登陆注册
15677900000063

第63章 SHOWY, GAY, or SPRING ORCHIS(25)

After the orchids, no flowers show greater executive ability, none have adopted more ingenious methods of compelling insects to work for them than the milkweeds.Wonderfully have they perfected their mechanism in every part until no member of the family even attempts to fertilize itself; hence their triumphal, vigorous march around the earth, the tribe numbering over nineteen hundred species located chiefly in those tropical and warm, temperate regions that teem with insect life.

Commonest of all with us is this rank weed, which possesses the dignity of a rubber plant.Much more attractive to human eyes, at least, than the dull, pale, brownish-pink umbels of flowers are its exquisite silky seed-tufts.But not so with insects.Knowing that the slightly fragrant blossoms are rich in nectar, bees, wasps, flies, beetles, and butterflies come to feast.Now, the visitor finding his alighting place slippery, his feet claw about in all directions to secure a hold, just as it was planned they should for in his struggles some of his feet must get caught in the fine little clefts at the base of the flower.His efforts to extricate his foot only draw it into a slot at the end of which lies a little dark-brown body.In a newly opened flower five of these little bodies may be seen between the horns of the crown, at equal distances around it.This tiny brown excrescence is hard and horny, with a notch in its face.It is continuous with and forms the end of the slot in which the visitor's foot is caught.

Into this he must draw his foot or claw, and finding it rather tightly held, must give a vigorous jerk to get it free.Attached to either side of the little horny piece is a flattened yellow pollen-mass, and so away he flies with a pair of these pollinia, that look like tiny saddle-bags, dangling from his feet.One might think that such rough handling as many insects must submit to from flowers would discourage them from making any more visits; but the desire for food is a mighty passion.While the insect is flying off to another blossom, the stalk to which the saddlebags are attached twists until it brings them together, that, when his feet get caught in other slots, they may be in the position to get broken off in his struggles for freedom precisely where they will fertilize the stigmatic chambers.Now the visitor flies away with the stalks alone sticking to his claws.

Bumblebees and hive-bees have been caught with a dozen pollen-masses dangling from a single foot.Outrageous imposition!

Does this wonderful mechanism always work to perfection? Alas!

no.It is a common thing to find dead hive-bees and flies hanging from the flowers.While still struggling to escape, the unhappy victims will be attacked by ants, beetles, and spiders, or killed by heavy showers.Larger and stronger insects than honeybees are required to regularly effect pollination and free themselves, especially when they are so unfortunate as to catch several feet in the grooves.Doubtless it is the bumblebee that can transfer pollen with impunity; but very many other insects, not perfectly adapted to the flowers, occasionally benefit them.Among the large butterflies the Papilios, which suck with their wings in motion, are the most useful, because in using their legs to offset the motion of their wings they rapidly repeat those movements which are necessary to draw the pollinia from the anther cells and insert them in the stigmatic chambers of other flowers."Large butterflies like Danais," says Professor Robertson, "hold their wings still in sucking, spending more time on an umbel, but generally carrying pollinia.Small butterflies are worse than useless.They remain long on the umbels sucking, but resting their feet superficially on the flowers.

Since several moths were found entrapped, pollination must often be brought about by night-flying Lepidoptera.As a rule, Diptera (flies) either do not transfer pollinia at all, or become hopelessly entangled when they do."Occasionally pollen-masses are found on the tongues of insects, especially on those of bees and wasps, which move about with their unruly member sticking out.Probably no one has ever made the exhaustive and absorbingly interesting study of the milkweeds that Professor Robertson has.

Better than any written description of the milkweed blossom's mechanism is a simple experiment.If you have neither time nor patience to sit in the hot sun, magnifying glass in hand, and watch for an unwary insect to get caught, take an ordinary housefly, and hold it by the wings so that it may claw at one of the newly opened flowers from which no pollinia have been removed.It tries frantically to hold on, and with a little direction it may be led to catch its claws in the slots of the flower.Now pull it gently away, and you will find a pair of saddlebags slung over his foot by a slender curved stalk.If you are rarely skilful, you may induce your fly to withdraw the pollinia from all five slots on as many of his feet.And they are not to be thrown or scraped off, let the fly try as hard as he pleases.You may now invite the fly to take a walk on another flower in which he will probably leave one or more pollinia in its stigmatic cavities.

