably the most familiar member of the phylum Zygomycota (zy goh mi KOH tuh). Many other members of about 1500 species of zygomycotes are also decomposers.

52. Section 20.2 Summary – pages 535-543 Zygomycotes reproduce asexually by producing spores. Zygomycotes They produce a different type of spore when they reproduce sexually. The hyphae of zygomycotes do not have septa that divide them into individual cells.

53. Section 20.2 Summary – pages 535-543 When a Rhizopus spore settles on a moist piece of bread, it germinates and hyphae begin to grow. Growth and asexual reproduction Some hyphae called stolons (STOH lunz) grow horizontally along the surface of the bread, rapidly producing a mycelium.

54. Section 20.2 Summary – pages 535-543 Growth and asexual reproduction Some other hyphae form rhizoids (RI zoydz) that penetrate the food and anchor the mycelium in the bread. Rhizoids secrete enzymes needed for extracellular digestion and absorb the digested nutrients.

55. Section 20.2 Summary – pages 535-543 Growth and asexual reproduction Asexual reproduction begins when some hyphae grow upward and develop sporangia at their tips. Asexual spores develop in the sporangia. When a sporangium splits open, hundreds of spores are released.

56. Bread Mold Hyphae Sporangium Spores Section 20.2 Summary – pages 535-543 Growth and asexual reproduction

57. Section 20.2 Summary – pages 535-543 Producing zygospores When zygomycotes reproduce sexually, they produce zygospores (ZI guh sporz), which are thick-walled spores that can withstand unfavorable conditions.

58. Section 20.2 Summary – pages 535-543 Producing zygospores Sexual reproduction in Rhizopus occurs when haploid hyphae from two compatible mycelia, called plus and minus mating strains, grow together and fuse. Where the haploid hyphae fuse, they each form a gametangium (ga muh TAN ghee uhm), a structure containing a haploid nucleus.

59. Section 20.2 Summary – pages 535-543 Producing zygospores Asexual ReproductionSexual Reproduction Rhizoids Stolon + Mating strain (n) - Mating strain (n) Gametangia Spores (n) Sporangia Sporangium Hypha Zygospore Meiosis Spores (n) Germination

60. Section 20.2 Summary – pages 535-543 Producing zygospores When the haploid nuclei of the two gametangia fuse, a diploid zygote forms. The zygote develops a thick wall, becoming a dormant zygospore.

61. Section 20.2 Summary – pages 535-543 Producing zygospores When environmental conditions are favorable, the zygospore absorbs water, undergoes meiosis, and germinates to produce a hypha with a sporangium. Each haploid spore formed in the sporangium can grow into a new mycelium.

62. Section 20.2 Summary – pages 535-543 Ascomycotes The Ascomycota is the largest phylum of fungi, containing about 30,000 species. The ascomycotes are also called sac fungi. Both names refer to tiny saclike structures, each called an ascus, in which the sexual spores of the fungi develop. Because they are produced inside an ascus, the sexual spores are called ascospores.

63. Section 20.2 Summary – pages 535-543 Ascomycotes During asexual reproduction, ascomycotes produce a different kind of spore. Fungal hyphae grow up from the mycelium and elongate to form conidiophores (kuh NIH dee uh forz). Conidiophores

64. Section 20.2 Summary – pages 535-543 Chains or clusters of asexual spores called conidia develop from the tips of conidiophores. Conidiophores Ascomycotes

65. Section 20.2 Summary – pages 535-543 Important ascomycotes Sac fungi are familiar to farmers and gardeners because they cause plant diseases such as apple scab and ergot of rye. Not all sac fungi have a bad reputation. Ascomycotes can have many different forms.

66. Section 20.2 Summary – pages 535-543 Important ascomycotes Morels and truffles are two edible members of this phylum. Morels

67. Section 20.2 Summary – pages 535-543 Important ascomycotes Perhaps the most economically important ascomycotes are the yeasts. Yeasts are unicellular sac fungi that rarely produce hyphae and usually reproduce asexually by budding. Yeasts are anaerobes and ferment sugars to produce carbon dioxide and ethyl alcohol.

68. Section 20.2 Summary – pages 535-543 Important ascomycotes Because yeasts produce alcohol, they are used to make wine and beer. Other yeasts are used in baking because they produce carbon dioxide, the gas that causes bread dough to rise and take on a light, airy texture.

69. Section 20.2 Summary – pages 535-543 Important ascomycotes Yeasts are also important tools for research in genetics because they have large chromosomes. A vaccine for the disease hepatitis B is produced by splicing human genes with those of yeast cells. Because yeasts multiply rapidly, they are an important source of the vaccine.

70. Section 20.2 Summary – pages 535-543 Basidiomycotes Mushrooms, puffballs, stinkhorns, bird’s nest fungi, and bracket fungi are all basidiomycotes. Shelf fungi

71. Section 20.2 Summary – pages 535-543 Basidia and basidiospores Cap Gills Hyphae Spores Spore-producing part

72. Section 20.2 Summary – pages 535-543 Basidia and basidiospores A basidiomycote, such as a mushroom, has a complex reproductive cycle. What you call a mushroom is a reproductive structure of the fungus. Most of the fungus is underground and not visible.

