I think you're referring to apical dominance. When cut, the main, central, apical meristem is no longer dominant (by inhibitory hormones) over the side meristems, so they start growing faster and soon one or two take on the dominant role, in turn sending inhibitory hormones to the other branches.

Thanks Dean.

I am not sure if you saying the same, sorry.

In most plants if you cut the apical stem, the axillary do not become apical: they just grow to the sides. Thats basically what we do in gardens to make a plant more wide: cut apical bud so plant grows more dense and wide.

However in H helix, the axillary bud in the top position assumes the new role and becomes an apical bud that makes the plant grow up, instead of making the plant grow to a side, as I expected to happen.

That doesnt happen very frecuently does it? Not even in herbaceous species...

Im quite confussed

I think it is a case of removal of apical dominance where the lateral bud shifts from a lateral branch taking up an apical dominance role. This can be seen in trees when topped where one, but usually or more branches grow straight up. Foresters use this technique called pollarding to obtain multiple poles from one tree.

Morning Yago,

Dean is correct in talking about the hormonal control of apical over lateral buds, but as Hedera helix (ivy) is a climber, it also has a number of responses which help it climb, and these will ensure that the lateral buds will attempt to find supporting structures to help them climb up, and the most successful of these will become the new leader.

Ivy is fascinating because it displays skototropic responses, that is a positive growth towards shade, in the shoot which help it find the nearest vertical structure, while the leaves are phototropic, that is they are oriented on the stem to best intercept light. Once a supporting structure is found the shoot is negatively geotropic, that is it grows in the opposite direction to gravity.

Amazing Daniel :)

You are completely right. The stem looks for the wall but the leaves grow with long petiole as the light is much far away. I´ve also observed that behaviour. I ignored anything about the skototropic responses.

So its a "common" plant that is really..."strange" in its behaviour isn´t it?

I bet ivy and/or their buds hide something different that make them interesting to study.

I find it fascinating - so much so that I ended up writing a species account! Dan

Metcalfe, D.J. (2005) Biological Flora of the British Isles: Hedera helix L. Journal of Ecology 93: 632-648.

I think that apical dominance may be more frequent among plants than is generally known. I have found it in underground rhizome system in Butomus umbellatus: many of lateral buds and branches remained dormant for one or several years, but they started to grow after breaking of terminal bud or after disintergation of the system.

Zdenka

Dear Yago,

Yes, what you describe is normal for a vegetative shoot of Ivy, and as you already observed, not all plants (species) have the same response to pruning because they all have their own growth strategy and potential to regeneration.

As mentioned earlier, the fate of lateral buds is controlled intrinsically by hormones that either suppress (auxin) or trigger (strigolactones) branching along an axis, and are thus responsible for the morphological, structural, and functional differentiation of a main axis and its subordinate lateral shoots.

Thus, all plants of a given species should in theory have the same structure (architecture) in identical and undisturbed conditions, and previous works on tropical plants have recognized about 20 architectural H.O.T. (for Halle, Oldeman and Tomlinson) models that account for the whole diversity of vascular plants growth forms and habits .

These models are not perfect and should be used with some caution. However, they have proven extremely useful to model the effects of pruning on fruit trees and design pruning practices to optimize fruit production (apple, mango, apricot, etc..), or other cool things such as the speed and intensity of a fire in a forest.

They are also very useful to predict the results of plant propagation by cuttings and explain why, in some conifers for instance, only the young branches closest to the apex of the trunk can be used to regenerate an entire tree whereas the lower (older) ones can only produce a prostrate form.

I hope this helps and please, let me know if you want more info on plant architecture.

Best,

Julien

Article Plant Architecture: A Dynamic, Multilevel and Comprehensive ...

Thanks a lot to all :)

Hi Yago,

If you're willing to go further on this change of hierarchical status of the lateral bud after cutting, I recommend you to have a look at the articles of Rene Nozeran. You could find a good explanation of what you are describing and other fascinating stuffs in a chapter of the book: Tropical Trees Living Systems. The chapter name is "Multiple growth correlations in phanerogams" written by Nozeran.

All the best,

Tristan

Thanks a lot! I will have a llok at all the references you have provided.

Animals are amazing. But they have a brain (most).

Plants are amazing without a brain.... hope they dont evolve to have it one day :S

Animals are amazing. But they have a brain (most).

plants are doing wonderful job without brain :D so they dont need to evolve it

very true