cactus

/ˈkæktəs/

/ˈkæktəs/

Other forms: cacti; cactuses

A cactus is a succulent desert plant that's often covered in sharp spines. Some cacti grow brilliantly colored flowers, but none of them have leaves.

You can grow an indoor cactus in a pot — it's a fairly easy plant to care for, since it prefers to be watered infrequently. Cacti are able to conserve water, which is why they do well in very dry environments, like the American Southwest. The Greek root of cactus is kaktos, the name of a specific spiky Sicilian plant.

Definitions of cactus

1. noun

   any succulent plant of the family Cactaceae native chiefly to arid regions of the New World and usually having spines
   types:

   Acanthocereus pentagonus, Acanthocereus tetragonus, pitahaya, pitahaya cactus, pitaya

   cactus of the southwestern United States and northern Mexico having edible juicy fruit

   Aporocactus flagelliformis, rat's-tail cactus, rattail cactus

   commonly cultivated tropical American cactus having slender creeping stems and very large showy crimson flowers that bloom for several days

   Ariocarpus fissuratus, living rock

   usually unbranched usually spineless cactus covered with warty tubercles and having magenta flowers and white or green fruit; resembles the related mescal; northeastern Mexico and southwestern United States

   Carnegiea gigantea, saguaro, sahuaro

   extremely large treelike cactus of desert regions of southwestern United States having a thick columnar sparsely branched trunk bearing white flowers and edible red pulpy fruit

   night-blooming cereus

   any of several cacti of the genus Cereus

   coryphantha

   a cactus of the genus Coryphantha

   barrel cactus, echinocactus

   any cactus of the genus Echinocactus; strongly ribbed and very spiny; southwestern United States to Brazil

   hedgehog cereus

   cactus of the genus Echinocereus

   rainbow cactus

   a stout cylindrical cactus of the southwest United States and adjacent Mexico

   epiphyllum, orchid cactus

   any cactus of the genus Epiphyllum having flattened jointed irregularly branching stems and showy tubular flowers

   barrel cactus

   a cactus of the genus Ferocactus: unbranched barrel-shaped cactus having deep ribs with numerous spines and usually large funnel-shaped flowers followed by dry fruits

   Easter cactus, Hatiora gaertneri, Schlumbergera gaertneri

   spring-blooming South American cactus with oblong joints and coral-red flowers; sometimes placed in genus Schlumbergera

   night-blooming cereus

   any of several cacti of the genus Hylocereus

   Lemaireocereus chichipe, chichipe

   tall treelike Mexican cactus with edible red fruit

   Lophophora williamsii, mescal, mezcal, peyote

   a small spineless globe-shaped cactus; source of mescal buttons

   mammillaria

   any cactus of the genus Mammillaria

   Mammillaria plumosa, feather ball

   a low tuberculate cactus with white feathery spines; northeastern Mexico

   Myrtillocactus geometrizans, garambulla, garambulla cactus

   arborescent cactus of western Mexico bearing a small oblong edible berrylike fruit

   Knowlton's cactus, Pediocactus knowltonii

   small clustering cactus of southwestern United States; a threatened species

   nopal

   any of several cacti of the genus Nopalea resembling prickly pears

   prickly pear, prickly pear cactus

   cacti having spiny flat joints and oval fruit that is edible in some species; often used as food for stock

   Opuntia cholla, cholla

   arborescent cacti having very spiny cylindrical stem segments; southwestern United States and Mexico

   mistletoe cactus

   a plant of the genus Rhipsalis

   Christmas cactus, Schlumbergera baridgesii, Schlumbergera buckleyi

   epiphytic cactus of Brazilian ancestry widely cultivated as a houseplant having jointed flat segments and usually rose-purple flowers that bloom in winter

   night-blooming cereus

   any of several night-blooming cacti of the genus Selenicereus

   Schlumbergera truncatus, Thanksgiving cactus, Zygocactus truncatus, crab cactus

   South American jointed cactus with usually red flowers; often cultivated as a houseplant; sometimes classified as genus Schlumbergera

   hedgehog cactus

   cactus of the genus Echinocactus having stout sharp spines

   Echinocactus grusonii, golden barrel cactus

   large cactus of east central Mexico having golden to pale yellow flowers and spines

   Opuntia lindheimeri, nopal

   cactus having yellow flowers and purple fruits

   Opuntia tuna, tuna

   tropical American prickly pear of Jamaica

   Selenicereus grandiflorus, queen of the night

   tropical American climbing cactus having triangular branches; often cultivated for its large showy night-blooming flowers followed by yellow red-streaked fruits

   type of:

   succulent

   a plant adapted to arid conditions and characterized by fleshy water-storing tissues that act as water reservoirs