How to Tell a Male Grapevine From a Female Grapevine

Examine the flowers for a stamen, the male reproductive part. Grape flowers are small and lack petals so use a hand lens to see details clearly. The stamen is made up of paired anthers that hold pollen. Anthers look a little bit like bowling pins, with yellow powder. This powder is pollen, the male genetic material, or sperm. Anthers are supported by long, thin stalks called filaments. Generally, there are five anther pairs, but some grapevine flowers have fewer, and some have more. If the stamen is missing or poorly formed, the flower is considered female.

Check the flowers for a pistil, the female reproductive part. The pistil has three individual parts: a stigma, style and ovary. The style is the tube-like structure in the flower's center. It holds up the stigma, which has a sticky surface at its top that captures pollen from other flowers. The pollen travels down the tube to the ovary, which houses the ovules, or eggs. When a sperm cell in the pollen tube unites with an egg cell in the ovary, an embryo plant is produced, and the ovary enlarges to become a grape. If the pistil is missing or poorly formed, with only a small ovary, the flower is considered male.

Bring a sample of the grapevine to a local nursery or cooperative extension office to find out whether it is a cultivated varietal or a wild one. This will provide you with additional information on what you've concluded about your flowers. There are many wild vines that feature well-formed female parts, along with poorly developed anthers and filaments. These require nearby male or hermaphroditic vines in order to produce fruit.