| [College of ACES] | [University of Illinois] | [Illinois CES] |
Tree growth can either be pre-formed or neo-formed: pre-formed is what is set in the buds at the end of the growing season; neo-formed is growth that occurs during the growing season. Many species have only pre-formed growth and once that growth is completed (bud break, shoot extension, bud set), that's it for the season (except when unseasonably warm weather causes the new buds to break in the fall, another story). These trees also have true terminal buds (if I remeber correctly). Aspen has both pre-formed growth and neo-formed growth as the apical meristem continues to initiate growth, after the pre-formed growth is extended,until frost. Aspen does not set a true terminal bud.
I know that there are other trees that have these characteristics but I am amazed that I could remember that mutch from my distant education past. I hope this answers your question.
Nancy