Geological Formation of Mexico—The Tierra Caliente—The Tierra Templada—The Tierra Fria.
The Sylvan1 Wonders of Sikkim—Changes of the Forest on ascending3—The Torrid Zone of Vegetation—The Temperate4 Zone The Coniferous Belt—Limits of Arboreal5 Vegetation—Animal Life.
The prodigious6 height attained7 in the torrid zone, not only by single mountains, but by vast tracts8 of land, and the diminution9 of temperature which is the necessary consequence of their elevation10 above the level of the sea, enable the inhabitants of many tropical countries, without leaving their native land, to view the vegetable forms of every zone, and to pluck nearly every fruit that is found between the equator and the arctic circle. In Asia, Africa, and America, in the islands of the Indian Archipelago, and in the Hawaiian group, where the Mauna Loa towers to the height of Mont Blanc, and girdles his foot with palms, while snow rests for a great part of the year upon his summit, we find numerous examples of a rapid transition from the torrid to the temperate or frigid11 zone, often within the range of a single day’s journey.
It would far exceed my limits were I to attempt to follow all these gradations of climate throughout the wide extent of the tropics; but a short description of the Mexican plateaus, and of the slopes of Sikkim, which I have selected as remarkable12 instances of the wonderful change of vegetation resulting from the progressive elevation of the land, will, I hope, prove not uninteresting to the reader.
After traversing South America and the Isthmus13 of Darien,80 the giant chain of the Andes spreads out, as it enters Mexico, into a vast sheet of table-land, which maintains an elevation of from 6,000 to 9,000 feet for the distance of 200 leagues, until it gradually declines in the higher latitudes14 of the north, or descends15 in successive stages to the sea-board of the Atlantic. To this remarkable geological formation the land, though warmed during a part of the year by the rays of a vertical16 sun, owes that astonishing variety of climate and productions which would make it the envy of the earth, if peopled by a race that knew better how to utilize17 the gifts of Nature.
All along the Mexican Gulf18 stretches a broad zone of lowlands, called the tierra caliente, or hot region, which has the usual high temperature of the tropics. Parched19 and sandy plains, dotted with mimosas and prickly opuntias, are intermingled with savannahs, and woodlands of exuberant21 fertility.
The branches of the stately forest trees are festooned with clustering vines of the dark purple grape, convolvuli, and other flowering parasites22 of the most brilliant dyes. The undergrowth of prickly aloe, matted with wild rose and honeysuckle, makes in many places an almost impervious23 thicket24. In this wilderness25 of sweet-smelling buds and blossoms flutter birds of the parrot tribe, and clouds of butterflies, whose colour, nowhere so gorgeous as here, rival those of the vegetable world; while birds of exquisite27 song,—the scarlet28 cardinal29, and the mocking-bird that comprehends in his own notes the whole music of a forest,—fill the air with melody.
CARDINAL.
MOCKING-BIRD.
But, like the genius of evil, the malaria30 engendered31 by the decomposition32 of rank vegetable substances in the hot and humid soil, poisons these enchanting33 retreats, and from the spring to the autumnal equinox renders them dangerous or fatal to man.
Hastening to escape from its influence, the traveller, after passing some twenty leagues across the dreaded35 region of the yellow-fever, finds himself rising into a purer atmosphere. His81 limbs recover their elasticity36. He breathes more freely, for his senses are not now oppressed by the sultry heats and intoxicating37 perfumes of the lowlands. The aspect of nature, too, has changed, and his eye no longer rests on the gay variety of colours with which the landscape was painted there. The vanilla38, the indigo39, the chocolate-tree disappear as he advances, but the sugar-cane and the glossy-leaved banana still remain; and when he has ascended40 about four thousand feet, he sees, in the unchanging green and the rich foliage41 of the liquidambar-tree, that he has reached the height where clouds and mists settle in their passage from the Mexican Gulf, and keep up a perpetual moisture.
