秋天的叶子英语怎么说热门20篇

时令刚刚过了秋分，就突然增加了一些凉意。午后来到公园散步，仿佛觉得天比以前更高远了一些。回头望去。哦，秋色更浓了。

校园里的樟树四季常青，偶尔也有些发黄的叶子。在每个季节里，樟树叶子有一股清香味，让人心旷神怡。银杏的叶子，一到秋天，便变得金黄金黄的，每一片都是一面完整的小扇子。银杏树上，一片树叶缓缓的飞落下来，他先转了两圈，又翻了两个筋斗，然后平静的落进了小河里，这完美的“跳水”赢得了同伴的掌声。我捞起那片银杏叶，仔细的看着。银杏叶是扇形的，就像一条精致的短裙。叶尖已经变成了金黄色，好像一层金子在上面。

我轻轻拾起一片枫叶，那红丹丹的叶面上有着清晰的叶脉，边缘长出均匀的锯齿，样子虽像五指伸开的小手，但颜色却像一团燃烧的火焰。写到这儿，我不禁想起了杜甫的那句“停车坐爱枫林晚，霜叶红于二月花”的千古名句。顽皮的风儿，请你轻些儿跑过我的夜晚，门前的梧桐树叶，已荷不起你日渐肥硕的身体，她们从枝头跌落的声音，让我脆弱的房屋战栗不已。可爱的风，你是谁遗失的孩子?夜已深入骨髓。请不要敲击我单薄的房门，把你的手给我吧，让我引领你，穿过我的梦幻森林，抵达你可爱的故乡。让那些年轻的梧桐叶儿，说完她们在秋天疯长的事。

夕阳西下，树叶摩擦的声音交织成美妙的交响曲，仿佛在与我们依依惜别。多美的秋天啊!多美的秋天的树叶啊!这彩色的叶子将永远刻在我的脑海里，难以忘记。

秋姑娘迈着轻盈的脚步，轻轻地来到人间，那一片片独具特色的树叶全是她的杰作。

我在公园里散步，一进公园，就看到一团火红色，我走近一看，原来是棵枫树啊！一阵微风刮来，把枫叶吹地像一只只蝴蝶在天空中翩翩起舞，我捡起一片枫叶，仔细地观察，枫叶中不只有红色，还夹着几片绿色的呢！大概是秋姑娘忘记给这几片枫叶涂上颜色了吧。它的背面摸上去硬硬的，不像其它树叶摸上去软软的，它的根是红中带一点绿又带一点黄的，它尖尖的头深红色的，再入底下看是红色的，酒红色的，浅红色的……枫树叶子，不像别的树叶那样张扬，再仔细看上一眼，枫叶的形状多么像一只小手掌。秋风吹来，“小手掌”不停地摆动着，像是在欢迎秋姑娘的到来。

远远望去，枫叶就像一团团燃烧的火焰，把大地点缀得分外漂亮。

人们见到了枫叶都会小心翼翼地把它摘下来包好。因为它代表着幸福、吉祥、如意！

在丰富多彩的秋天，有着许多我喜欢的东西，可是我最爱这秋天的树叶，因为它是秋姑娘精心准备送给我们的礼物！

I like you in the fall, because you put a lot of harvest fruit are put on a new dress, because you let the world is full of laughter, because you make the world become colorful.

Field, the rice is laughing waist, a golden corn round like a fat doll, waiting for the farmer uncle to take me home.

Orchard, one of the oranges are bowed his head and said; farmers uncle, why do not you pick me, is not I am not good ah, chestnut are people holding a stick to fight down, and some people brought stew The

The woods, ginkgo trees and plane trees have fallen leaves, flying in the air, as if a girl dancing in the beautiful dance.

Garden, full of sweet-scented osmanthus exudes fragrance, chrysanthemum, sweet-scented osmanthus are open colorful, mix, the garden suddenly became a flower ocean.

