Comment Comment by WorkerBee28474 Another answer is: They're not - at least in some plants:https://en.wikipedia.org/wiki/Valonia_ventricosahttps://en.wikipedia.org/wiki/Acetabularia parent WorkerBee28474 4 months ago
https://en.wikipedia.org/wiki/Valonia_ventricosa
https://en.wikipedia.org/wiki/Acetabularia