1. The ancestors of plants were photosynthetic single-celled organisms that gave rise to plants presumably lacked true roots， stems， leaves， and complex reproductive structures such as flowers.
语言点ers为定语从句修饰single-celled organisms， 从句中ers为过去分词做定语修饰plants。
2. In addition， other lines of evidence support the hypothesis that land plants evolved from ancestral green algae used the same type of chlorophy II and accessory pigments in photosynthesis as do land plants.
语言点 plants为hypothesis的同位语从句，句中plants做主语，n algae为分词结构修饰land plants， used为从句中谓语动词，as do land plants表示类比。
3. Water temperature can fluctuate seasonally or even daily and changing level of rainfall can lead to fluctuations in concentration of chemical in the water or even to period in which the aquatic habitat dries up.
语言点：and连接前后两个并列句。in which the aquatic habitat dries up为定语从句修饰period， even to是lead to的第二个结果。
4. From a plant’s evolutionary view point， however， it was also a land of opportunity， free of competitors and predators and full of carbon dioxide and sunlight （the raw materials for photosynthesis， which are present in far higher concentrations in air than in water）.
语言点：free of competitors and predators and full of carbon dioxide and sunlight中free of and full of为并列形容词修饰a land of opportunity， 句末括号中的内容修饰carbon dioxide and sunlight。
5. They include roots or root like structures， a waxy cuticle that covers the surfaces of leaves and stems and limits the evaporation of water， and pores called stomata in leaves and stems that allow gas exchange but close when water is scarce， thus reducing water loss.
语言点：a waxy evaporation of water，and r loss与root like structures并列。
6. So the most successful groups of land plants are those that evolved methods of fertilized sex cell dispersal that are independent of water and structures that protect developing embryos from dying out.
语言点：that evolved methods of fertilized sex cell dispersal that are independent of water and structures that protect developing embryos from dying out为定语从句修饰those， that are independent of water and structures修饰methods， and structures that protect developing embryos from dying out与methods并列，其中that protect developing embryos from dying out做定语修饰structures。
7. There are two general classes of vegetation： long-lived perennials， which may be succulent and are often dwarfed and woody， and annuals or ephemerals， which have a short life cycle and may form a fairly dense stand immediately after rain.
语言点：which may be succulent and are often dwarfed and woody为定语从句修饰long-lived perennials， which have a short life cycle and may form a fairly dense stand immediately after rain为定语从句修饰annuals or ephemerals。long-lived perennials与annuals or ephemerals二者并列。
8. The tropics contain a larger surface area of land than higher latitudes---a fact that is not always evident when we examine commonly used projections of Earth’s curved surface， since this tends to exaggerate the areas of land in the higher latitudes---and some biogeographers regard the differences in diversity as a reflection of this effect.
语言点：a fact指代The tropics contain a larger surface area of land than higher latitudes所表达的意思，since this tends to中的this指代Earth’s curved surface， as a reflection of this effect中this effect指代The tropics contain a larger surface area of land than higher latitudes。