He is now beyond the influence of the deadly vomito on the confines of the tierra templada, or temperate region, where evergreen42 oaks begin to remind him of the forests of central Europe. The features of the scenery become grand, and even terrible. His road sweeps along the base of mighty43 mountains, once gleaming with volcanic44 fires, and still glistening45 in their mantles46 of snow, which serve as beacons48 to the mariner49 for many a league at sea. All along he beholds50 traces of their ancient combustion51 as his road passes over vast tracts of lava52, bristling53 in the fantastic forms into which the fiery54 torrent55 has been thrown by obstacles in its career. Perhaps at the same moment, as he casts his eyes down one of those unfathomable ravines or barrancas, which often, to a depth of more than 1,200 feet, rend34 the mountain-side, he sees its sheltered and sultry recesses56 glowing with the rich vegetation of the tropics: as if these wonderful regions were anxious to exhibit, at one glance, the boundless57 variety of their flora58. Cactuses, euphorbias, and dracænæ, with a multitude of minor59 plants, cling to the rocky walls; while in the depth of the gorge26 stand huge laurels60, fig-trees, and bombaceæ, whose blossoms exhale61 almost overpowering odours, and whose trunks are covered with magnificent creepers, expanding their gay petals62 in the torpid63 air. Still pressing upwards64, he mounts into regions favourable65 to other kinds of cultivation66. He has traced the yellow maize67 growing from the lowest level; but he now first sees fields of wheat and the other European cereals, brought into the country by the Spanish conquerors68, and with these, plantations69 of the American agave, which, among other uses,82 provides the Mexican with his favourite beverage70. The oaks acquire a sturdier growth; and at an elevation of about eight thousand feet, the dark forests of pine announce that he has entered the tierra fria, or cold region,—the third and last of the great natural terraces into which the country is divided.
* * * * *
Loaded with vapours, the prevailing71 southerly sea-winds, after crossing the dead level occupied by the delta72 of the Ganges and Burrampooter, strike against the mountain-spurs of Sikkim, the dampest region of that stupendous chain, and expending73 their moisture on their flanks, clothe them with a thick mantle47 of verdure to an enormous height. The giant peaks of Donkiah, Kinchinghow, and Kinchinginga, the third great mountain of the world (28,178 feet), form the culminating points of this magnificently wooded region, and look down upon the dense74 forests which, varying as they rise, extend between the plains of Bengal and their own perpetual snows.
Dark green woods, of an exclusively tropical character, cover the valleys and declivities to a height of from 4,000 to 5,000 feet. Mighty palms rise above the mass of the forest, while innumerable shrubs75 cover the ground. The prevalent timber is gigantic, and scaled by climbing leguminosæ, bauhinias, and robinias, which sometimes sheathe76 the trunks, or span the forest with huge cables, joining tree to tree. Large bamboos rather crest77 the hills than court the deeper shade, of which there is abundance, for the torrents78 cut a straight and steep course down the hill-flanks. The gulleys which they traverse are choked by vegetation, and bridged by fallen trees, whose trunks are clothed with epiphytical orchids79, pendulous80 lycopodia, ferns, pothos, peppers, vines, bignonias, and similar types of the hottest and dampest climates. The beauty of the drapery of the pothos leaves is pre-eminent, whether for the graceful81 folds of the foliage or for the liveliness of its colour. Of the more conspicuous82 smaller trees the wild banana is the most abundant, its broad crown contrasting with the smaller-leaved plants amongst which it nestles; next comes a screw-pine, with a straight stem and a tuft of leaves, each eight or ten feet long, waving on all sides.
At an elevation of about four thousand feet many plants of the temperate zone, increasing in numbers as the traveller83 ascends83, begin to mingle20 with the tropical vegetation, and to impart new charms to the forest; oaks and walnuts84 are here seen thriving near palms and arborescent ferns; mighty rhododendrons expand over thickets85 of tropical herbage; parasitical86 orchids adorn87 the trunks of the oaks, while thalictrons and geraniums blossom underneath88.
At a height of about 7,000 feet the forest, assuming a decidedly temperate physiognomy, is chiefly composed of oaks, magnolias, chestnuts89, laurels, and walnuts. In many parts arborescent rhododendrons prevail, and ferns are generally very abundant.
About 10,000 feet above the level of the sea begins a zone or belt of coniferæ, chiefly characterised by the silver fir (Abies Webbiana) and the Abies Brunoniana, a beautiful species, forming a stately pyramid, with branches spreading like the cedar90, but not so stiff, and drooping91 gracefully92 on all sides. Only at intervals93 other trees, such as willows94, magnolias, ashes, birches, poplars, apple and cherry trees, appear among the thick pine-woods. The shrubbery and herbaceous plants of this zone are representatives of the whole temperate flora of Europe and America, intermixed with many Chinese, Japanese, and Malayan plants in the richest variety. Several epiphytic orchids grow to an elevation of 10,000 feet, and large spaces are frequently occupied by rhododendrons, which either ascend2 from the temperate zone into the coniferous belt, or first appear in the latter. But very few trees, such as the willows, birches, maples95, and ashes, rise above the coniferous forest, which reaches an upper limit of about 13,000 feet. Most arboreal plants now appear only in a dwarfed96 condition; but the willows still rise in powerful growth over the many Alpine97 shrubs—juniperus, rosa, lonicera, potentilla, rhododendron—which cover the ground; and single specimens98, though low and stunted99, are even found at a height of 16,000 feet.
