Because there is (at present) no 'Flower' category as such (it is the default purpose of this website, after all) then leave the Radio-button set to 'Flowers/unspecified', unless, of course, you wish to narrow it down drastically to 'Climbers', 'Crops', 'Grasses' or somesuch.

But if the item you are looking for is a 'Liverwort', 'Moss/Clubmoss', 'Mushroom/Fungi',' Butterfly' or 'Moth, then tick the appropriate radio-button, providing you know for certain which category it comes under. If you don't, then leave it set to 'Flowers/Unspecified', where it will search everything.

For the purpose of this search only:
Grasses includes reeds and sedges
Mosses includes Clubmosses
Mushrooms includes other Fungi

WildFlowerFinder Homepage