If they are arriving in litters, you could stick with one theme per litter
I assume their adopters will rename them, anyway
You could do the lot just from kitchen spices.
eg
Anise, Licorice, Fennel, Cicely
Rye, Caraway, Poppy, Oats, Barley
Cinnamon, Nutmeg, Clove, Ginger, Bergamot
Thyme, Tarragon, Bay, Basil, Coriander, Celery
Cumin, Curry
Lily, Rose, Tulip, Pansy, Voilet, Clematis, Primula,
Oak, Rowen, Cedar, Sycamore, Sitka, Lime, Ash...