It sometimes happens that the last specimen of a valuable species dies and it's impossible to rescue it as only a thin and weak part of the plant remains. It's no good trying to graft or root it. This situation made us look for new ways of rescuing dying plants. We found it by accident when the only species of Neochilenia malleolata  (F. Ritter) Backbg. was dying. Only several tubercles with areoles remained healthy. As we were grafting seedlings on Peireskiopsis  we decided to try grafting healthy areoles on it. The results were amazing. All the areoles were grafted successfully and in a month they gave new plantlets that grew well and the next year two of them even bloomed. The same year we succeeded in grafting areoles of two species of Coryphantha  onto Peireskiopsis . We haven't found any data about propagating cacti by grafting areoles onto Peireskiopsis  in special literature. Separate mammillae of Mamillaria plumosa  A. Weber. were grafted onto Peireskiopsis spathulata  (Otto). Britt. et Rose. Glase and Foster point [2] that when they grafted Mamillaria meleleuca  a new plantlet arose near the basis of the mammilla, not from the areoles. The author doesn't mention what species was used for the stock but judging by the photo it might be an Eriocereus jusbertii . He also says it's a good method of propagating rare species if one doesn't want to behead the plant.

The types of areoles are shown in picture 1.

Photo 1. Types of areoles (according to Buxbaum [with changes): / - theoretical radial areole; // - two-sided ordinary areole: /// - oblong areole with a crest-like arrangement of spines; IV - growing point near the upper part of areole in a groove (Hamatocactus), V - growing point and areole came apart but are still connected by the groove (type Coryphantha )', VI - growing point and areole came apart completely (type Mammillaria ). 1 - growth point; 2 - a part of areole with spines; 3 -groove.

When propagating cacti by areoles one should take into consideration the location of growth point in the areole (as it is the only point where a new plantlet can start) and the activity of growth points in the areole. Meristematic tissues of young areoles are more able to form new plants than old ones. Nevertheless, even very old areoles of some species can give not only spines but also lateral shoots and flowers. Unfortunately, detailed information concerning the activity of growth points of areole is too scarce. To wake up meristems in areoles it is necessary to give them an impulse (usually it means to behead the cactus) which makes for active inflow of nutritive elements.

Grafting cacti on stocks with good roots also makes growth points wake up. This is especially true for the cacti grafted on Peireskiopsis . Cactophiles achieved remarkable results in propagating rare plants beheading them so they could fit for Peireskiopsis . An areole grafted onto Peireskiopsis  yields to the stock's stimulant action.

For grafting, we cut out an areole with a piece of tissue of tubercle or rib. The thickness depended on the peculiarities of the species and usually was 2-5 mm. The areoles were grafted on the upper part of the stem of Peireskiopsis , 3-6 cm from the top. It's rather difficult to graft areoles on the very top as their diameter was larger than that of Peireskiopsis . The spines of the areoles were cut out with the scissors as it's almost impossible to fix the graft without doing it. We used a thin medical rubber and elastic thread to fix it (pic. 2)

Photo 2. Fixing areole on the stock.

As the growth point is in the upper part of the areole, the scion should be placed on the stock so that the zone under the growth point would be on the cambial ring of Peireskiopsis . It helps develop a system of conductive tissues between graft and stock.

The grafted plants were placed into a closed hotbed at 20-35 Centigrade. When active growth of the scion was observed the plants were moved onto the shelves of the greenhouses.

Areoles of cacti from 36 genera were successfully grafted. The best results were obtained by grafting areoles of Neochilenia  plants. Areoles of all eight species in this genus gave plantlets. Similar results were obtained also within the genera Coryphantha, Islaya, Neoporteria, Oroya, Sulcorebutia , though the amount of tested species in these genera (2-3 sp.) excludes the possibility to estimate the properties of the whole genus. Areoles of most species which did not give new plantlets were grafted in September or the beginning of dormancy period. It is partly proved by the fact that the areoles of Copiapoa barquitensis  did not give new plantlets when grafted in September, but gave 3 plantlets out of 6 areoles when grafted in May.

Various results were got after grafting Echinocereus, Echinofossulocactus, Mammillaria, Notocactus  and Parodia . If we look at Efc. coptonogonus  and Efc. violaciflorus  only their upper areoles gave new plantlets after grafting. The areoles of Efc. coptonogonus  and Efc. violaciflorus  though partly took and became fuzzy (which usually precedes developing new plantlets of other species) did not give new plants. It is interesting to note that the areoles of Efc. coptonogonus  did not give new plantlets even after the scion was beheaded and grafted onto a strong stock of Peireskiopsis . New plantlets arose around the central cylinder of conductive tissues. We also observed this phenomenon with some plants of Roseocactus  grafted on Peireskiopsis  and with young seedlings of Astrophytum asterias  on their own roots after they were beheaded for grafting. We grafted areoles of two colored forms of Gymnocalycium mihanovichii  on Peireskiopsis  too. They took well, gave new shoots, but the young plants turned to be unstable and died during the winter. The development of new plants was determined by the biological activity of the growth points of the areole. The areoles of the species that develop lateral shoots well gave new plants quicker after grafted on Peireskiopsis  than those for which lateral shoots are untypical. The development of new plants shows that the activity of the growth points of areoles is different. Neochilenia yanbaeli  gave new plants almost simultaneously. The rest of the species gave plantlets gradually.

Examining cuts of grafted areoles showed that the right position of areoles on the graft is an important factor for waking growth points. On picture 3 the growth point of grafted areole is above conductive tissues that facilitates developing a single system of conductive tissues and consequently wakes the growth point and gives a new plantlet. So, grafting separate areoles of cacti on the stock of Peireskiopsis spathulata  (Otto) Britt. et Rose have good prospects for propagating rare plants, for rescuing dying plants, or when it is necessary to obtain in a short time great number of genetically similar plants. Best results were obtained when grafting areoles of Coryphantha  and Neochilenia  as well as Islaya, Neoporteria, Oroya, Sulcorebutia .

The structure of areoles should also be taken into consideration. A tubercle, a piece of a rib or mammilla with areole should be placed on the stock so that the growth point of the areole be above the conductive tissues of the stock.

50 taxa from 22 genera of the family Cactaceae were grafted onto Peireskiopsis spathulata  (Otto) Britt. et Rose to prove the possibility of propagation of cacti by grafting separate areoles. The areoles were cut with thin layer of plant tissue and attached by thin medical rubber. The best results were obtained by grafting areoles of Neochilenia  plants. Areoles of all eight tested species in this genus gave plantlets. Similar results were obtained also within the genera Coryphantha, Islaya, Neoporteria, Oroya, Sulcorebutia , though the amount of tested species in these genera (2-3 sp.) excludes the possibility to estimate the properties of the whole genus. Different results were acquired with the genera Copiapoa, Echinocereus, Echinofossulocactus, Mammillaria, Notocactus  and Parodia . The plantlets arose from new areoles better than from old ones. No plantlets were obtained by grafting areoles from genera Astrophytum, Espostoa, Krainzia, Matucana  and Phellosperma , but the failure may be explained by the fact the grafting was done in September. The method of propagating cacti by grafting areoles may be of great importance for propagating rare plants, for rescuing dying plants, or when it is necessary to obtain in a short time great number of genetically similar plants.

1. Buxbaum F. Morphology of cacti. Sect. 1 Roots and stem. Pasadena, Calif., Abbey Garden Press, 1950.
2. Glass C., Foster R. Will's new. - Cactus & Succulent J., 1978, vol. 138.

Text sent by Dm. Petrov, Voronezh, Russia