托福閱讀機經(jīng)背景科學(xué)類:吃蟲植物豬籠草

吃動物的植物，全世界有500多種，其中，以豬籠草的捕蟲器精巧和復(fù)雜。豬籠草大多數(shù)生長在印度洋群島、馬達加斯加、斯里蘭卡、印度尼西亞等潮濕熱帶森林里，我國廣東、云南等省也有這種植物。豬籠草吃蟲，全靠它奇特的葉子

它的葉片中脈伸出去變成卷須，可以攀附著別的東西向上升。卷的頂部生出一個囊狀物，好象奶瓶子一樣，口上有一個蓋，能開也能關(guān)。瓶口邊緣向內(nèi)卷，瓶內(nèi)有半瓶子水液。瓶口內(nèi)壁能分泌又甜又香的蜜汁，貪吃的小昆蟲聞到香味就會爬過去吃蜜。也許就在它們吃得正得意的時候，腳下突然一滑，一頭栽到瓶中，被水液粘住了，再也無法逃命。于是豬籠草得到了一頓美餐。

其它吃蟲植物如茅膏菜、毛氈苔、捕蠅草等，雖然也能捕捉昆蟲，但它們的捕蟲工具，遠不及豬籠草的精巧復(fù)雜。

Pitcher plants are carnivorous plants whose prey-trapping mechanism features a deep cavity filled with liquid known as a pitfall trap. It has been widely assumed that the various sorts of pitfall trap evolved from rolled leaves, with selection pressure favouring more deeply cupped leaves over evolutionary time. However, some pitcher plant genera （such as Nepenthes） are placed within clades consisting mostly of flypaper traps: this indicates that this view may be too simplistic, and some pitchers may have evolved from flypaper traps by loss of mucilage.

Whatever their evolutionary origins, foraging, flying or crawling insects such as flies are attracted to the cavity formed by the cupped leaf, often by visual lures such as anthocyanin pigments, and nectar bribes. The sides of the pitcher are slippery and may be grooved in such a way so as to ensure that the insects cannot climb out. The small bodies of liquid contained within the pitcher traps are called phytotelmata. They drown the insect, and the body of it is gradually dissolved. This may occur by bacterial action （the bacteria being washed into the pitcher by rainfall） or by enzymes secreted by the plant itself. Furthermore, some pitcher plants contain mutualistic insect larvae, which feed on trapped prey, and whose excreta the plant absorbs.[1] Whatever the mechanism of digestion, the prey items are converted into a solution of amino acids, peptides, phosphates, ammonium and urea, from which the plant obtains its mineral nutrition （particularly nitrogen and phosphorus）。 Like all carnivorous plants, they occur in locations where the soil is too poor in minerals and/or too acidic for most plants to be able to grow.

本篇關(guān)鍵詞：

Pitcher plants

carnivorous plants

mucilage

cupped leaf

slippery

grooved

phytotelmata

amino acids

peptides

phosphates

ammonium and urea

nitrogen and phosphorus

以上即為關(guān)于托福閱讀機經(jīng)背景科學(xué)類：會吃蟲子的植物的詳細內(nèi)容，對于同學(xué)們積累托福閱讀機經(jīng)的背景知識有一定幫助，也希望同學(xué)們在日常復(fù)習(xí)中自己也有意識地積累一些托福閱讀背景素材。