Cristation in cactus and succulents

As a result of unlimited growth of linear meristem (see: photo 1) the stem gets flattened, areolae with spines are situated on all the surface of the crests. The number of ribs and/or of parastichs (spiral lines formed by areoles) increases but the structure of areolae themselves does not practically change. Depending on the age there are fan-shaped (Photo 6), wavy and brain-shaped crests. More thick crests seldom grow into brain-shaped (e.g. crests of Carnegia gigantea). All fasciated species grow faster than normal ones which corresponds to the opinion of most authors, the increase of photosynthesizing surface leads to better carbon nutrition and faster growth of fasciated plants. Crests may remain at any stage for a long time. But at the stage of brain-shaped crest when the curves begin to crowd defasciation (Photo 4) occurs rather often. That is the linear meristem turns into a number of small apical meristems that form normal shoots. Seldom defasciation occurs without any reason at an earlier stage of the development of the crest. In general with age meristem gets less active or not active at all. The growth continues only at some parts of linear meristem. Thanks to this process the upper surface becomes uneven. The more active parts are usually situated at its ends. This type of developing crest prevails among cacti, and for a long time it was considered to be the only possible.

(Photo 4)

Mammillaria luethyi

forma cristata

an example of crest defasciation



(Photo 5)

Strombocactus disciformis

forma cristata

Juvenile and mature structure in response to the use of different grafting stocks. Many authors affirm that the crest of cacti has another specific feature. In spite of their rather large size the areolae frequently kept their juvenile structure and are situated like at the seedlings of the species.

Consequently the physiological age of crest may not depend on its real age and be determined by the stage of the development at which it appeared. It is quite possible that the crest that appeared at a juvenile plant will not be able to bloom during its life-time.



But this thesis is not based on a correct observations, the apparent age of the crest depends mainly by the hormonal balance furnished by the grafting stock. It is a well known phenomenon that crest grafted on different stocks may be very different one from each other.

The fact that crest forms flowers rarely is in part due to the consuetude to graft the crest on strong stock that enhance only a fast growth and delete the natural maturation and flowering. (photo 5)

In the ontogenesis a crest can appear any time, but development of crests at large columnar cactus species ( such as in saguaro Carnegia gigantea) in the early stages of ontogenesis is unlikely. On the other hand small species may crest early already at the cotyledons stage.

That means fasciations can take place even in the first days of a seedling or at the stage of the forming of the embryo in the seed. As practice shows when cactus fanciers grow cacti out of seeds fasciations often take place at germs and juvenile plants especially when the regime changes (temperature, humidity, grafting onto a strong stock). It also takes place in any growing phases without any apparent reasons.



(Photo 7)

Echeveria coccinea

San Bartolo Co. Hidalgo,

Mexico forma cristata Cultivation of crested cacti and succulents.

Cultivation of the cristate forms of cacti is worthy of a special mention because an accidental appearance of a crest happens quite often and these plants attract attention of collectors thanks to their prominent ornamental features. Furthermore the crested forms can be usually reproduced vegetatively without difficulties Many crests should be kept on the dry side, in other words, grown hard. Too much water and/or fertilizer can cause cracks and spreading. Trimming any normal shoots off helps the crested form grow better and truer to form, but sometimes these normal shoots can crest again after some normal growth. Cuttings from crested cactus should be grafted for best results. Cuttings from other crested succulents can be replanted after the normal waiting period. Keep these very dry for at least a week or preferably two weeks and on the dry side during their normal growing cycle. For euphorbias, this would be in the Autumn.