NASA Clean Air Study: Certain plants remove many harmful polutants from the air
Art of making miniature nature
Japanese. Emphasis on one or more miniature trees. (example images below)
Japanese. Emphasis moved from just trees,
to also being an entire landscape, including more emphasis on stones, soil, & the shape of the ground. (example images below)
Vietnamese miniature nature landscapes, imitating the scenery of the islands, mountains, & surrounding environment. (example images below)
Chinese. Tree type & shape is less stringent than bonsai.
Pots are often flamboyant compared to bonsai's "minimalist" style.
Japanese zen/dry/rock garden (example images below)