Between a pre-1964 survey and its 2019 update, a single rural county in southeast Kansas went from 693 documented vascular plant species to 1,134 — a 64% increase. But the fastest-growing segment of the flora isn't native wildflowers. It's weeds.
Crawford County sits in the Ozark border region of Kansas, a landscape of tallgrass remnants, post-mining succession, and agricultural edges. Two comprehensive plant inventories bookend more than half a century of ecological change: the ESG checklist (pre-1964) and the PEA update published in 2019. Comparing them reveals not just a richer species list, but a shifting balance between native and non-native plants.
The chart above shows how dramatically individual families expanded. Poaceae (grasses) jumped from 66 to 154 species; Asteraceae (composites) from 74 to 151. Together those two families now account for 27% of all species in the county. Cyperaceae — the sedges — nearly doubled, climbing from 40 to 77 species, a 93% gain that likely reflects better survey coverage of wetland habitats.
The non-native surge
Raw species counts grew across the board, but non-native taxa grew disproportionately. ESG documented 88 non-native species (12.7% of the flora). By PEA's count, that number had risen to 200 non-native species — 17.6% of the total. That's more than a doubling in absolute terms, and a meaningful shift in the county's ecological makeup.
The native-vs.-non-native breakdown makes the trend unmistakable. While native species also grew substantially (from 605 to 934), the non-native fraction climbed five percentage points — a signal that introduced plants are colonizing Crawford County's disturbed soils, roadsides, and old mine lands faster than botanists once appreciated.
Not every family is equally invaded. Brassicaceae and Caryophyllaceae each have 44% non-native species in the PEA inventory — nearly half of their members are introductions. Poaceae, despite being the largest family, sits at a more moderate non-native fraction. The pattern suggests that certain life-history strategies (annual, fast-germinating, disturbance-adapted) make some lineages far more hospitable to invaders.
149 ghost records
The comparison also exposed a forensic problem: 149 taxa reported in the original ESG checklist could not be confirmed. Voucher specimens were missing, misidentified, or simply never located in herbaria. That's nearly 1 in 5 of ESG's records — a reminder that a species name on a checklist is only as reliable as the specimen behind it.
Meanwhile, 31 additional taxa were newly reported after the PEA study, suggesting the county's flora is still being refined with each collection trip.
What this means for Kansas biodiversity
Crawford County's story is likely not unique. Across the Great Plains, decades of land-use change, improved survey effort, and accelerating plant introductions are reshaping local floras in ways that only careful, specimen-backed inventories can document. The next question isn't whether the list will keep growing — it's whether the native-to-non-native ratio will keep sliding, and what that means for the prairie fragments that remain.