Some students in the throwing shot, and some in the rope skipping, and some students in the running it cheerleaders are also cheering for the students, some write the name of the students; some of the students in the school, the school is holding the game Write a class of refueling. The campus is so hot

This is a beautiful and charming autumn, I love you, fall.

Annual the autumn, we can come to here, the ginkgo that admires the autumn forest.

Stands in Lin Bian, scan widely looks, grove hope to be less than a head. Ginkgo tree is lofty and forceful, the sky continuously. The branches and leaves on crown of a tree is very dense, mutual crisscross is worn, formed a natural Lin Yin corridor. Sunshine asperses aureate ray to the earth through flourish branches and leaves, the shadow of branches and leaves is mirrorred go up, formed the facula of alternate with of a lot of light and shade. Aureate sunshine is illuminated on small grass, also set to small grass went up a shining Phnom Penh.

An autumn wind has blown leaf swirls from branch the ground waves fall down, some resembles a young fan yellow, hitting come back face of straight be born, some is in like a flock of golden butterfly forest flutter, really extremely beautiful. There is thick ginkgo part of a historical period everywhere in ginkgo forest, have a plenty of emerald, have a plenty of golden color, still have a plenty of olivine alternate with; Some leaf are general like cup mouth big, the small thumb armour with me builds similar volume. No matter be of what color, it is how big leaf, be sector.

I walk in incomputable small " fan " on, feel loosen again like stepping to go up in blanket soft. Suddenly, I feel to there is below the foot hard hard dot, raise a foot to look, ah! It is the small ginkgo fruit of a round lacteal yellow so. Sough of an autumn wind blows ginkgo tree is shaking off outfit of a suit gold in autumn wind, so good-looking, so Orphean: "Rustle, rustle " .

The vastness of the blue sky floating in the blossoming white flawless clouds. Autumn, sorghum lifted the torch, boundless soybeans shake the bells. Autumn with a golden, walked the pace of light, quietly came to earth.

Autumn, gently blowing, sorghum wheat yellow. Buds of red cherries are dry, and the remaining red one. Dense leaves of soybeans, looking ahead, burnt yellow. In the countryside, the house in front of the red hot pepper, corn stick, very beautiful. Autumn, this fall artist, will be dotted with colorful autumn.

The sun slowly rising, glow to the surrounding radiation, slowly expanding, to the sky on the start, the whole sky dyed. In the sun, the white clouds dyed red, green mountains dyed red, river dyed purple, the sky as if the fire. The sun, the fall of the artist, will fall into a huge colorful painting.

You see that blue sky, clear sky a Bi, Lang Lang heaven and earth, like pondering smooth sapphire, and like the delicate texture of the blue silk. The sun converges from the glare of light, into a golden CD. Blossoming clouds, the more drift slowly, a touch of clouds, and gradually transparent. Ups and downs of the mountains, like Hongbo filled. I am surprised that the river is green, like an emerald, Oh! "Emerald" in the flow!

Every autumn wind comes, colorful, mix and match. Sun, blue sky, white clouds, river water, seemingly ordinary, they dotted the fall, how can the autumn colorful? Autumn by them, they are the fall of the artist!

What a colorful world of the fall,this is a credit to the leaves,they have red and green,the autumn dress up like a large garden.

red maple leaves,like palms,just five piece children.Leaves a small number of prominent teeth,the base of the heart-shaped,dark green to dark green above to below the axillary vein has hair sense,the edge is also trimmed with lace irregular.Bark grayish brown,with the old growth,the surface grooves and scales.Maple leaves,autumn brings a festive and warm.

holly tree is the symbol of vitality,crown thriving,flourish.Leaves oval,pointed at both ends,like the two tilt of the boat.Stem and leaf surface veins is very clear,long from bottom to top,from coarse to fine.The front of dark green leaves,very smooth,negative light green,because there are many prominent veins and coarse stems.Holly leaves have wavy lines on the edge of the same jagged,but not scratchy.

the campus,red maple,holly green,a passionate,full of vitality,this is really the mental outlook of our young pioneers it!I love autumn,I love the fall on campus.

