KNOP, A COMPONENT OF A STEM USED FOR ORNAMENTATION AND STRUCTURE
KNOP STYLES
The Corning Museum of Glass defines a knop as: A component, usually bulbous, of the stem of a drinking glass, hollow or solid, used either singly or in groups, and placed contiguously or with intermediate spacing; also the finial at the center of a lid. For more information about knop styles see, An Illustrated Dictionary of Glass by Harold Newman, 1977 P.172.
Below you will see a variety of knop styles from the Allaire Collection and from the collection of Elisabeth and Theo Zandbergen. This link is to Elisabeth and Theo Zandbergen their blog page.

Facon de Venise Wine Glass from Elisabeth and Theo Zandbergen from northern Netherlands 17th Century. This fine wine glass has a so called rounded bucket bowl, see Bickerton, which is an almost cylindrical cup slightly, rounded of at the bottom. A bucket bowl is one of the rarer forms for this type of glass. The very large diameter foot is also quite typical for glasses from this period see also the glass with the two hollow knops. The cup set directly on a merese which on a second smaller merese and then attached to the top part of the pointed hollow knop. At the bottom part of the knop is again a small merese, followed by a short solid section connecting thru a flattened knop to the almost flat foot with turned in rim. The stem construction is a so called inverted baluster.
Knoptastic!