In plant reproduction terminology, staminate literally means "bearing stamens." Staminate plant parts, or stamens are "male": i.e., they produce pollen.
Winterberry holly and pussy willows are examples of dioecious plants, with stamens being born on separate, male plants. The female winterberry holly plants are the plants landscaping enthusiasts desire -- for their berries. But male plants, with their stamens, must be included in plantings for fertilization.
With pussy willows, by contrast, it is the male plants that are highly sought after, not the females. The prized "pussy willows" are the staminate catkins -- they are found only on male plants.