Flowering and Fruit Characteristics of Black Walnuts: A Tool for Identifying and Selecting Cultivars

Compare the nuts of walnut cultivars side by side

                                                                                       

                                                                                       

Growth characteristics of selected black walnut cultivars

*Davidson cultivar is not pictured.

Characteristics definitions

• Fingerprint alias
  Some cultivars with different names are genetically identical as determined by DNA fingerprinting. Where this occurs among the cultivars listed in the table, "cultivar name" is the name thought to have been assigned first; "fingerprint alias," later.
• Budbreak
  The average date of budbreak is the time when the tips of leaves are visible from swollen buds. Female or pistillate flowers develop at the tips of the new growth, while male or staminate flowers are produced on catkins on one-year-old growth.
• Pistillate bloom dates
  Pistillate bloom occurs over a period of several days. Thus, date of first pistillate bloom is important in selecting cultivars that will avoid injury due to late-season frosts. The mean (average) pistillate bloom date is when female flowers are most likely to be receptive to pollen.
• First pollen shed
  Mean dates of pollen shed are important because these dates must coincide with pistillate bloom and receptivity for effective cross-pollination and subsequent fertilization to occur.
• Flower type
  Black walnut cultivars exhibit two flowering habits. Protogynous cultivars are those that produce pistillate flowers before the staminate flowers. Protandrous cultivars produce staminate flowers on catkins before the pistillate flowers are visible.
• Season length
  Season length is the number of days from the mean pistillate bloom date to the date of harvest.
• Harvest date
  Average date of harvest is the date by which nuts are suitable for harvest.