Ask Mr. Smarty Plants

Ahhhhh....Mr. Smarty Plants loves these "why is the sky blue" type questions especially those that have to do with plant reproduction and evolution. So here goes. Most of the big bloomers are annual plants and their strategy is to germinate, grow, bloom synchronously, reproduce, produce many seeds, then die in a one year span. That strategy has evolved over millennia and it requires large number of individuals participating to be effective. If only a handful of annuals participated, there is a good chance they wouldn't "find" each other to breed and the population would go kaput.

Now, let's compare that to perennials. Because they live multiple years, they have multiple opportunities to reproduce and can invest more time and resources in growing vegetatively. Large numbers are not required for reproduction since a missed opportunity in one year could be made up in the next year. Compared to annuals, they have a much higher expectation of future life.

Of course, there are other reasons plants might be rare including loss of pollinators, seed dispersers, habitat destruction, etc. There are also other reasons plants can be more common including human intervention, favorable environmental conditions, invasive, etc.