A leaf "frond" is a part of an entire leaf, such as the leather leaf frond shown below. I cut these off the main stem with a knife. It gives me a clean, sharp edge that pokes cleanly into florist foam.
You may have to strip off the bottom leaf or two before inserting into the bouquet holder.
I'm using leather leaf to "fill in" the bouquet and cover the mechanics of the foam. The greenery is actually going to be a part of the design.
The outer ring of leaves will determine the final size of the bridal bouquet. The flower heads commonly edge out beyond the rim of greenery. In this case, however, I want a greenery "collar" of galax leaves to show as part of the final design.
I also fill in the underside of the bouquet holder. You'll see special openings where you can still see foam. This helps conceal the bouquet holder and helps contribute to the look of a "mock" hand tied bouquet later.
Fill in enough to cover the mechanics. Don't go overboard, since this is the underside of the bouquet. Notice how the "right" side of the fern is facing downward, rather than the underside.
I've filled around the edges and established the size of the bouquet. Now I'm going to fill in with a collar of galax leaves.