"供观赏的植物" can be translated into English as "ornamental plants" or "decorative plants".
"Ornamental plants" is the more commonly used term in horticulture and botany, referring specifically to plants grown for their aesthetic value, such as flowers, foliage, or form.
"Decorative plants" is a broader term that can also be used, though it might be slightly less specific in a botanical context.
In most cases, "ornamental plants" would be the preferred choice.