This arum, for example, grows first from a small hard seed with a single lobe14 or seed-leaf. In the seed there is a little store of starch15 and albumen laid up by the mother-plant, on which the young arum feeds, just as truly as the growing chick feeds on the white which surrounds its native yolk16, or as you and I feed on the similar starches17 and albumens laid by for the use of the young plant in the grain of wheat, or for the young fowl18 in the egg. Full-grown plants live by taking in food-stuffs from the air under the influence of sunlight: but a young seedling19 can no more feed itself than a human baby can; and so food is stored up for it beforehand by the parent stock. As the kernel20 swells21 with heat and moisture, its starches and albumens get oxidised and produce the motions and rearrangements of particles that result in the growth of a new plant. First a little head rises towards the sunlight and a little root pushes downward towards the moist soil beneath. The business of the root is to collect water for the circulating medium—the sap or blood of the plant—as well as a few mineral matters required for its stem and cells; but the business of the head is to spread out into leaves, which are the real mouths and stomachs of the compound organism. For we must never forget that all plants mainly grow, not, as most people suppose, from the earth, but from the air. They are for the most part mere22 masses of carbon-compounds, and the carbon in them comes from the carbonic acid diffused23 through the atmosphere around, and is separated by the sunlight acting24 in the leaves. There it mixes with small quantities of hydrogen and nitrogen brought by the roots from soil and water; and the starches or other bodies thus formed are then conveyed by the sap to the places where they will be required in the economy of the plant system. That is the all-important fact in vegetable physiology25, just as the digestion26 and assimilation of food and the circulation of the blood are in our own bodies.
The arum, like the grain of wheat, has only a single seed-leaf; whereas the pea, as we all know, has two. This is the most fundamental difference among flowering plants, as it points back to an early and deep-seated mode of growth, about which they must have split off from one another millions of years ago. All the one-lobed plants grow with stems like grasses or bamboos, formed by single leaves enclosing another; all the double-lobed plants grow with stems like an oak, formed of concentric layers from within outward. As soon as the arum, with its sprouting27 head, has raised its first leaves far enough above the ground to reach the sunlight, it begins to form fresh starches and new leaves for itself, and ceases to be dependent upon the store laid up in its buried lobe. Most seeds accordingly contain just enough material to support the young seedling till it is in a position to shift for itself; and this, of course, varies greatly with the habits and manners of the particular species. Some plants, too, such as the potato, find their seeds insufficient28 to keep up the race by themselves, and so lay by abundant starches in underground branches or tubers, for the use of new shoots; and these rich starch receptacles we ourselves generally utilise as food-stuffs, to the manifest detriment29 of the young potato-plants, for whose benefit they were originally intended. Well, the arum has no such valuable reserve as that; it is early cast upon its own resources, and so it shifts for itself with resolution. Its big, glossy leaves grow apace, and soon fill out, not only with green chlorophyll, but also with a sharp and pungent30 essence which makes them burn the mouth like cayenne pepper. This acrid31 juice has been acquired by the plant as a defence against its enemies. Some early ancestor of the arums must have been liable to constant attacks from rabbits, goats, or other herbivorous animals, and it has adopted this means of repelling33 their advances. In other words, those arums which were most palatable34 to the rabbits got eaten up and destroyed, while those which were nastiest survived, and handed down their pungency35 to future generations. Just in the same way nettles36 have acquired their sting and thistles their prickles, which efficiently37 protect them against all herbivores except the patient, hungry donkey, who gratefully accepts them as a sort of sauce piquante to the succulent stems.
