Cacteae is a tribe of plants belonging to the family Cactaceae

Cactus

A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...

. They consist of species that either have no leaves

Leaves

-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...

 at all, or have stems that resemble leaves. Some have scales that resemble leaves, but the majority have leaf-bases that have been fused either into ribs or tubercles.

The Cacteae tribe is very large, comprising almost 75% of all the Cactaceae. As a result it has been sub-divided into eight sub-tribes, these being as follows: Cactanae, Cactinae, Cereinae, Echinocactinae, Echinocereinae, Epiphyllinae, Hylocereinae, and Rhipsalidinae. Members of this tribe have been moved around and often placed in other tribes.

Cactanae

Similar to Echinocactinae, these plants tend to have either globular or stumpy cylindrical main stems. They don't branch, but may produce offshoots from the base. They have ribs that are fused together tubercles, so much so that there is only a vague bump where the areoles are. The plants also develop a pronounced, wooly, and occasionally bristly cephalium from which the flowers appear. There are only two genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 comprising this subtribe, Disocactus and Melocactus.

Cactinae

This is quite an important subtribe, especially to cacti-lovers, as it contains the large Mamillaria genus. This may not be as large as the Opuntia genus but it contains more than its fair share of hybrids and variations - sometimes making it near impossible to determine the species of some plants. They all produce globular (turning cylindrical) stems and most produce offshoots freely. The tubercles are generally arranged in spirals. The principal genera of this subtribe are Coryphantha, and Mamillaria and sometimes taking 30-years for just one branch to form

Cereinae

Most of these plants grow erect, though a few are more horizontal. They generally have a thick, columnar, main stem from which branches eventually grow. These branches eventually also grow branches leading to a tree-like shape in very old specimens. They almost always have pronounced ribs with areoles that normally have many spines. The principal genera are Cephalocereus, Cereus, Cleistocactus, Espostoa, and Oreocereus.

Echinocactinae

This sub-tribe is composed of species with globular (or stumpy cylindrical) stems which may have branches, but always have pronounced ribs that develop over time by the fusing of the tubercles (which are initially separate). The plants can grow to quite a large size overall. Member genera are amongst the strangest, slowest growing, and difficult cacti. Principal genera are Echinocactus, Ferocactus, Gymnocalycium, and Parodia.

Echinocereinae

Due to the sub-tribes members' rather prickly appearance it was given the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 name for the porcupine

Porcupine

Porcupines are rodents with a coat of sharp spines, or quills, that defend or camouflage them from predators. They are indigenous to the Americas, southern Asia, and Africa. Porcupines are the third largest of the rodents, behind the capybara and the beaver. Most porcupines are about long, with...

 (echinos). The plants are also mainly low-growing, globular, clustering species. The stems generally have raised ribs or vertical lines of tubercles. There are seven genera in the subtribe, the principal ones being Echinocereus, Echinopsis, and Lobivia.

Epiphyllinae

Almost all epiphytes, these species are unlike the typical vision of cacti. They grow in tropical forests and thrive in hot and damp conditions. They comprise of many branched segments which have a flat appearance - almost leaf-like. Though aerial roots often form, these are no means of support, simply a way of absorbing moisture. Genera typical of this subtribe are Epiphyllum, and Schlumbergera.

Hylocereinae

Most of these plants are either fully epiphitic or partly epiphitic. They have lots of thin, segmented, trailing shoots, and can cling to supports using aerial roots which grow from the base of the segments. The stems are generally triangular in section, or simply winged. There are only nine genera in the subtribe, the principal ones being Aporocactus and Hylocereus.

Rhipsalidinae

As for the Epiphyllinae subtribe, these species are not easily recognised as cacti. They are all epiphytes, absorbing moisture through their aerial roots, and grow in the hollows of trees in tropical forests. The stems develop many branches with very small, spineless areoles. The segments are generally either cylindrical, angular, or flat. The principal genera are Lepismium and Rhipsalis.