同类推荐
  • 太清导引养生经

    太清导引养生经

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。
  • 濒湖炮炙法

    濒湖炮炙法

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。
  • 江南余载

    江南余载

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。
  • 煮粥条议

    煮粥条议

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。
  • 医话

    医话

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。
热门推荐
  • 见色起意

    见色起意

    在正式见面之前,江瑟瑟亲切致电了素未谋面的未婚夫,她想表明立场,这婚,绝壁不结!可是话还没有说出口,手机就被抢了。见了面之后——瑟瑟腼腆地笑了笑:“我们什么时候结婚?”感谢小偷,她未婚夫帅得她合不拢腿!这个男人绝对不能给别人!--情节虚构,请勿模仿
  • 指染成瘾,权少的追妻游戏

    指染成瘾,权少的追妻游戏

    第一次见面,她是小白兔,他是大灰狼,他步步紧逼,将她拆分入腹。小白兔在大灰狼的压迫下终于学会反抗,学会逃跑。她跑,他追,追上,压倒,直到她跑不动为止。错过多年后,再重逢。小白兔已经成长为小狐狸,聪明狡诈,步步为营。大灰狼却退化了锋利的爪牙,看似憨厚纯良,实则本性难移。他依旧在追,她依旧在躲。终于某日,他忍无可忍,恢复本色,韩初雪,再跑,老子把你锁床上!
  • 空楼琴诗

    空楼琴诗

    一个16岁少女经历了宫中的种种残斗,历练成了一个“霸王”。
  • 东方球神

    东方球神

    “我不如他。”勒布朗詹姆斯“我愿意成为他的球队中的角色球员。”科比布莱恩特。“我可不能保证有他在我会拿到2个三连冠。”迈克尔乔丹。“他”——林宇蒙
  • 白色眷恋

    白色眷恋

    因为不满皇马6比2的比分,中国青年律师沈星怒砸啤酒瓶,结果电光火石间,他穿越成了佛罗伦蒂诺的儿子,且看来自09年的小伙子如何玩转03年的欧洲足坛
  • 英雄联盟之斗神

    英雄联盟之斗神

    顶级王者主播再起风云。花式抢人头,稳健补刀,完美战术的配合,巅峰个人技巧,秒级以下的反应手速。新人主播在不断地成长中,向着这个世界号称封神的那些顶尖选手们逐一发起挑战。斗神之战尽在此中。本故事纯属虚构,如有雷同,纯属巧合。(求推荐,收藏)
  • 就是那么任性

    就是那么任性

    “小爷就这么拽!”“呵,本小姐怕你不成?走着瞧!”
  • 窈窕淑女,君子好逑

    窈窕淑女,君子好逑

    瑜翼高中淑女校花楚窈窕在一次意外车祸中穿越回到唐朝。一见钟情于言府大少言君矣,从此展开她反方向进行时的“追爱大作战”。可当拜堂之际眼眸一暗又回到了现代。去瑜翼报道时,遇见了许多熟悉的人,还有人群中那个淡漠的校草,唉呀妈呀,是他!
  • 干哥上阵:独宠我家小娇妻

    干哥上阵:独宠我家小娇妻

    他是她在网上认的干哥,不曾想却在某天遇到。他爱上了她,他帮她逆袭,让她做了市老大。“哥,你干嘛?”她把被子盖到自己身上,一脸不可置信。“睡觉。”他理所当然。“你自己有房间。”她沉下脸。“没你。”“那你为什么要脱裤子?”“你TM睡觉穿裤子?”喜欢的话记得收藏加书评哦,不然会打击我码字的心噢~进来看看吧
  • 错过,在,也不见

    错过,在,也不见

    关于高中时的爱恨情仇,以第一人称写的青春小说