文勇的新托福黄金&ccedil

obsidianobtainedbytheolmecsoriginatednearteotihuac

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Unformatted text preview: 在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在 Wildman 在 Niles 在在在在在在在在在在在在“在在在在在在在在在在在在 在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在” Wildman 在 Niles 在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在 Zeichner 在 Liston(1987)在在在在在在在在在在在在在在在在在在在在在在在在在在 在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在 Jaworski,1993在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在 在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在在 THE ARRIVAL OF PLANT LIFE IN HAWAII When the Hawaiian islands emerged from the sea as volcanoes, starting about five million years ago, they were far removed from other landmasses. Then, as blazing sunshine alternated with drenching rains, the harsh, barren surfaces of the black rocks slowly began to soften. Winds brought a variety of life­forms. Spores light enough to float on the breezes were carried thousands of miles from more ancient lands and deposited at random across the bare mountain flanks. A few of these spores found a toehold on the dark, forbidding rocks and grew and began to work their transformation upon the land. Lichens were probably the first successful flora. These are not single individual plants; each one is a symbiotic combination of an alga and a fungus. The algae capture the Sun's energy by photosynthesis and store it in organic molecules. The fungi absorb moisture and mineral salts from the rocks, passing these on in waste products that nourish algae. It is significant that the earliest living things that built communities on these islands are examples of symbiosis, a phenomenon that depends upon the close cooperation of two or more forms of life and a principle that is very important in island communities. Lichens helped to speed the decomposition of the hard rock surfaces, preparing a soft bed of soil that was 277 Mail@liuwenyong.com 在在在在在在 www.liuwenyong.com 在在在在在在在在在在在在在在在,在在在在在在在在在在 abundantly supplied with minerals that had been carried in the molten rock from the bowels of Earth. Now, other forms of life could take hold: ferns and mosses (two of the most ancient types of land plants) that flourish even in rock crevices. These plants propagate by producing spores­tiny fertilized cells that contain all the instructions for making a new plant­but the spores are un...
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