我的世界的秋天,这是一个信用的叶子,他们有红色和绿色,秋天打扮像一个大花园.

红色的枫叶,像手掌,只是五个孩子.叶少数突出的牙齿,该基地的心形,暗绿色至暗绿色以上低于腋静脉有毛,边缘还镶着花边的不规则.树皮淡灰棕色,随着月龄的增长,表面沟槽和尺度.秋天的枫叶,带来了喜庆和温暖.

冬青树是生命力的象征,冠兴旺,繁荣.叶椭圆形,两端尖,像两只倾斜的船.茎和叶表面的纹路很清楚,从底部到顶部,从粗到细.正面深绿色的叶子,很光滑,负光绿色,因为有许多突出的静脉和粗茎.冬青叶有波浪纹边缘的锯齿,但不痒.

校园,枫叶红,绿冬青,热情,充满活力,这是真正的精神面貌我们少先队员了!我爱秋天,我爱秋天的校园。

秋，已悄悄来临；叶，已静静等待；捡起一片银杏树叶，去感受秋天的气息。

捡到一片银杏树叶，细细观察。似扇似鱼尾的叶片，像秋天的精灵。它非常勇敢，在寒风中，它变成一把扇子，把风扇的更大；在波浪滔滔的湖中，它变成了一条断了尾的鱼，在冰冷的湖中艰难地游动。它有着十分美丽的色彩，披着绿衣裳的身体让它充满生机，而边缘似黄丝带的纹，让它显得苍老而又有点神秘。变得不再坚硬的身体，已没有了春天的活力，想去飞翔，却无力可为；想畅游天空，却没有了可靠的翅膀。

再细细闻一闻树叶，虽有一丝似有非有的香味，但大体上已经没有了春天的芳香。轻轻抚一下，觉得像抚在丝绸上，叶上似被雕刻家精心刻上的纹路，是那样的清晰；细细品尝，舌尖一丝苦味，足够体现叶子的苦涩，意犹未尽，可以顿时让人头脑清醒。

在绿的，黄的各种银杏叶中，有一股很浓的秋味，但大多数都是生命之灯接近尾声的枯叶，秋天的来临毫不留情地夺走了它们的生命，枯萎的叶子变成极佳的肥料滋养着树干，为来年新叶片的成长贡献着自己最后一份力量。

秋天到，树叶落，果实一大筐，人人乐开花。银杏树叶很坚强，齐心协力抗风寒！

大自然赐予春天鸟语花香，赐予夏天欣欣向荣，赐予冬天洁白无暇，它还赐予秋天精灵的化身一叶。

清晨，朝霞透过金黄的银杏叶洒落在地上，这时银杏叶亮闪闪的，就像一把把小巧的，洒着荧光粉的蒲扇。我走出房门，来到银杏树下，秋风一吹，叶子落下来，像无数位身穿金黄色舞裙的仙子在比舞，我看着，仿佛自己也是一位仙女，情不自禁地在树下翩翩起舞，一片叶子落到我的手上，我停止了舞蹈，细细的端详着手上的这片银杏叶，它还没完全退去绿衣裳，像一把淡绿的小扇子，我忍不住低头闻了闻，一阵阵清香扑鼻而来，我顿时神清气爽，精神多了，我又摸了摸，感觉就像摸在丝绸上，那样地光滑，冰凉，我小心翼翼的把它收藏起来，让秋色永远留在我心中，

我爱秋天，但我更爱秋天的落叶。

我爱金色的秋天，但我更爱那秋天的树叶。傍晚夕阳西下时，我和妈妈在河堤边漫步，时而我抬起头来看看路边的树叶，只见那树叶真是千姿百态、种类繁多呀!

