using the q parameter to filter for taxa on lists seems to be unreliable. it’s better to use the taxon parameter like so: https://www.inaturalist.org/places/hawaii#taxon=acacia.
although you can query taxa like this in the URL, unfortunately, it doesn’t look like there’s a user interface on the page to query for specific taxa other than the iconic taxa on the left side of the page. however, you could click the link on the left side of the page to go to the checklist page, and that page will have an interface to search for taxa. see https://forum.inaturalist.org/t/items-in-list-not-always-returned-when-searching-for-genus/59630.