73. Section 20.2 Summary – pages 535-543

74. Deuteromycotes There are about 25,000 species of fungi classified as deuteromycotes, which have no known sexual stage in their life cycle. Although the deuteromycotes may only be able to reproduce asexually, another possibility is that their sexual phase has not yet been observed by mycologists, biologists who study fungi.

75. Section 20.2 Summary – pages 535-543 Diverse deuteromycotes If you’ve ever had strep throat, pneumonia, or other kinds of bacterial infection, your doctor may have prescribed penicillin—an antibiotic produced from a deuteromycote that is commonly seen growing on fruit.

76. Section 20.2 Summary – pages 535-543 Diverse deuteromycotes Other deuteromycotes are used in the making of foods, such as soy sauce and some kinds of blue-veined cheese.

77. Section 20.2 Summary – pages 535-543 Diverse deuteromycotes Still some deuteromycotes are used commercially to produce substances such as citric acid, which gives jams, jellies, soft drinks, and fruit-flavored candies a tart taste.

78. Section 20.2 Summary – pages 535-543 Mutualism: Mycorrhizae and Lichens Certain fungi live in a mutualistic association with other organisms. Two of these mutualistic associations that are also symbiotic are called mycorrhizae and lichens.

79. Section 20.2 Summary – pages 535-543 Mycorrhizae A mycorrhiza (my kuh RHY zuh) is a mutualistic relationship in which a fungus lives symbiotically with a plant. Most of the fungi that form mycorrhizae are basidiomycotes, but some zygomycotes also form these important relationships.

80. Section 20.2 Summary – pages 535-543 Mycorrhizae How does a plant benefit from a mycorrhizal relationship? Fine, thread-like hyphae grow harmlessly around or into the plant’s roots. The hyphae increase the absorptive surface of the plant’s roots, resulting in more nutrients entering the plant.

81. Section 20.2 Summary – pages 535-543 Mycorrhizae Phosphorus, copper, and other minerals in the soil are absorbed by the hyphae and then released into the roots. In addition, the fungus also may help to maintain water in the soil around the plant. In turn, the mycorrhizal fungus benefits by receiving organic nutrients, such as sugars and amino acids, from the plant.

82. Section 20.2 Summary – pages 535-543 Mycorrhizae Plants of a species that have mycorrhizae grow larger and are more productive than those that don’t. In fact, some species cannot survive without mycorrhizae. Lady slipper orchid

83. Section 20.2 Summary – pages 535-543 Lichens It’s sometimes hard to believe that the orange, green, and black blotches that you see on rocks, trees, and stone walls are alive.

84. Section 20.2 Summary – pages 535-543 Lichens A lichen (LI kun) is a symbiotic association between a fungus, usually an ascomycote, and a photosynthetic green alga or a cyanobacterium, which is an autotroph.

85. Section 20.2 Summary – pages 535-543 Lichens The fungus portion of the lichen forms a dense web of hyphae in which the algae or cyanobacteria grow. Together, the fungus and its photosynthetic partner form a structure that looks like a single organism.

86. Section 20.2 Summary – pages 535-543 Lichens Lichens need only light, air, and minerals to grow. The photosynthetic partner provides the food for both organisms. The fungus, in turn, provides its partner with water and minerals that it absorbs from rain and the air, and protects it from changes in environmental conditions.

87. Section 20.2 Summary – pages 535-543 Lichens There are about 20,000 species of lichens. Found worldwide, lichens are pioneers, being among the first to colonize a barren area.

88. Section 20.2 Summary – pages 535-543 Lichens The fungus readily absorbs materials from the air. Without the fungal part of a lichen, the photosynthetic partner also dies. If pollutants are present, they kill the fungus. Not only are lichens pioneers, but they are also indicators of pollution levels in the air.

89. Section 20.2 Summary – pages 535-543 Origins of Fungi Zygomycotes 1500 species Basidiomycotes 25,000 species Deuteromycotes 25,000 species Ascomycotes 30,000 species Lichens 20,000 species Protists Archaebacteria Eubacteria Species numbers are approximate and subject to change pending discoveries or extinctions.

90. Section 2 Check According to the following figure, which method is NOT used by fungi to reproduce asexually? Question 1

91. Section 2 Check A. producing zygospores B. fragmentation Asexual ReproductionSexual Reproduction Rhizoids Stolon + Mating strain (n) - Mating strain (n) Gametangia Spores (n) Sporangia Sporangium Hypha Zygospore Meiosis Germination Spores (n)

92. Asexual ReproductionSexual Reproduction Rhizoids Stolon + Mating strain (n) - Mating strain (n) Gametangia Spores (n) Sporangia Sporangium Hypha Zygospore Meiosis Germination Section 2 Check C. budding D. producing spores Spores (n)

93. Asexual ReproductionSexual Reproduction Rhizoids Stolon + Mating strain (n) - Mating strain (n) Gametangia Spores (n) Sporangia Sporangium Hypha Zygospore Meiosis Germination Spores (n) Section 2 Check The answer is A, producing zygospores.

