The bud vase is a small vase, usually with a narrow stem made to hold a single flower.  The shape also emulates the shape of a real flower bud, rounded bulb like appearance.

Of course, you can put a pair of flowers or a small bouquet in a bud vase, but it's meant to show off the boldness of a single stem.

Bud Vase flower ideas

Flower Ideas for a Ceramic bud vase: Hydrangea all by itself, one rose, Two or three tulips, A single orchid on its own, One stem of a bird of paradise. A small bunch of yellow sunflowers, Iris in a bud vase that is tall, A tiny group of peonies