先说说红背桂吧!它摸上去很柔软，形状呈长筒状，树叶的边缘略带了一点轻微而又稀疏的锯齿。红背桂一根主叶脉支撑着整张叶片，又从主叶脉向两侧对称分布着许多分枝叶脉;红背桂的叶柄细长，而且还是深红色。最有趣的是红背桂一进入秋天时，树叶的背面就变成了红色，而叶子的正面仍然是青绿色，这是为什么呢?我在书中找到了答案：这是因为空气渐渐变冷、背面的叶绿素减少、花青素增多的缘故;而正面叶绿素仍很多，所以呀，它才会叶子背面呈红色，正面呈青绿色。

红背桂树叶很神奇，而紫荆花树的叶子也一样神奇!紫荆花树叶的形状很像一个“屁股”。紫荆花树的树叶是一个对称图形，摸上去有点硬。它独特的地方是，紫荆花树的树叶是由很多根主叶脉支撑着叶片，再从主叶脉向两侧分布分枝叶脉的。紫荆花树叶是青色，远远看去，紫荆花树叶的外形就象一个写好的“丫”字。

金色的秋天，那片片树叶有的在风中跳舞;有的就像只只蝴蝶在随风飘荡。

啊!秋天的树叶多么美妙呀!我爱秋天的树叶。

My favourite season is autumn.When autumn comes ,the weather is very cool and there is much wind.Autumn is a harvest season.Farmers are busy getting in crops .They are tired but very happy .

I like autumn.I like playing basketball,football and table tennis.I also like playing tennis.I like playing games with my good friends.I like skipping,too.At weekends ,I skip with my best friend.We have a good time.

Sometimes I climb the hills with my parents.We take a lot of food with us ,such as hamburgers ,eggs ,bread and so on .We also take a camera.with us .We have a picnic on the hill.We also take many pictures.We feel very happy.

Autumn girl walked the silent footsteps, the beautiful autumn to the world.

She waved a magic wand, the green rice fields into a golden. Far from the field, the field like a golden carpet; field, the channel side, a small river, that tree green cypress, is embroidered on the carpet on the green side; ridge, grass, grow all kinds of Colorful flowers, is embedded in the carpet on the color of pearls. The cool autumn wind blowing, blowing on the rice, the rice thrown the golden waves; blowing in the trees, leaves fluttering leisurely fall, like butterflies dancing in the fields. I stand on the ridge, you listen, the wind blowing rice "rustling" sound, between the grass, the insects "tweeted" sound, the branches, the birds "grumble" sound, with our childrens laughter Sound, merged into a ensemble; like a symphony, played the harvest of the movement.

I love autumn, more love the field of autumn. Because she is full of joy, full of hope, full of vitality.

当满城的梧桐树开始变黄时，南京城的秋天就到来了。秋天的每一片树叶都值得人们赞美和收藏，因为它们各有各的姿态。颜色和形状上的不同，为每一片叶子都蒙上了一层面纱。

银杏的叶子在我看来是最美丽的。原本，绿油油的树叶并不突出，奇迹就发生在这美丽的秋天里：碧绿的银杏边上开始泛黄，原本青翠的面儿上变成了黄绿色，一条条发散状的叶脉变成了深褐色了。叶子的形状大小不一，是一片片天然形成的小扇子。如果叶子垂下来，那就是一位美丽的小仙女了!风一吹，她们就舞动着美丽的裙摆，开始跳芭蕾舞剧——《天鹅湖》，真是太美了! 枫树的叶子也很美丽。枫叶原来是青绿色的，之后秋风这位魔法师挥动着魔杖，把它们变成了深红色，就像人在不同的季节换上不同的衣裳一样。秋风还给枫叶们镀上了亮红色的边儿，就像人为自己打上领结、喷上亮粉一样。他还给叶脉涂上了暗红色的水彩、给叶柄穿上了梅红色的长筒牛仔裤，真像人们所说的“女大十八变”一样啊!枫叶的大小都差不多，偶尔有几个小红枫叶藏在其中，都差不多是小手掌的形状。虽然没有几片是轴对称的，但也透露出残缺之美。如果风吹一下，这只小手掌仿佛在和人说“拜拜”呢!小手掌上的花纺分明就是一棵枝繁叶茂的大树!

