Mixed bouquets containing both flowers and foliage are generally classified under heading 0603 (cut flowers) based on the essential character of the article. Pure foliage, branch, or grass shipments with no flowers or buds belong under 0604. When in doubt, the heading that most specifically describes the predominant component governs.

Yes — even dried or preserved plant material can harbor regulated pests or pathogens, and USDA APHIS retains authority to inspect and potentially refuse entry. Certain mosses and lichens are also subject to specific quarantine conditions depending on origin country, so importers should verify current APHIS requirements before shipment.