Yes. All stem plants grow continuously toward the surface (toward the light which is usually the surface in an aquarium). Depending upon the plant species, the light intensity, and nutrient availability, as it grows the lowest leaves may or may not yellow and drop off. Plants put their energy into new growth and light drives photosynthesis. As the stem tips reach the surface, they may grow along it, or emerge, depending upon the species. You can either leave this (and possibly end up with completely bare lower stems), or cut off the stem tip at some point (leaving several nodes on both pieces) and stick the cut end of the upper portion cut off in the substrate.