今天我来为大家介绍一下梧桐树。
梧桐树,即“中国梧桐”,是梧桐科梧桐属的植物,别名青桐、桐麻,也属落叶大乔木,一般高达15米;树干挺直,树皮绿色,平滑。原产中国,南北各省都有栽培,也为普通的行道树及庭园绿化观赏树。我们所说的法国梧桐其实是悬铃木中的一种。
梧桐树的叶子极似枫树叶,甚至连脉络都一样。梧桐树的叶子会变色哦!春天的时候,叶子是嫩绿嫩绿的;一到秋天,叶子就会慢慢变黄。这是为什么了呢?原来在夏天时,树叶工作得很努力,可是,天气转凉后,它就停止了工作。树叶所制造的营养也就不能送到树枝和树干上,而沉淀在叶子里。树叶的叶绿素也会遭破坏,就和留在叶子里的养分或枯萎了的茶褐色混合,这样就变成各种美丽的颜色了所有的树叶中都含有绿色的叶绿素,树木利用叶绿素捕获光能并且在叶子中其他物质的帮助下把光能以糖等化学物质的形式存储起来。除叶绿素外,很多树叶中还含有黄色、橙色以及红色等其他一些色素。虽然这些色素不能像叶绿素一样进行光合作用,但是其中有一些能够把捕获的光能传递给叶绿素。在春天和夏天,叶绿素在叶子中的含量比其他色素要丰富得多,所以叶子呈现出叶绿素的绿色,而看不出其他色素的颜色。当秋天到来时,白天缩短而夜晚延长,这使树木开始落叶。在落叶之前,树木不再像春天和夏天寻样制造大量的叶绿素,并且已有的色素,比如叶绿素,也会逐渐分解。这样,随着叶绿素含量的逐渐减少,其他色素的颜色就会在叶面上渐渐显现出来,于是树叶就呈现出黄、红等颜色。
梧桐树的价值也很大哟。梧桐树为栽培于庭园的.观赏树木。木材轻软,为制木匣和乐器的良材。种子炒熟可食用或榨油,油为不干性油。根皮、茎、叶、花、果和种子均可药用,治腹泻、疝气、须发早白,有清热解毒的功效。树皮的纤维洁白,可用以造纸和编绳等。木材刨片可浸出粘液,称刨花,润发。
梧桐子是梧桐树的种子。秋末至冬初采收,除去杂质,晒干。干燥种子,圆球形或类圆形,径6~8mm,黄棕色至深棕色,表面皱缩成网纹状。外层种皮较脆,易破裂,内层种皮坚韧。除去后,内有肥厚的淡黄色胚乳;子叶两片薄而大,紧贴在胚乳上,胚根位于较狭的一端。气、味均微。以个大、饱满、棕色、无杂质者为佳。陶隐居云:“桐树有四种,青桐叶皮青似梧而无子。梧桐色白,叶似青桐而有子,子肥亦可食。”李时珍说:“梧桐处处有之。树似桐而皮青不皵,其木无节直生,理细而性紧。叶似桐而稍小,光滑有尖。其花细蕊,坠下如醭。其荚长三寸许,五片合成,老则裂开如箕,谓之藁鄂。其子缀于藁鄂上,多者五六,少或二三。子大如胡椒,其皮皱。其子,甘平无毒。”
梧桐树就是这样的哟。
Dear Sir,
I am writing to seek your advice regarding which subject I should choose as my major, history or computer science. I am studying in the last year in high school now.
Next year, I hope that I will be able to enroll in your college. I began to take a special interest in history when I was a primary school student. I can still remember the historical stories my teachers told in class, so I was wondering if I should continue to study in your college. However, several days age, one of my friends told me that computer science is more popular nowadays.
As a matter of fact, many jobs need IT skills. I was advised that it’s more important to find a job than merely to satisfy personal interest. Therefore, it is now very hard for me to decide which subject I should choose. Must I give up my favorite subject and take employment need as a priority? I would be more than grateful to you if could tell me your advice about this. Your early reply would be highly appreciated.
Yours faithfully
Wang Rutao
Such is sons’ nature; I really do not know how to express my thanks to you. However, I can imagine, on the day 18 years ago, when you gave birth to me, what a complex feeling you had. In the past few years, every day you struggle me up in the morning and prepare breakfast for me, then in the afternoon, you always welcome your only son with delicious foods after a day‘s hard work. Now your son has been 18 and will go to university soon, like a bird is leaving its parents. Nevertheless, your footprints on my heart will never ever fade and I love you mum!
your son
我有一辆心爱的小自行车,从三年级起我就每天骑着它去上学,它给我带来了许多的乐趣,在它的陪伴下我一天天长大。
记得我8岁生日那天,爸爸给我买了一辆20型黑色的横梁小自行车作为生日礼物。说它是自行车,其实更像玩具。它油亮的小车身,软软的小车座,我只看了一眼就再也舍不得放下它了。
可是,小自行车好像和我很陌生,试骑时总不听我使唤,车把摇来晃去,我骑在车上就像耍杂技。不好,前方有个排球杆,我左摆右摆,只听“砰”的一声,车头撞了上去,看看碰歪的车把,我心里好难受。
有了这次教训,我不敢再轻易独自骑车,而是请爸爸帮我扶着,这样我渐渐地掌握了骑车的要领,小自行车也终于接受了我这个小主人。
每天放学回家,我都要骑着它兜上几圈,从中体味骑车的快感。小自行车给了我展现技能的机会,使我找到了自信心,获得了极大的满足感。
四年级以后,爸爸妈妈开始让我骑车子上学。这时,小自行车的功能开始变化,它已不再只是一件玩物,还有了实用价值。有了小自行车的帮助,我每天可以独自上学、回家,再也不用爸爸妈妈接送了。每当我挎着书包,骑着车,和大人一样穿行在热闹的公路上,心里就有说不出的喜悦。小自行车给了我独立的意识和成熟的感觉。
© 2022 xuexicn.net,All Rights Reserved.