Leather leaf is a very inexpensive greenery used in every flower shop. It is available all year round.
Grower's bunch usually have between 17 - 20 stems per bunch. Each stem has laterals that can be cut off and used as smaller insertions into centerpieces.
Here I've cut off and started greening in the lower right half of the centerpiece with leather leaf fern.
Another common greenery with longer laterals is Israeli Ruscus. It has rounded leaves that branch out longer, slender stems.
I inserted a few stems of Israeli Ruscus high on the left side, counterbalancing the height of the glass.
I continued to fill in around the foam with more ming fern.