The whole zone between the extreme limits of arboreal vegetation and the upper boundary of shrubs, generally occupies an elevation of from 13,500 to 16,000 feet, and may justly be called the region of the Alpine rhododendrons: these plants are here by far the most numerous, and frequently belt the mountains with a girdle of richly coloured blossoms, even to the verge100 of the perennial101 snows.
84 A large number of herbs, cruciferæ, compositæ, ranunculaceæ, grasses, sedges, grow and bloom beyond the limits of the shrubs, frequently forming luxuriant pastures, on which numerous herds102 of yacks or grunting-oxen, graze during the summer. Many plants are even exclusively confined to these enormous heights; such as the Rhododendron nivale, the most Alpine of woody plants, which Dr. Hooker found at 17,000 feet elevation, the Delphinium glaciale, and the Arenaria rupifraga, a curious species forming great hemispherical balls, and altogether resembling in habit the curious balsam-bog of the Falkland Islands, which thrives in similar scenes. While on the summits of the Swiss Alps, lichens103 but sparely cover the rocks, wherever they are denuded104 of snow, the wanderer in Sikkim enjoys the sight of many a gay-coloured flower in regions 3,000 or 4,000 feet higher than the summit of Mont Blanc.
MUSK105-DEER.
While thus in Sikkim a wonderful variety of vegetation rises in successive zones from the foot of the mountains to heights unparalleled in any other part of the world, animal life abounds106 only in its lower classes; for the higher orders appear only in few species, and in very scanty107 numbers. On ascending from the foot of the Himalaya, one is astonished at the silence of the woods, broken at intervals only by the voice of a bird, or the chirping108 of a cicada. The solitude109 increases on penetrating110 into the interior of Sikkim, and is but rarely enlivened by a few monkeys in the valleys, some musk deer on the spare grass of the mountains, in heights of from 8,000 to 13,000 feet, or a few larks111, sparrows, finches, pigeons, swallows, falcons112, and other birds, some of which ascend to a surprising height.
The insects, however, and other invertebrata, make up, by their numbers, for the scarcity113 of warm-blooded animals, and are often insupportable plagues to the wanderer. Beautiful butterflies sometimes ascend to heights of 10,000 feet, along with the less agreeable mosquitoes and ticks, and in all the streams up to an elevation of 7,000 feet, hill leeches114 infest115 the waters in such multitudes that bathing is almost impossible.
点击收听单词发音
1 sylvan | |
adj.森林的 | |
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2 ascend | |
vi.渐渐上升,升高;vt.攀登,登上 | |
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3 ascending | |
adj.上升的,向上的 | |
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4 temperate | |
adj.温和的,温带的,自我克制的,不过分的 | |
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5 arboreal | |
adj.树栖的;树的 | |
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6 prodigious | |
adj.惊人的,奇妙的;异常的;巨大的;庞大的 | |
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7 attained | |
(通常经过努力)实现( attain的过去式和过去分词 ); 达到; 获得; 达到(某年龄、水平、状况) | |
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8 tracts | |
大片土地( tract的名词复数 ); 地带; (体内的)道; (尤指宣扬宗教、伦理或政治的)短文 | |
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9 diminution | |
n.减少;变小 | |
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10 elevation | |
n.高度;海拔;高地;上升;提高 | |
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11 frigid | |
adj.寒冷的,凛冽的;冷淡的;拘禁的 | |
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12 remarkable | |
adj.显著的,异常的,非凡的,值得注意的 | |
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13 isthmus | |
n.地峡 | |
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14 latitudes | |
纬度 | |
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15 descends | |
v.下来( descend的第三人称单数 );下去;下降;下斜 | |
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16 vertical | |
adj.垂直的,顶点的,纵向的;n.垂直物,垂直的位置 | |
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17 utilize | |
vt.使用,利用 | |
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18 gulf | |
n.海湾;深渊,鸿沟;分歧,隔阂 | |
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19 parched | |
adj.焦干的;极渴的;v.(使)焦干 | |
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20 mingle | |
vt.使混合,使相混;vi.混合起来;相交往 | |
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21 exuberant | |
adj.充满活力的;(植物)繁茂的 | |
