This article throws light upon the top three tribes of cactus plants. The tribes are: 1. Pereskieae 2. Opuntieae 3. Cereae.
Tribe # 1. Pereskieae:
This is the primitive form and near to original forest trees. Plants are leafy bushes, look like citrus trees and have stalked flowers in clusters resembling wild roses. Spines are present but not glochids or barbed bristles e.g. Pereskia grandiflora commonly known as rose cactus and Pereskia aculeata are members of this group.
Tribe # 2. Opuntieae:
Plants are characterized by the glochids or sharp, easily detached bundles of barbed bristles in the aerioles. Stem or branches are fleshy, loosely joined either flat or pad like or cylindrical having spines but without ribs. Flowers are without petioles and tubes and are generally of wheel shape e.g. Opuntia sp.
Tribe # 3. Cereae:
This is the largest group and members are characterized by their ribbed, fleshy stems of continuous growth in columns or globes. Glochids are absent from areoles. Flowers are tubular and are very showy except Riphalis section. They are attached directly on the plant without stems.
This tribe being the largest one has further been divided into 8 sub-tribes:
1. Cereanae:
Members are known as column or torch cacti. Branches are numerous and ribbed. Funnel shaped flowers appear on the top e.g. cereus, cephalocereus, cleistocactus, Trichocereus.
2. Hylocereanae:
These have vine like habit with aerial roots clinging to trees and rocks. Mostly are night blooming cacti with large flowers. Important genera are: Selenicereus, Hylocereus, Weberocereus, Crypto-cereus, etc.
3. Echinocereanae:
These are low, growing in clusters or in single and heavily ribbed. Flowers are bell shaped, showy and appear on the side of the stem. Important genera are: Echinocereus, Echinopsis, Rebutia, Chamaecereus, etc.
4. Echinocactaenae:
These also grow low and are small and sometimes forming clusters, ribbed and spiny. Flowers are most beautiful e.g. Astrophytum, Echinocactus, Ferocactus, Notocactus, Gymnocalycium, etc.
5. Cactanae:
These are commonly called as Melon cactus or Turk’s cap. These can be easily identified by the presence of wooly or bristly, cap like structure on the top of the globular body. Flowers arise from the tops e.g. Melocactus.
6. Coryphanthanae:
It is popularly known as Pincushion cacti. Plants are globe shaped. Stems are small forming large clusters with tubercles or nipples in rows. Important genera are: Mammillaria and Coryphantha.
7. Epiphyelanae:
These are mostly epiphytic and tropical. Branches are flat and leaf like of usually without spines. Flowers are showy e.g. Zygocadus and Epiphylllim.
8. Rhipsolidanae:
It is commonly called as chain cacti. These are freely branching with slender, cylindrical or flat branches. Stems are pendant forming dense masses on trees of tropical forests. They bear tiny flowers and berries. Important genera are Rhipsalis and Rhipsalidopis.