Regarding observation https://www.inaturalist.org/observations/22867765#activity_comment_2792331
I’ve been down this rabbit hole before! There’s been a serious confusion of scientific names and even species concepts for a couple small weedy grasses. I think Flora Europea has them confused.
Fern-grass = Catapodium rigidum = Desmazeria rigida = Sclerochloa rigida. (W3Tropicos & USDA Plants) This observatoin is Desmazeria rigida, and it’s Catapodlium rigidum. So far so good. They should have the same common name, but in iNaturalist one is Fern-grass and one is Hardgrass.
Hard Grass = Sclerochloa dura. (W3Tropicos & USDA Plants) iNaturalist uses Hard Grass (or Hardgrass) as the common name for Sclerochloa dura.
iNaturalist needs to fix this!