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22 parasites | |
寄生物( parasite的名词复数 ); 靠他人为生的人; 诸虫 | |
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23 impervious | |
adj.不能渗透的,不能穿过的,不易伤害的 | |
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24 thicket | |
n.灌木丛,树林 | |
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25 wilderness | |
n.杳无人烟的一片陆地、水等,荒漠 | |
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26 gorge | |
n.咽喉,胃,暴食,山峡;v.塞饱,狼吞虎咽地吃 | |
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27 exquisite | |
adj.精美的;敏锐的;剧烈的,感觉强烈的 | |
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28 scarlet | |
n.深红色,绯红色,红衣;adj.绯红色的 | |
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29 cardinal | |
n.(天主教的)红衣主教;adj.首要的,基本的 | |
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30 malaria | |
n.疟疾 | |
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31 engendered | |
v.产生(某形势或状况),造成,引起( engender的过去式和过去分词 ) | |
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32 decomposition | |
n. 分解, 腐烂, 崩溃 | |
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33 enchanting | |
a.讨人喜欢的 | |
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34 rend | |
vt.把…撕开,割裂;把…揪下来,强行夺取 | |
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35 dreaded | |
adj.令人畏惧的;害怕的v.害怕,恐惧,担心( dread的过去式和过去分词) | |
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36 elasticity | |
n.弹性,伸缩力 | |
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37 intoxicating | |
a. 醉人的,使人兴奋的 | |
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38 vanilla | |
n.香子兰,香草 | |
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39 indigo | |
n.靛青,靛蓝 | |
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40 ascended | |
v.上升,攀登( ascend的过去式和过去分词 ) | |
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41 foliage | |
n.叶子,树叶,簇叶 | |
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42 evergreen | |
n.常青树;adj.四季常青的 | |
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43 mighty | |
adj.强有力的;巨大的 | |
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44 volcanic | |
adj.火山的;象火山的;由火山引起的 | |
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45 glistening | |
adj.闪耀的,反光的v.湿物闪耀,闪亮( glisten的现在分词 ) | |
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46 mantles | |
vt.&vi.覆盖(mantle的第三人称单数形式) | |
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47 mantle | |
n.斗篷,覆罩之物,罩子;v.罩住,覆盖,脸红 | |
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48 beacons | |
灯塔( beacon的名词复数 ); 烽火; 指路明灯; 无线电台或发射台 | |
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49 mariner | |
n.水手号不载人航天探测器,海员,航海者 | |
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50 beholds | |
v.看,注视( behold的第三人称单数 );瞧;看呀;(叙述中用于引出某人意外的出现)哎哟 | |
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51 combustion | |
n.燃烧;氧化;骚动 | |
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52 lava | |
n.熔岩,火山岩 | |
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53 bristling | |
a.竖立的 | |
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54 fiery | |
adj.燃烧着的,火红的;暴躁的;激烈的 | |
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55 torrent | |
n.激流,洪流;爆发,(话语等的)连发 | |
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56 recesses | |
n.壁凹( recess的名词复数 );(工作或业务活动的)中止或暂停期间;学校的课间休息;某物内部的凹形空间v.把某物放在墙壁的凹处( recess的第三人称单数 );将(墙)做成凹形,在(墙)上做壁龛;休息,休会,休庭 | |
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57 boundless | |
adj.无限的;无边无际的;巨大的 | |
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58 flora | |
n.(某一地区的)植物群 | |
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59 minor | |
adj.较小(少)的,较次要的;n.辅修学科;vi.辅修 | |
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60 laurels | |
n.桂冠,荣誉 | |
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61 exhale | |
v.呼气,散出,吐出,蒸发 | |
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62 petals | |
n.花瓣( petal的名词复数 ) | |
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63 torpid | |
adj.麻痹的,麻木的,迟钝的 | |
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64 upwards | |
adv.向上,在更高处...以上 | |
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65 favourable | |
adj.赞成的,称赞的,有利的,良好的,顺利的 | |
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66 cultivation | |
n.耕作,培养,栽培(法),养成 | |
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67 maize | |
n.玉米 | |
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68 conquerors | |
征服者,占领者( conqueror的名词复数 ) | |
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69 plantations | |
n.种植园,大农场( plantation的名词复数 ) | |