And now the arum begins its great preparations for the act of flowering. Everybody knows the general shape of the arum blossom—if not in our own purple cuckoo-pint, at least in the big white '?thiopian lilies' which form such frequent ornaments38 of cottage windows. Clearly, this is a flower which the plant cannot produce without laying up a good stock of material beforehand. So it sets to work accumulating starch in its root. This starch it manufactures in its leaves, and then buries deep underground in a tuber, by means of the sap, so as to secure it from the attacks of rodents39, who too frequently appropriate to themselves the food intended by plants for other purposes. If you examine the tuber before the arum has blossomed, you will find it large and solid; but if you dig it up in the autumn after the seeds have ripened41, you will see that it is flaccid and drained; all its starches and other contents have gone to make up the flower, the fruit, and the stalk which bore them. But the tuber has a further protection against enemies besides its deep underground position. It contains an acrid juice like that of the leaves, which sufficiently42 guards it against four-footed depredators. Man, however, that most persistent43 of persecutors, has found out a way to separate the juice from the starch; and in St. Helena the big white arum is cultivated as a food-plant, and yields the meal in common use among the inhabitants.
When the arum has laid by enough starch to make a flower it begins to send up a tall stalk, on the top of which grows the curious hooded44 blossom known to be one of the earliest forms still surviving upon earth. But now its object is to attract, not to repel32, the animal world; for it is an insect-fertilised flower, and it requires the aid of small flies to carry the pollen45 from blossom to blossom. For this purpose it has a purple sheath around its head of flowers and a tall spike46 on which they are arranged in two clusters, the male blossoms above and the female below. This spike is bright yellow in the cultivated species. The fertilisation is one of the most interesting episodes in all nature, but it would take too long to describe here in full. The flies go from one arum to another, attracted by the colour, in search of pollen; and the pistils, or female flowers, ripen40 first. Then the pollen falls from the stamens or male flowers on the bodies of the flies, and dusts them all over with yellow powder. The insects, when once they have entered, are imprisoned47 until the pollen is ready to drop, by means of several little hairs, pointing downwards48, and preventing their exit on the principle of an eel-trap or lobster-pot. But as soon as the pollen is discharged the hairs wither49 away, and then the flies are free to visit a second arum. Here they carry the fertilising dust with which they are covered to the ripe pistils, and so enable them to set their seed; but, instead of getting away again as soon as they have eaten their fill, they are once more imprisoned by the lobster-pot hairs, and dusted with a second dose of pollen, which they carry away in turn to a third blossom.
As soon as the pistils have been impregnated, the fruits begin to set. Here they are, on their tall spike, whose enclosing sheath has now withered50 away, while the top is at this moment slowly dwindling51, so that only the cluster of berries at its base will finally remain. The berries will swell7 and grow soft, till in autumn they become a beautiful scarlet52 cluster of living coral. Then once more their object will be to attract the animal world, this time in the shape of field-mice, squirrels, and small birds; but with a more treacherous53 intent. For though the berries are beautiful and palatable enough they are deadly poison. The robins54 or small rodents which eat them, attracted by their bright colours and pleasant taste, not only aid in dispersing55 them, but also die after swallowing them, and become huge manure56 heaps for the growth of the young plant. So the whole cycle of arum existence begins afresh, and there is hardly a plant in the field around me which has not a history as strange as this one.
