When the Hawaiian Islands emerged from thesea as volcanoes, starting about five million years ago, they were far removed fromother landmasses. Then, as blazing sunshine alternated with drenching rains,the harsh, barren surfaces of the black rocks slowly began to soften. Windsbrought a variety of life-forms.
Spores light enough to float on the breezeswere carried thousands of miles from more ancient lands and deposited at randomacross 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 singleindividual 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 organicmolecules. The fungi absorb moisture and mineral salts from the rocks, passingthese on in waste products that nourish algae. It is significant that theearliest living things that built communities on these islands are examples ofsymbiosis, a phenomenon that depends upon the close cooperation of two or moreforms of life and a principle that is very important in island communities.
Lichens helped to speed the decompositionof the hard rock surfaces, preparing a soft bed of soil that was abundantlysupplied with minerals that had been carried in the molten rock from the bowelsof Earth. Now, other forms of life could take hold: ferns and mosses (two ofthe most ancient types of land plants) that flourish even in rock crevices.These plants propagate by producing spores–tiny fertilized cells that containall the instructions for making a new plant–but the spore are unprotected byany outer coating and carry no supply of nutrient. Vast numbers of them fall onthe ground beneath the mother plants. Sometimes they are carried farther afieldby water or by wind. But only those few spores that settle down in very favorablelocations can start new life; the vast majority fall on barren ground. By forceof sheer numbers, however, the mosses and ferns reached Hawaii, survived, andmultiplied. Some species developed great size, becoming tree ferns that evennow grow in the Hawaiian forests.
Many millions of years after ferns evolved(but long before the Hawaiian Islands were born from the sea), another kind of floraevolved on Earth: the seed-bearing plants. This was a wonderful biologicalinvention. The seed has an outer coating that surrounds the genetic material ofthe new plant, and inside this covering is a concentrated supply of nutrients.Thus the seed’s chances of survival are greatly enhanced over those of thenaked spore. One type of seed-bearing plant, the angiosperm, includes all formsof blooming vegetation. In the angiosperm the seeds are wrapped in anadditional layer of covering. Some of these coats are hard–like the shell of anut–for extra protection. Some are soft and tempting, like a peach or a cherry.In some angiosperms the seeds are equipped with gossamer wings, like thedandelion and milkweed seeds. These new characteristics offered better ways forthe seed to move to new habitats. They could travel through the air, float in water,and lie dormant for many months.
Plants with large, buoyant seeds—likecoconuts—drift on ocean currents and are washed up on the shores. Remarkablyresistant to the vicissitudes of ocean travel, they can survive prolongedimmersion in saltwater when they come to rest on warm beaches and theconditions are favorable, the seed coats soften. Nourished by their importedsupply of nutrients, the young plants push out their roots and establish theirplace in the sun.
By means of these seeds, plants spread morewidely to new locations, even to isolated islands like the Hawaiian archipelago,which lies more than 2,000 miles west of California and 3,500miles east ofJapan. The seeds of grasses, flowers, and blooming trees made the long trips tothese islands. (Grasses are simple forms of angiosperms that bear their encapsulatedseeds on long stalks.) In a surprisingly short time, angiosperms filled many ofthe land areas on Hawaii that had been bare.
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