What makes annual plants "annual" and perennial plants "perennial?" It's all in the life cycle. Botanically speaking, annual plants complete their life cycle in one year:
- You place the seeds of last year's annual plants in the ground in spring
- New annual plants sprout from the seeds
- With proper care, during the course of the summer, these annual plants produce flowers
- Toward the end of the growing season, annual flowers yield seeds -- signaling to the annual plants that their life cycle is complete
The Difference Between Annual Plants and Perennials
Thus the difference between annual plants and perennials. For perennials usually don't produce flowers their first year (grown from seed) but make up for it by flowering more than 1 year. That is, they have a longer life cycle.
Some plants that are perennials in their native (e.g., tropical) lands are treated as if they were annual plants in colder regions. Here, one might say that usage trumps botany. E.g., lantana plants are, technically, perennial, but they're treated as annual plants in regions far to the north of their ancestral home -- regions too cold for them to complete their life cycle.
Some folks understand all that but still have trouble with the words, "annual plants" and "perennial plants." If you can't seem ever to remember which is which, use the following as a mnemonic device:
- The root in both words, "annual" and "perennial" (i.e., per-annual) is the Latin word for "year," annus
- Annual plants are thus those that last but a year in their native climes
- Perennial plants have something extra: that "per" in their name. The per- prefix in Latin intensifies or adds to what comes after it. So perennials live additional years, when compared to annual plants.
