The word cactus is derived through Latin from the Greek kaktos, which referred to the cardoon (Cynara cardunculus). Linnaeus in 1753 applied this name generically to a genus he called Cactus, which was later reassigned as a family, Cactaceae, and subdivided into multiple genera Cactuses, the Latin plural cacti, and the uninflected plural cactus are all used in English.
A cactus is a member of the plant family Cactaceae, native to the Americas. They are often used as ornamental plants, and some are also crop plants for fodder, forage, fruits, cochineal, and other uses. Numerous species have been used since ancient times by indigenous peoples for their psychedelic effects.
Cacti are unusual and distinctive plants, which are adapted to extremely arid and/or semi-arid hot environments, as well as tropical environments as epiphytes . They show a wide range of anatomical and physiological features which conserve water. Their stems have adapted to become photosynthetic and succulent, while the leaves have become the spines for which cacti are well known.
Cacti come in a wide range of shapes and sizes. The tallest is Pachycereus pringlei, with a maximum recorded height of 19.2 m, and the smallest is Blossfeldia liliputiana, only about 1 cm diameter at maturity.[5] Cactus flowers are large, and like the spines and branches arise from areoles.
Cacti are perennial and grow as trees, shrubs, or vines. Most species are terrestrial, but there are also many epiphytic species. The leaves may also be tiny and deciduous as can be seen on new shoots of Opuntia. Spines grown by the cacti are actually modified leaves; the stems (the green "pads" of many cacti) have also evolved to photosynthesize.
Grafted Cacti
While no one really knows when people first started to graft plants, a good guess would be that our ancestors mimicked what they observed in nature. Natural grafting occurs regularly. Branches and especially roots of woody trees and shrubs, when held in close contact for prolonged periods of time, will graft. As the stems or roots expand in girth over time, the bark between them is crushed. Cambial contact is made, and a connection between the separate vascular systems differentiates.
GRAFTING is a very interesting method of propagating plants. It consists of uniting a small piece (scion) of one plant with another rooted plant (stock) . The tissues of the two parts make a perfect union, and the scion continues to grow producing the same type of plant from which it was taken, while the root-stock furnishes the food for that growth.
The root-stock does not alter the original characteristics of the plant which is grafted to it except that it may influence its size, rate of growth and profusion of blooms.
Even though grafting does not change the characteristics of the plant, there are some desirable results which may be secured by this process. A species which has sluggish growth and few blooms when grown on its own roots may be grafted on a strong vigorous root-stock that will greatly increase both the growth of the plant and the number of blooms.
Formation of a Graft Union
In order for a graft to be successful, meristematic tissue must develop between the stock and scion, and differentiate into vascular tissues (xylem and phloem). Initially, undifferentiated “callus” cells grow from the vascular cambiums of the stock and the scion. These cells form a callus bridge between the stock and scion and intermingle as they proliferate. If the cells are incompatible, this intermingling does not occur and the graft fails. If the cells are compatible, this bridge of callus differentiates into vascular cambium and vascular tissues. The vascular connection between the stock and scion allows for the translocation of water, mineral nutrition, carbohydrates and other metabolites. Well-formed graft unions are structurally sound, and are no more likely to break than other portions of the stem.
Graft Compatibility
Taxonomic relationships are good guides to graft compatibility. The closer the genetic backgrounds are between the stock and scion, the better the chances of success.
Relationship Grafting Success
Within a species Excellent
Two species within a genus Possible
Two genera within a family Rare
Two families within an order Very rare
Grafting Cacti
Almost any two cacti can be successfully grafted, and produce some interesting forms. Cactus enthusiasts graft to:
» Save plants severely rotted or diseased, by grafting the remaining healthy portion of the plant onto another cactus.
» Ensure better growth and flowering by grafting scions of slow growing species onto vigorous, fast-growing stocks.
» Develop unusual growth forms.
A simple technique for grafting cacti follows:
» With a sharp knife, cleanly cut off the top of a small, upright cactus, several inches above the soil surface. This will be the stock. A plant growing in a three-inch pot, with a one-inch diameter stem would be ideal.
» Remove a small (approximately one-inch diameter), spherical stem from a barrel cactus, and cleanly cut it across the bottom. This will be the scion.
» Set the scion on top of the stock in such a way that at least some of the vascular cambium of each part is in contact. This may require the scion to sit atop the stock a bit off center. The vascular cambium region can be readily seen as a distinct ring on the cut surfaces of the stock and the scion.
» Take two rubber bands of appropriate size, and affix them over the scion and under the bottom of the pot. They will exert a steady pressure on the scion, pressing it against the stock. The two rubber bands should go over the scion at 90 degrees from each other, in order to prevent the scion from shifting. Rubber bands that are too loose will not hold the scion tight enough. Rubber bands that are too tight will cut through the scion.
» Grow the plant as you would any other cactus.
» After a month or two, remove the rubber bands. The scion should be firmly attached to the stock.
» If the graft union failed to knit, cut a new surface on the stock, prepare a new scion, and try again. Practice makes perfect!
