你好！
仙人掌
cactus 英[ˈkæktəs] 美[ˈkækt<日夏养花网1;s]
n. 仙人掌;
[例句]Researchers observed one bird impale a rodent on a cactus
研究人员观察到一只鸟把一只啮齿动物钉在一棵仙人掌上。

LGF
BVVC

cactus
cereus
cacti
都行

spine指动植物身上的刺
仙人掌的刺：cactus spines
thorn特指植物茎上的刺，亦指带刺的灌木或荆棘，如玫瑰
而仙人掌的刺其实是叶子的退化而非http://www.rixia.cc真正意义上的“刺”，故spine比较合理
sting特指动物（特别是昆虫）的蜇刺
prick动词为刺穿，名词为刺痛

sting这就指的就是植物的刺

是prick

Cactus（ 仙人掌）thorns刺

是thorn。

这是一段维基百科全书对仙人掌的英文介绍，或许能帮上忙

Cactus is the name given to any member of the flowering plant family Cactaceae. Cacti are almost exclusively New World plants. This means that they are native only in North America, South America, and the West Indies. There is however one exception, Rhipsalis baccifera; this species has a pantropical distribution, occurring in the Old World in tropical Africa, Madagascar and Sri Lanka as well as in tropical America. This plant is thought to be a relatively recent colonist in the Old World (within the last few thousand years), probably carried as seeds in the digestive tracts of migratory birds. Many other cacti have become naturalized to similar environments in other parts of the world after being introduced by people.

希望能帮上忙~~~

大英百科全书上查到的,很好用的在线免费词典
http://www.encyclopedia.com/html/c/cactus.asp

CACTUS [cactus]
any plant of the family Cactaceae, a large group of succulents found almost entirely in the New World. A cactus plant is conspicuous for its fleshy green stem, which performs the functions of leaves (commonly insignificant or absent), and for the spines (not always present) of various colors, shapes, and arrangements. Cactus flowers are notably delicate in appearance although usually large and showy; they are commonly yellow, white, or shades of red and purple. Many species are pollinated by bats. Cactus fruits are berries and are usually edible. A cactus plant appears on the coat of arms of Mexico, and the blossom of the giant cactus, or saguaro ( Cereus giganteus ), is the state flower of Arizona.

The plants vary from small, round globes to epiphytes, vines, and large treelike forms. The reduced leaf surface, the enlarged fleshy stem, which is well fitted to store water and to retain it, and the ramified and extensive root system (much reduced in cultivated cacti) make the plant particularly adapted to regions of high temperature and long dry periods. Cacti are not restricted to desert regions, however, for in America they range from the tropics into Canada.

Most cacti bloom in the spring for a very short period, sometimes for only a few hours. The blossoms are noticeably sensitive to light, and often different species blossom only at specific times of the day. One of the most famous of the cacti is the night-blooming cereus usually classified as Selenicereus or C. grandiflora (several other night-blooming cactus species bear the same common name). Its fragrant blossoms unfold at a visible rate after sunset and last only a single night. In many of its native habitats the flowering of this cactus is celebrated with festivals.

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仙人掌的说法是cactus它的复数是cacti，而cereus只是仙人掌的一种，并不是仙人掌的总称，仙人掌有很多种，比如世界上最大的仙人掌Pachycereus pringlei和世界上最小的仙人掌Blossfeldia liliputiana。一下一段是对仙人掌的简单介绍，自己看吧。
A cactus (plural: cacti, cactuses, or cactus) is any member of the succulent plant family Cactaceae, native to the Americas. They are often used as ornamental plants, but some are also crop plants.

Cacti are distinctive and unusual plants, which are adapted to extremely arid and hot environments, showing a wide range of anatomical and physiological features which conserve water. Their stem日夏养花网s have expawww.rixia.ccnded into green succulent structures containing the chlorophyll necessary for life and growth, while the leaves have become the spines for which cacti are so well known.

Cacti come in a wide range of shapes and sizes. The tallest is Pachycereus pringlei, with a maximum recorded height of 19.2 m,[1] and the smallest is Blossfeldia liliputiana, only about 1 cm diameter at maturity.[2] Cactus flowers are large, and like the spines and branches arise from areoles. Many cactus species are night blooming, as they are pollinated by nocturnal insects or small animals, principally moths and bats. Cacti's sizes range from small and round to pole-like and tall.

仙人掌 cactus

sapoten 仙人掌
Arumaj日夏养花网iro 仙人掌
sahuaro 树形仙人掌

Christmas cactus 蟹爪，圣诞仙人掌
nightblooming cereus 月光掌，夜花仙人掌

仙人掌可以在荒沙中成活并且繁衍生长。
Cactus can survive, and multiply in desolate deserts.

Cactus grows in sand. 仙人掌在沙地中生长。

仙人掌
cacti cactus cereus

这三个都有植物仙人掌的意思

cacti
n.
[植]仙人掌

cactus
n.
[植]仙人掌

cereus
n.
[植]仙人掌

哪个都可以哦。。。。