虽然这两种树叶都很美，但是人们在赞叹地同时又惋惜道：“这树叶的命真短啊!春天就成了烂泥”。我想说：“古人云、秋风不是无情物，化作春泥更护花。我们不要为这时的树叶而难过，因为来年这片树片会化成更多的小树叶，给大树妈妈添彩。所以，树叶是不会死的”。 秋天的树叶真奇妙呀!

评析：这篇文章作者将“树叶”比作“小扇子”、“小手掌”等，生动形象地写出了树叶的形状。同时，作者引用“落红不是无情物，化作春泥更护花”一句，表达了对秋天的树叶的奉献精神的赞美之情。

The wind of autumn is a door. It took it cool and gentle, gently and gently took us into the autumn palace.

The wind of autumn is a little painter. You see, it sprinkled the powder to the dandelion, dandelion really like a parachute, floating Wawa wandering, floated the beauty of autumn. Golden powder is given to the sun flower, the golden petals really like a gold coin. The red is the sorghum, the sorghum put on the red new clothes, in the autumn wind Yaotouhuangnao, shaking non-stop, more than one, how beautiful is it? Like a burning torch!

Autumn wind, hidden very interesting things. Big yan fly south, birds take the new house, as well as chrysanthemum fairy than the United States, leaves the baby to travel, a lot of things are hiding in the wind! Carefully to listen, you will be able to hear.

Autumn wind, blowing a golden assembly number, it tells you, science days to come, the fall to be passed. The turtle indented into the shell, penguin mother weaving a warm bag, the snake is ready to skin ... ... we have to winter.

Autumn of the wind, brought us the joy of autumn, the joy of harvest.

Autumn is a harvest season, the field is full of red, yellow, purple ... ...

Sunday, my mother and I went to the grandmother to go on the road, the road on both sides of a piece of Koelreutus full of golden flowers, like a string of lanterns, the wind swing. The tree was full of red glowing seeds, like a small fan, autumn wind blowing, they are like a bird in the air like dancing.

Into the grandmothers village, a large piece of a large pear, Huang Chengcheng pear covered with branches, like a small gourd, pick one, bite, crisp, sweet, really delicious! Grandmothers home Persimmon in the garden, persimmon tree covered with a heavy persimmon, some of them hanging head, and some head down, the sun a photo, all exposed the orange smile, as if to welcome my arrival.

Persimmon park next to, I was surprised to find that corn how are put on the "yellow robe", dressed like a group of fat dolls, are grinning scrambled toward me laughing. I am happy to run over to jump, sing ... ...

I like the fields of autumn, because it is not only charming, but also to bring people to harvest and joy.

在秋杀万千

天地变色的基调下

我，一枚秋叶

一枚凋落但不变色的叶子

在不停地漂泊，

虽然越过了千山万水

即便还有风霜雨雪

我也决不停止奔跑的步伐

绝不忘记追求春天的理想!

——因为我不甘

也不愿被污泥吞噬。

我不记得何时开始漂泊的

但我知道前路漫漫

还有很多见过的与想不到的考验。

寒雾的封锁

暴风的驱赶

秋日的嘲笑

飞禽的捉弄

还有将来冰雪的萧杀

——但我不怨恨它们，

因为它们身不由己

他们有自己的苦衷，

我可怜它们的无奈

欣喜自己的幸运。

但我从不得意忘形，

虽然我俯视过沧海

虽然我脚踏过高峰

虽然我拥抱过彩虹

虽然我亲近过明月，

——因为我的理想还在前方

所以我不曾也不会苟且停歇。

当夜深人归

风息月黑的时刻

没有一点外在的压力

我却最为脆弱

我慌张得手足无措

我空虚得透明甚至虚无

——我肆无顾虑地投向污泥的怀抱

我想停止奔波

找一个安身之处

颐养天年、悠悠老去。。。。

当我快掉进污泥的刹那，

它那刺鼻的臭味让我惊醒

我似乎看到了自己脸上的污秽

——我奋力一振

再次飞入苍穹，

暴雨骤临

我会心一笑

看着缥缈的星光

逆向奔驰

向着春天的方向!