94. Section 2 Check The mushrooms you typically eat make up what part of the fungus? Question 2 Answer The mushrooms you typically eat make up the reproductive structure of fungi.

95. Section 2 Check What is the difference between a sporangium and a zygospore? Question 3 A zygospore is a diploid zygote surrounded by a thick wall. A sporangium is a structure containing many haploid spores. Answer

96. Section 2 Check Are gametangia a part of sexual or asexual reproduction in zygomycotes? Question 4 Answer Gametangia are part of the sexual reproductive phase of zygomycotes. Each gametangium contains a haploid nucleus that forms a diploid zygote when it fuses with the haploid nucleus of another gametangium.

97. Section 2 Check The sporangium of a zygomycote is analogous to what in an ascomycote? Question 5 D. conidia C. conidiophore B. ascospore A. ascus

98. Section 2 Check The answer is C, conidiophore.

99. Chapter Summary – 20.1 The structural units of a fungus are hyphae, which grow and form a mycelium. What is a fungus? Fungi are heterotrophs that carry out extracellular digestion. A fungus may be a saprophyte, a parasite, or a mutualist in a symbiotic relationship with another organism.

100. Chapter Summary – 20.1 Many fungi produce both asexual and sexual spores. One criterion for classifying fungi is by their patterns of reproduction, especially sexual reproduction, during the life cycle. What is a fungus?

101. Chapter Summary – 20.2 Zygomycotes form asexual spores in a sporangium. They reproduce sexually by producing zygospores. The Diversity of Fungi Ascomycotes reproduce asexually by producing spores called conidia and sexually by forming ascospores. In basidiomycotes, sexual spores are produced on club-shaped structures called basidia.

102. Chapter Summary – 20.2 Deuteromycotes may reproduce only asexually. The Diversity of Fungi Fungi play an important role in decomposing organic material and recycling the nutrients on Earth.

103. Chapter Summary – 20.2 Certain fungi associate with plant roots to form mycorrhizae, a symbiotic relationship between a fungus and a plant. The Diversity of Fungi A lichen, a symbiotic association of a fungus and an alga or cyanobacterium, survives in many inhospitable habitats.

104. Chapter Assessment Question 1 An example of a fungal infection from a dermatophyte is _______. D. athlete’s foot C. dry rot B. black stem rust A. rye ergot

105. The answer is D. A dermatophyte fungus invades skin, nails, and hair. Chapter Assessment

106. Question 2 Morel mushrooms and truffles are members of which phylum? D. Deuteromycotes C. Basidiomycotes B. Zygomycotes A. Ascomycotes

107. The answer is A, Ascomycotes. Morels Chapter Assessment

108. Question 3 What fungus is important in the production of wine and bread? D. corn smut C. yeast B. black bread mold A. Penicillium

109. The answer is C, yeast. Chapter Assessment

110. Question 4 Fungi that have cup shapes are most likely _______. D. Deuteromycotes C. Basidiomycotes B. Ascomycotes A. Zygomycotes The answer is B, Ascomycotes.

111. Chapter Assessment Question 5 Where do basidiomycotes get their common name, club fungi? Answer Their common name comes from their club-shaped hyphae called basidia.

112. Chapter Assessment Question 6 In basidiomycotes, the basidia are located in the _______. D. basidiospores C. mycelium B. stipe A. gills

113. The answer is A, gills. Cap Gills Hyphae Spores Spore-producing part Chapter Assessment

114. Question 7 Which of the following pairs is NOT related? D. Penicillin – basidiomycotes C. black bread mold – zygomycotes B. blue-veined cheese – deuteromycotes A. bread rising – ascomycotes The answer is D.

115. Chapter Assessment Question 8 How is a lichen relationship different from a mycorrhizal relationship? Answer A lichen is a symbiotic relationship between a fungus and an alga or cyanobacterium. A mycorrhiza is a relationship between a fungus and a plant.

116. Chapter Assessment Question 9 How are lichens indicators of pollution levels in the air?

117. Lichens readily absorb materials from the air. If pollutants are present, they kill the fungus, which also kills the photosynthetic partner. Chapter Assessment

118. Question 10 Which of the following is NOT a plant pathogen? D. rust C. ringworm B. ergot A. smut The answer is C. Ringworm is a human pathogen.

119. Photo Credits PhotoDisc Joseph O'Brein/Northeastern Area Forest Services/USDA Mark Thayer Photography Carolina Biological Supply Company Alan Wheals, Dept. of Biology and Biochemistry, University of Bath

120. Photo Credits Systematic Botany and Mycology Laboratory, Agricultural Research Service, U.S. Department of Agriculture Corbis First Image Digital Stock Alton Biggs

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