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Witch's broom in waterlilies! What comes of it?

 
Fasciated tuber

Fasciation in
Tropical Waterlilies


Fasciated lily now normal

 by Rich Sacher, New Orleans, Louisiana USA
Click images to enlarge
 
The term fasciation (from the Latin, fascia, bundle) is used in horticulture to describe the occasional abnormal growths on a plant. A common name for this phenomenon is witch's broom. One can easily see this type of growth on trees and other plants, since this miniaturized growth occurs in a dense mass on an otherwise normal branch.


Fasciated tuber

Interestingly, most of the miniature conifers which are available in the nursery trade are the result of fasciated growths which have been harvested and vegetatively propagated. Some popular cactus and succulent varieties are also a result of this haywire growth, and they often are referred to as being "monstrose" or "cristate" in form. 

The causal agents of fasciation are quite varied: insects feeding on the growing points of a stem may cause mechanical damage which upsets the hormonal balance in the meristem. Or, the insect may introduce a bacteria or fungus which then disrupts the normal cell division. In some plants, rapid changes in environmental conditions can cause fasciation. Whatever the reason, this abnormality occurs quite often, in a wide variety of plants.

Some fasciations are permanently genetic, and can result in new, stable plant forms, as indicated by the conifers and cacti mentioned above. However, over the years I have seen fasciation in tropical waterlilies. I have been able to repeatedly divide the miniature clustered growths, until they finally resume normal growth. In this case, the cause of the fasciation was temporary, and the plants were able to outgrow that condition when given lots of sun, fertilizer and hot temperatures. My method for accomplishing this is quite simple: divide the tiny plants every three weeks, keeping fertility levels high, with maximum sunlight. The resultant rapid growth somehow overcomes whatever agent was causing the fasciation. Perhaps the heat of summer also aids in repressing the causative agent. I really don't know why this method works … but it does.

This series of photos, taken over a three month period, shows the division of a fasciated waterlily crown, and the eventual return to normal growth in the divisions. We have been able to produce over 50 normal blooming, mature plants in three months, with many more on the way. Yet, even after three months' time, there is still one cluster that continues to fasciate, producing tiny bundles of leaves. I should also note here that I have never seen fasciation spread from one plant to another, no matter how crowded the pond. I have even tried to inoculate normal lilies with tissue from fasciated crowns, but have not been able to induce fasciation in the normal plants.

As fate would have it, this beautiful waterlily is a variety unknown to me! It has deep purple-blue, cup shaped flowers, on tall stems; it is a fast grower, and has proven popular with our customers as an "unnamed hybrid" Although some of the first flowers on these divisions had abnormal shapes, by the second and third flower, all growth was normal. None of the plants which have regained their normal growth have reverted to a fasciated state.

Since fasciation in tropical waterlilies appears to be a temporary and reversible condition, there is the tantalizing possibility that we might some day be able to induce fasciation in a new or rare waterlily hybrid as a means of rapid multiplication. Sometimes, it seems that the more unusual a new hybrid lily is … the more difficult it is to propagate it. Induced fasciation in a new hybrid would enable the production of hundreds of identical plants within one growing season, allowing the trade rapid access to a new and desirable waterlily.

Now, all we have to do is figure this out: is fasciation caused by insect damage? A fungus? A bacteria? Rapid environmental fluctuations? Chance cosmic rays??

As far as I know, all attempts at tissue culture or micro propagation of tropical waterlilies have failed. (I would not consider tissue culture of a viviparous leaf nodule to be useful at all!) So a quick method of multiplying a new hybrid would be highly desirable.

The answer to this mystery of fasciation is more than an academic challenge … it would have great practical consequence in speeding the introduction of new hybrids to waterlily enthusiasts around the world. Understanding how to induce fasciation in waterlilies would be a celebrated accomplishment which would bring joy to hobbyists and hybridizers alike. Got a theory on how to do this? Give it a try, and let us know what happens!


Divisions from the fasciated tuber


Tubers forming on the divisions


Divisions planted


Divisions after 10 days


Divisions after three weeks


Divisions after three weeks


Divisions teased apart in water


Still some fasciation at three weeks

 
Normal left, fasciated right


Normal growth and root systems


First flower six weeks after dividing


Still multiplying six weeks after dividing


Six weeks after dividing


Still some fasciated pups after three months


Flowers at three months


Divisions at three months

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