Subfamily Cactoideae: no leaves*, no glochids.Subfamily Opuntioideae: fleshy round leaves present or absent, glochids present.Īustrocylindropuntia, Brasiliopuntia, Consolea, Corynopuntia, Cylindropuntia, Cumulopuntia, Grusonia, Maihueniopsis, Micropuntia, Opuntia, Pereskiopsis, Pterocactus, Quiabentia, Tacinga, Tephrocactus, Tunilla.(or Maihuenia may be separated into Subfamily Maihuenioideae.) Subfamily Pereskioideae: broad leaves, no glochids.This family contains numerous genera which seem to be constantly under revision. Recent DNA studies support the general groupings, but suggest some taxonomic rearrangements of species. However, as cacti are not well-represented in the fossil record, the logical taxonomic sequence is based mainly on morphology. Various authors have estimated that the Cactaceae evolved as recently as in the last 10,000 years or as long ago as 20 - 30 million years.
All species of cacti are protected as CITES 1 or CITES 2 plants, which presents a barrier to free trade even for nursery grown cacti and artificial hybrids with no natural distribution.Ĭactus taxonomy appears to follow a record of their assumed evolutionary history. Echinocactus grusonii are far more common in cultivation than in their habitat, much of which was destroyed by construction of a reservoir. Many species of cacti are cultivated as ornamental house plants or for dry landscaping and they are grown from seed in vast numbers. In some places cacti have become invasive weeds. Through introduction, Cactaceae and especially Opuntia are found throughout the tropics. Opuntia ficus-indica, Selenicereus sp., Hylocereus sp.) or fruit is collected from wild plants. Uses: Several species of cacti are cultivated for their juicy fruit (e.g. Ferulic acid in the cell walls of Cactaceae is also a common characteristic. Betalains are responsible for the red or violet colouration of some cacti when stressed.
Betalains and anthocyanins never occur in the same plant. Betalain pigments are present and characteristic of the family Cactaceae and of the Order Caryophyllales in which they are included, as is absence of anthocyanin pigments found in many other families of flowering plants. Fruits are generally berries with multiple seeds, which may be surrounded by juicy flesh or by a more or less dry membrane and may have external areoles with spines or glochids.īiochemistry: CAM metabolism allows carbon-dioxide to be taken up during cool nights and stored as malic acid for use in photosynthesis during hot, sunny days, greatly reducing water loss during transpiration. Leaves where present are alternate, but usually reduced or absent. In some cactus species, spination is minimal, or occurs only during some phases of the succulent plant's life or vestigal spines are present as hairs. spiny Euphorbias, that sometimes branch above the plant body.
These should be distinguished from solitary spines or thorns on other plants e.g. Water loss is reduced by a waxy epidermis.Īll Cactaceae have distinctive modified buds that have evolved into specialised areoles from which grow multiple spines and glochids (right). Many cacti have ribbed bodies that allows easy expansion in response to water uptake after brief showers of rain and contraction in times of extended drought. Some species have tuberous roots or a fleshy taproot. Morphology: Most species of Cactaceae are spiny stem succulents, although there are a few woody shrubs ( Pereskia) and more or less succulent epiphytes. Cacti generally have 22 chromosomes but African variants of Rhipsalis baccifera are tetraploid. Cacti are exclusively native to the American continent including the West Indies with a solitary exception of the epiphytic Rhipsalis baccifera which is distributed in Africa, Madagascar and Ceylon as well as in South America, Mesoamerica and the Caribbean. The large family Cactaceae is one of the most distinctive familes of dicotyledenous flowering succulent plants, with around 90 genera and 2500 species, ranging in size from less than half an inch to tens of feet in height. Cactaceae - Cactus Family Linnaeus (1737) Greek: kaktos = a prickly plant (Spanish artichoke) from Sicily.