I like autumn. I love the falling leaves in autumn. They cover the ground with golden yellow.

When you walk on them, they rustle beneath your feet, just as if they are singing to you.

I know trees get ready for their next years rebirth by doing this, so I enjoy them without any sad feelings.

The fields in autumn are fruity. People are easy to have good mood in a harvest season.

So cant autumn sights bring happiness to us as well?

春天的叶子细腻嫩绿，夏天的叶子宽大厚重，冬于的叶子干掉落，但我还是对秋天的叶子情有独钟。

今天，朋友马广瑞给我送来几片“火炬树”树叶，在远处看，颇像一团燃烧的火焰，火炬树的叶子果然名副其实。火炬对夏天是青色的，到了秋天，树叶就变为火红色的了。仔细地看这片叶子长约十厘米左右，宽不到四厘米，边缘有一个个小锐角组成，却不刺手，叶茎还是青绿色的，还仍然十分粗壮，超出叶子的平面。只看叶脉的话，那就像一个小迷你松树。叶子正面十分光滑，但反面却十分粗糙。仔细闻一闻火炬树的味道，虽然不象薄荷一样清香，也不像丁香一样浓郁，但却散发着泥土的芬芳，令人回味。把火炬树叶放在阳光或灯光下，你会看出火炬树叶的红十分鲜艳，美丽动人。看着看着，我仿佛置身于火炬树林中，像被包围在这烈火里，体会到杜牧“停车坐爱枫林晚，霜叶红于二月花”的意境。

我爱秋天的叶子，它默默地为大地输送着阳光、水份。枯落了，为泥土增添了一份肥沃，一份营养。我爱秋天，更爱“化做春泥更护花”的奉献者——叶子。

t is autumn. The sky is clem and cloudless. The summer heat is gone. The autumn wind brings us cool. At once the version comes to my mind, "Autumn is rich with fruit and grain. " Actually I see pomegranates red and round on the stall in the market and the pcars big, yellow and juicy. My mouth waters for them. The grains have been harvested, the rice, wheat and corn.

The laurel trees give off fragrance. The perfume makes its way stralght into my nose. The brlght red canna are standing behind rows of tall plane trees. I am waiting for their leaves to turn yellow.Then l can trample on the fallen leaves on both sides of the ground.

At times the autumn rain keeps falling silandy on the trees and flowers and the ground. It washes everything clean. When the sun comes out, the droplets shine bright on the yellow leaves.

What a beautiful painting! Autumn is the season for harvest no pains, no gains. I must study hard so that I can have a big harvest in all my subjects.

In autumn, some emotions, such as fallen leaves as they decline, some have lingering shadow, only in the virtual network is indistinct in the familiar names. It withered on the decline,ashes are also good, regardleof the feelings of like how the leaves like a tree in full bloom and how to decline. I was standing on the flow of time, laughing, even if the sky flying leaves, eventually covering the lives of desolation.

译文

秋中，有些感情便如落叶般凋零了，有些影子却挥之不去，只在网络虚缈中才有熟悉的名字。凋零就凋零吧，倦缩也好，成灰亦好，管它感情如一树红叶般怎样盛开，怎样凋零。我站在川流不息的时间里，谈笑风生，任凭满天的叶子飞舞，最终覆盖苍凉的生命。

秋天到了，漫山遍野都是黄色的：黄色的草地、黄色的树叶······可是，你们知道吗?走进秋天里，并不都是黄色的，还有绿色的呢!

