Modifiers matching perennial:

• upright,
• ornamental,
• woody,
• tender,
• traditional,
• simple,
• beautiful,
• scented,
• herbaceous,
• tall,
• useful,
• hardy,
• leafy,
• low,
• taller,
• edible,
• subtropical,
• native,
• mature,
• medicinal,
• deciduous,
• larger,
• exotic,
• large,
• soft,
• colorful,
• leggy,
• popular,
• common,
• evergreen,
• small,
• bushy,
• grown,
• tropical,
• sensitive,
• tough,
• smaller,
• vibrant,
• tolerant,
• familiar,
• alpine,
• loving,
• acaulescent,

Simple categories matching tough:

• condition,
• structure,
• veggie,
• material,
• stain,
• shrub,
• polymer,
• application,
• fruit,
• fiber,
• surface,
• food,
• spice,
• substance,
• vegetable,
• rock,
• issue,
• decision,
• soil,
• annual,
• object,
• situation,
• subject,
• job,
• vine,
• iron,
• metal,
• alloy,
• solid,
• area,
• location,
• item,
• state,
• substrate,
• fish,
• hardwood,
• perennial,
• wood,
• junk,
• residue,
• fabric,
• workwear,
• meat,
• stuff,
• fibre,
• plant,
• topic,
• seed,
• plastic,
• appendage,
• times,
• exercise,
• toy,
• bronze,
• grass,
• coating,
• hide,
• leaf,
• part,
• textile,
• stone,
• case,
• animal,
• thing,
• group,
• herb,
• industry,
• contaminant,
• tissue,
• resin,
• paper,
• tile,
• sheet,