1. the idea that the sporophyte generation and the gametophyte generation follow one another in alternating fashion perennial 2. the process of changing cells or organisms from a generalized to a more specific or specialized condition; often involves a reduction of the ability to reproduce or divide and is usually not reversible meristem 3. beginning period of growth of a seed or spore; to sprout differentiation 4. the youthful, undifferentiated cells of root and shoot tips and other plant parts that produce new cells for growth alternation of generations 5. a plant that continues to grow year after year from the same plant body germination 6. above ground part of a plant; leaves, stems, flowers, fruits, etc. vascular cambium 7. the meristematic cells that produce new cells, increasing plant body girth; often forming a ring only several cell layers wide in woody stems and roots shoot