那茎秆就像根潜水呼吸管，当植株的绝大部分被淹没在水下时，它仍能保证植物与大气进行气体交换。
Like a snorkel, the elongated stem allows the plant to exchange gases with the atmosphere while most of it is submerged.
植物叶片表皮存在的数目众多的小孔，打开时允许气体自由出入进行交换。
Stoma (pl. stomata) One of a large number of pores in the epidermis of plants through which gaseous exchange occurs.
地下水也含有溶解了的二氧化碳，这些二氧化碳是从空气和从植物根系的气体交换中获得的。
Ground water also contains dissolved carbon dioxide from the air and from the exchange of gases in plant roots.
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