Secondary growth (growth in width of a stem) Welcome to BFSU: › Forums › Volume Two › Learning Progression “B”: LIFE SCIENCE › Lesson B-22. The Life of Plants II: How a Plant Grows Its Parts › Secondary growth (growth in width of a stem) This topic has 0 replies, 1 voice, and was last updated 4 years, 9 months ago by Bernard Nebel. Viewing 0 reply threads Author Posts February 4, 2019 at 4:20 pm #7400 Bernard NebelKeymaster All growth in height of a tree occurs at the tips of twigs, i.e., apical meristems. The trunk of a tree grows in width, not length. How so? See the following video lecture. Post questions. Author Posts Viewing 0 reply threads You must be logged in to reply to this topic.