Ask Mr. Smarty Plants

The answer to your question is yes ... and possibly, no.  Confused?  You're not alone.  The question of the nativity of Achillea millefolium (common yarrow) is a toughie.  The crux of the problem is how yarrow is classified taxonomically.  If you don't recognize any botanical varieties within the species then the answer is simple; yes, it's native to Texas as well as nearly all of North America, Europe, most of Asia, the Indian sub-continent, and even part of Mesoamerica.  In other words, it's a cosmopolitan species.

However, some taxonomic authorities recognize two or more botanical varieties.  Our authority, The USDA Plants Database (based on the Synthesis of North American Flora), recognizes 12 botanical varieties (not all native) as occuring in North America.  One botanical variety, Achillea millefolium var. occidentalis (western yarrow) was growing in Texas at the time of the arrival of the Europeans and thus is considered native to Texas.  Many garden varieties of Achillea millefolium are progeny of Old World botanical varieties and are not native to Texas or North America.

There are good arguments to be made for recognizing no varieties (lumping) and also for recognizing botanical varieties (splitting).  Because, by policy, we follow the lead of our taxonomic authority the decision is made for us.  In this case we recognize one botanical variety of common yarrow as a Texas native.