Heteroblasty

Heteroblasty is the significant and abrupt change in form and function, that occurs over the lifespan of certain plants.

Characteristics affected include internode length and stem structure as well as leaf form, size and arrangement.

[3] Some characteristics affected by heteroblastic change include the distance between successive leaves (internode length) and stem structure as well as leaf form, size and arrangement.

This random spread of heteroblastic plants across species is believed to be caused by convergent evolution.

[6] The term heteroblasty was coined by the German botanist Karl Ritter von Goebel, along with homoblasty for plants with leaf characteristics that do not change significantly.

Leonard Cockayne observed that heteroblasty occurred in an unusually high proportion of tree species native to New Zealand.

Many hypothesize that heteroblasty is a result of natural selection for species, that can best survive in both low and high light environments.

[9] It is also hypothesized that auxin and cytokinin when working together can cause the sudden change in phyllotaxy of heterogenetic plants.

[1] The gene ABPH1 has been found to code for cytokinin and when changed in a mutant affected the plant's ability to regulate the phyllotaxy of the stem.

All listed are plants, because they are the only organisms that have been found to undergo this growth change it is absent in animals, fungi, and microbes as far as is known to this point.