在秋天里，“金桂香飘十里远”，瞧!那桂花树上开这金黄色的小花，花儿旁边，当然就是桂花树叶了。桂花树叶可不是黄色的，它就是绿色的。

一阵大风刮过，调皮的风儿揪掉了几片叶子，我捡了一片仔细观察，我发现：叶子上，粗的茎脉是程直线状的;细的茎脉，却是程弯曲状的，并组成了一个个小小的、不规则的“圆形”和“长方形”;我拿着它放在鼻子底下，

哇!它竟有淡淡的清香!到了第二天早晨，我发现：桂花树叶的香味没有昨天那么浓了;叶子的底部还有点紫，但它并没有枯萎，也许，它真在与死神斗争着! 第三天早晨，叶子一点香味都没有了，而且叶子的底部还非常紫。我想：也许它“生病“了。但是它仍然没有死去。为什么它的香味会没有了呢?我在思考着。也许是因为，它在想：我就算死了，我也要为别人牺牲我自己，首先，我要把我的香味贡献给空气······ 想到这儿，我便把这一片叶子放在了泥土上，因为，只有这样，它才能为了别人牺牲自己;只有这样，我才能帮它实现“叶生”(叶子的一生)的最后一个梦想······

Why do leaves change color in the fall? asks Patricia Brown, of New York City.

Autumns cool days are trimmed with deep blue skies and golden light, and brilliant leaves of yellow, orange and red. Leaves changing color in the fall are a trees way of preparing for long winter, rather like we put up storm windows and pull warm clothes and blankets out of storage.

In summer, the leaves on trees like pin oaks and sugar maples are green because they are chock-full of the green pigment chlorophyll.

Trees need sunlight to produce chlorophyll. In turn, chlorophyll uses sunlights energy to split water (H2O) into hydrogen and oxygen. Meanwhile, leaves also absorb carbon dioxide gas from the air. The end products of leaf chemistry: carbohydrates (homemade plant food for the tree), and oxygen, released into the air (the gas we need to breathe). The whole process is called photosynthesis.

Along with green chlorophyll, most leaves also contain yellow, orange and red-orange pigments celled carotenoids. Trees dont need light to make carotenoids. Botanists call them "helper pigments," because carotenoids absorb some sunlight and (nicely) pass the energy along to chlorophyll. We dont see much of these deputy pigments (carotene, lycopene, and xanthophyll) in summer, because they are masked by abundant green chlorophyll.

But the ever-shortening days of fall mean less daylight and colder weather. The average tree is rushing to save all the nutrients it can for its winter hibernation. Nitrogen and phosphorus are pulled from leaves for storage in branches. A layer of corky cells grows between the leaves stems and their branches, reducing the leaves supply of nutrients and water.

With diminished sunlight, water, and nutrients, chlorophyll synthesis slows. Old, worn-out chlorophyll breaks down at the usual rate--ironically, sunlight destroys it--so each leafs stock gradually dwindles. And as the green fades, yellow and orange emerge from hiding.

Unlike the green and yellow pigments, red and purple pigments (anthocyanins, part of the flavonoid class) actually form in leaves in the autumn, tinting leaves scarlet and burgundy.

Botanists have long wondered why some trees are genetically programmed to manufacture anthocyanins in the fall. New research indicates that anthocyanins may be a trees own sunscreen.

Anthocyanins are made in a leafs sugary sap, with the help of lots of sun and cool temperatures. Botanists think that anthocyanins shield the leaves fading photosynthesis factories from too much sunlight, rather like the pigment melanin protects our skin from the sun. While the red pigments act as a shield, the tree feverishly breaks down and pulls nutrients out of leaves and into its limbs and trunk before leaves drop or die.

Anthocyanins may also act like Vitamin C or E, scavenging so-called "free radicals" before they can do oxidizing damage to a fall leafs fragile structure.

Upper and outer leaves tend to be reddest, since they are most exposed to sunlight and cold. In some trees, like sugar maples, the reds of the anthocyanins combined with the yellows of the carotenoids make especially brilliant orange leaves.

[经典英语作文：秋天叶子为什么会变颜色