点击收听单词发音
1 hanger | |
n.吊架,吊轴承;挂钩 | |
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2 glossy | |
adj.平滑的;有光泽的 | |
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3 foliage | |
n.叶子,树叶,簇叶 | |
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4 poetical | |
adj.似诗人的;诗一般的;韵文的;富有诗意的 | |
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5 quaint | |
adj.古雅的,离奇有趣的,奇怪的 | |
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6 swelling | |
n.肿胀 | |
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7 swell | |
vi.膨胀,肿胀;增长,增强 | |
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8 hue | |
n.色度;色调;样子 | |
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9 conspicuous | |
adj.明眼的,惹人注目的;炫耀的,摆阔气的 | |
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10 botanist | |
n.植物学家 | |
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11 dreary | |
adj.令人沮丧的,沉闷的,单调乏味的 | |
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12 terminology | |
n.术语;专有名词 | |
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13 immortality | |
n.不死,不朽 | |
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14 lobe | |
n.耳垂,(肺,肝等的)叶 | |
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15 starch | |
n.淀粉;vt.给...上浆 | |
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16 yolk | |
n.蛋黄,卵黄 | |
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17 starches | |
n.淀粉( starch的名词复数 );含淀粉的食物;浆粉v.把(衣服、床单等)浆一浆( starch的第三人称单数 ) | |
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18 fowl | |
n.家禽,鸡,禽肉 | |
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19 seedling | |
n.秧苗,树苗 | |
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20 kernel | |
n.(果实的)核,仁;(问题)的中心,核心 | |
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21 swells | |
增强( swell的第三人称单数 ); 肿胀; (使)凸出; 充满(激情) | |
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22 mere | |
adj.纯粹的;仅仅,只不过 | |
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23 diffused | |
散布的,普及的,扩散的 | |
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24 acting | |
n.演戏,行为,假装;adj.代理的,临时的,演出用的 | |
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25 physiology | |
n.生理学,生理机能 | |
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26 digestion | |
n.消化,吸收 | |
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27 sprouting | |
v.发芽( sprout的现在分词 );抽芽;出现;(使)涌现出 | |
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28 insufficient | |
adj.(for,of)不足的,不够的 | |
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29 detriment | |
n.损害;损害物,造成损害的根源 | |
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30 pungent | |
adj.(气味、味道)刺激性的,辛辣的;尖锐的 | |
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31 acrid | |
adj.辛辣的,尖刻的,刻薄的 | |
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32 repel | |
v.击退,抵制,拒绝,排斥 | |
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33 repelling | |
v.击退( repel的现在分词 );使厌恶;排斥;推开 | |
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34 palatable | |
adj.可口的,美味的;惬意的 | |
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35 pungency | |
n.(气味等的)刺激性;辣;(言语等的)辛辣;尖刻 | |
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36 nettles | |
n.荨麻( nettle的名词复数 ) | |
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37 efficiently | |
adv.高效率地,有能力地 | |
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38 ornaments | |
n.装饰( ornament的名词复数 );点缀;装饰品;首饰v.装饰,点缀,美化( ornament的第三人称单数 ) | |
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39 rodents | |
n.啮齿目动物( rodent的名词复数 ) | |
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40 ripen | |
vt.使成熟;vi.成熟 | |
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41 ripened | |
v.成熟,使熟( ripen的过去式和过去分词 ) | |
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42 sufficiently | |
adv.足够地,充分地 | |
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43 persistent | |
adj.坚持不懈的,执意的;持续的 | |
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44 hooded | |
adj.戴头巾的;有罩盖的;颈部因肋骨运动而膨胀的 | |
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45 pollen | |
n.[植]花粉 | |
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46 spike | |
n.长钉,钉鞋;v.以大钉钉牢,使...失效 | |
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47 imprisoned | |
下狱,监禁( imprison的过去式和过去分词 ) | |
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48 downwards | |
adj./adv.向下的(地),下行的(地) | |
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49 wither | |
vt.使凋谢,使衰退,(用眼神气势等)使畏缩;vi.枯萎,衰退,消亡 | |
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50 withered | |
adj. 枯萎的,干瘪的,(人身体的部分器官)因病萎缩的或未发育良好的 动词wither的过去式和过去分词形式 | |
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51 dwindling | |
adj.逐渐减少的v.逐渐变少或变小( dwindle的现在分词 ) | |
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52 scarlet | |
n.深红色,绯红色,红衣;adj.绯红色的 | |
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53 treacherous | |
adj.不可靠的,有暗藏的危险的;adj.背叛的,背信弃义的 | |
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54 robins | |
n.知更鸟,鸫( robin的名词复数 );(签名者不分先后,以避免受责的)圆形签名抗议书(或请愿书) | |
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55 dispersing | |
adj. 分散的 动词disperse的现在分词形式 | |
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56 manure | |
n.粪,肥,肥粒;vt.施肥 | |
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