Editing Cactus (section)

===Growth habit===

Cacti show a wide variety of growth [[habit (biology)|habits]], which are difficult to divide into clear, simple categories.

; {{vanchor|Arborescent cacti}}
Cacti can be tree-like (arborescent), meaning they typically have a single more-or-less woody [[Trunk (botany)|trunk]] topped by several to many [[branch]]es. In the genera ''Leuenbergeria'', ''Pereskia'' and ''Rhodocactus'', the branches are covered with leaves, so the species of these genera may not be recognized as cacti. In most other cacti, the branches are more typically cactus-like, bare of leaves and bark and covered with spines, as in ''[[Pachycereus pringlei]]'' or the larger [[opuntia]]s. Some cacti may become tree-sized but without branches, such as larger specimens of ''[[Echinocactus platyacanthus]]''. Cacti may also be described as [[shrub]]by, with several stems coming from the ground or from branches very low down, such as in ''[[Stenocereus thurberi]]''.{{sfnp|ps=none|Anderson|2001|pp=15–37}}

; {{vanchor|Columnar cacti}}
Smaller cacti may be described as columnar. They consist of erect, cylinder-shaped stems, which may or may not branch, without a very clear division into trunk and branches. The boundary between columnar forms and tree-like or shrubby forms is difficult to define. Smaller and younger specimens of ''[[Cephalocereus senilis]]'', for example, are columnar, whereas older and larger specimens may become tree-like. In some cases, the "columns" may be horizontal rather than vertical. Thus, ''[[Stenocereus eruca]]'' can be described as columnar even though it has stems growing along the ground, rooting at intervals.{{sfnp|ps=none|Anderson|2001|pp=15–37}}

; {{vanchor|Globular cacti}}
Cacti whose stems are even smaller may be described as globular (or globose). They consist of shorter, more ball-shaped stems than columnar cacti. Globular cacti may be solitary, such as ''[[Ferocactus latispinus]]'', or their stems may form clusters that can create large mounds. All or some stems in a cluster may share a common root.{{sfnp|ps=none|Anderson|2001|pp=15–37}}

; Other forms
Other cacti have a quite different appearance. In tropical regions, some grow as forest climbers and [[epiphyte]]s. Their stems are typically flattened and almost leaf-like in appearance, with few or even no spines. Climbing cacti can be very large; a specimen of ''[[Hylocereus]]'' was reported as {{convert|100|m|ft|sp=us}} long from root to the most distant stem. Epiphytic cacti, such as species of ''[[Rhipsalis]]'' or ''[[Schlumbergera]]'', often hang downwards, forming dense clumps where they grow in trees high above the ground.{{sfnp|ps=none|Anderson|2001|pp=15–37}}
{{center|'''Growth habits of cacti'''}}
<gallery mode="packed" heights="155" style="font-size:95%; line-height:120%">
Pereskia aculeata5.jpg|Treelike habit (''[[Pereskia aculeata]]'')
Cardon Pachycereus pringlei.jpg|Tall treelike habit (''[[Pachycereus pringlei]]'')
Cephalocereus columna-trajani rev.jpg|Tall unbranched columnar habit (''[[Cephalocereus]]'')
Ferocactus1.jpg|Shorter clustered columnar habit (''[[Ferocactus pilosus]]'')
Ferocactus echidne var victoriensis 1.jpg|Solitary globular habit (''[[Ferocactus echidne]]'')
Rebutia flavistylus 2 rev.jpg|Clustered globular habit (''[[Rebutia]]'' species)<!--image info implies R. flavistyla, but Anderson p.603 says "usually solitary"-->
Rhipsalis paradoxa.jpg|Epiphytic cactus (''[[Rhipsalis paradoxa]]'')
Great Variety of Cacti at the Desert Botanical Garden.jpg|There is a wide variety of cacti at the [[Desert Botanical Garden]]
</gallery>