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70 beverage | |
n.(水,酒等之外的)饮料 | |
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71 prevailing | |
adj.盛行的;占优势的;主要的 | |
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72 delta | |
n.(流的)角洲 | |
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73 expending | |
v.花费( expend的现在分词 );使用(钱等)做某事;用光;耗尽 | |
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74 dense | |
a.密集的,稠密的,浓密的;密度大的 | |
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75 shrubs | |
灌木( shrub的名词复数 ) | |
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76 sheathe | |
v.(将刀剑)插入鞘;包,覆盖 | |
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77 crest | |
n.顶点;饰章;羽冠;vt.达到顶点;vi.形成浪尖 | |
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78 torrents | |
n.倾注;奔流( torrent的名词复数 );急流;爆发;连续不断 | |
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79 orchids | |
n.兰花( orchid的名词复数 ) | |
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80 pendulous | |
adj.下垂的;摆动的 | |
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81 graceful | |
adj.优美的,优雅的;得体的 | |
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82 conspicuous | |
adj.明眼的,惹人注目的;炫耀的,摆阔气的 | |
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83 ascends | |
v.上升,攀登( ascend的第三人称单数 ) | |
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84 walnuts | |
胡桃(树)( walnut的名词复数 ); 胡桃木 | |
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85 thickets | |
n.灌木丛( thicket的名词复数 );丛状物 | |
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86 parasitical | |
adj. 寄生的(符加的) | |
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87 adorn | |
vt.使美化,装饰 | |
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88 underneath | |
adj.在...下面,在...底下;adv.在下面 | |
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89 chestnuts | |
n.栗子( chestnut的名词复数 );栗色;栗树;栗色马 | |
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90 cedar | |
n.雪松,香柏(木) | |
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91 drooping | |
adj. 下垂的,无力的 动词droop的现在分词 | |
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92 gracefully | |
ad.大大方方地;优美地 | |
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93 intervals | |
n.[军事]间隔( interval的名词复数 );间隔时间;[数学]区间;(戏剧、电影或音乐会的)幕间休息 | |
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94 willows | |
n.柳树( willow的名词复数 );柳木 | |
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95 maples | |
槭树,枫树( maple的名词复数 ); 槭木 | |
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96 dwarfed | |
vt.(使)显得矮小(dwarf的过去式与过去分词形式) | |
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97 alpine | |
adj.高山的;n.高山植物 | |
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98 specimens | |
n.样品( specimen的名词复数 );范例;(化验的)抽样;某种类型的人 | |
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99 stunted | |
adj.矮小的;发育迟缓的 | |
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100 verge | |
n.边,边缘;v.接近,濒临 | |
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101 perennial | |
adj.终年的;长久的 | |
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102 herds | |
兽群( herd的名词复数 ); 牧群; 人群; 群众 | |
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103 lichens | |
n.地衣( lichen的名词复数 ) | |
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104 denuded | |
adj.[医]变光的,裸露的v.使赤裸( denude的过去式和过去分词 );剥光覆盖物 | |
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105 musk | |
n.麝香, 能发出麝香的各种各样的植物,香猫 | |
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106 abounds | |
v.大量存在,充满,富于( abound的第三人称单数 ) | |
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107 scanty | |
adj.缺乏的,仅有的,节省的,狭小的,不够的 | |
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108 chirping | |
鸟叫,虫鸣( chirp的现在分词 ) | |
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109 solitude | |
n. 孤独; 独居,荒僻之地,幽静的地方 | |
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110 penetrating | |
adj.(声音)响亮的,尖锐的adj.(气味)刺激的adj.(思想)敏锐的,有洞察力的 | |
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111 larks | |
n.百灵科鸟(尤指云雀)( lark的名词复数 );一大早就起床;鸡鸣即起;(因太费力而不想干时说)算了v.百灵科鸟(尤指云雀)( lark的第三人称单数 );一大早就起床;鸡鸣即起;(因太费力而不想干时说)算了 | |
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112 falcons | |
n.猎鹰( falcon的名词复数 ) | |
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113 scarcity | |
n.缺乏,不足,萧条 | |
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114 leeches | |
n.水蛭( leech的名词复数 );蚂蟥;榨取他人脂膏者;医生 | |
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115 infest | |
v.大批出没于;侵扰;寄生于 | |
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