Modifiers matching river:

• special,
• clear,
• small,
• larger,
• large,
• sensitive,
• perennial,
• major,
• nearby,
• fast,
• beautiful,

Simple categories matching perennial:

• host,
• plant,
• issue,
• native,
• herb,
• allergen,
• grass,
• antigen,
• seed,
• crop,
• pasture,
• bunchgrass,
• legume,
• vegetable,
• tree,
• flower,
• forage,
• fruit,
• shrub,
• wildflower,
• pest,
• river,
• group,
• veggie,
• planting,
• weed,
• vine,
• species,
• ornamental,
• clover,