Premise: Cerastium is a genus of annual, winter annual, or perennial plants belonging to the family Caryophyllaceae. They are commonly called mouse-ear chickweed. Species are found nearly worldwide but the greatest concentration is in the northern temperate regions. There are about 200 species. A number are common weeds in fields and on disturbed ground.
Hypothesis: Cerastium are the most common weed, with about 200 species.