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

Figure 1
Compare the nuts of walnut cultivars side by side.

Table 1
Growth characteristics of selected black walnut cultivars.

Cultivar name (Fingerprint alias)	Budbreak	Average first pistillate bloom date	Mean pistillate bloom date	First pollen shed date	Flower type	Season length	Harvest date
Beck	April 28	May 15	May 21	May 16	Protogynous	128 days	Sept. 25
Bowser	April 29	May 9	May 14	May 19	Protogynous	128 days	Sept. 17
Brown Nugget	April 16	April 27	May 1	May 10	Protogynous	131 days	Sept. 8
Cranz	April 29	May 19	May 21	May 11	Protandrous	130 days	Sept. 27
Crosby	2 May 2	May 10	May 19	May 20	Protogynous	142 days	Oct. 3
Davidson1	April 12	April 23	April 28	May 9	Protogynous	132 days	Sept. 4
Drake	April 28	May 6	May 13	May 15	Protogynous	151 days	Oct. 9
Elmer Myers	May 1	May 10	May 17	May 23	Protogynous	128 days	Sept. 18
Emma K	April 20	April 23	April 30	May 6	Protogynous	148 days	Sept. 23
Football	April 15	April 27	May 1	May 6	Protogynous	156 days	Sept. 30
Grundy	April 20	May 10	May 12	April 28	Protogynous	122 days	Sept. 13
Hare	April 29	May 7	May 16	May 20	Protogynous	143 days	Sept. 30
Harney	April 27	May 8	May 15	May 16	Protogynous	133 days	Sept. 26
Hay	May 5	May 14	May 22	May 24	Protogynous	135 days	Oct. 3
Higbee Mill	May 4	May 17	May 27	May 25	Protogynous	131 days	Oct. 2
Jackson	April 16	April 27	May 2	May 9	Protogynous	155 days	Sept. 28
Knuvean	April 18	May 11	May 17	April 29	Protandrous	136 days	Oct. 1
Kwik Krop	April 26	May 5	May 9	May 18	Protogynous	148 days	Oct. 3
Mintle	April 17	May 14	May 19	May 1	Protandrous	129 days	Sept. 23
Mystry	April 16	April 29	May 4	May 11	Protogynous	141 days	Sept. 19
Neel #1	May 3	May 12	May 21	May 21	Protogynous	141 days	Oct. 5
Ness	April 16	April 27	April 30	May 10	Protogynous	168 days	Oct. 12
Ogden	April 23	May 6	May 10	May 13	Protogynous	168 days	Oct. 18
Ohio	April 24	May 7	May 8	May 15	Protogynous	140 days	Sept. 18
Patterson (Emma K)	April 16	April 25	April 30	May 6	Protogynous	153 days	Sept. 28
Pound #2	April 24	May 8	May 17	May 20	Protogynous	143 days	Oct. 1
Pritchett	April 18	April 28	May 6	May 12	Protogynous	134 days	Sept. 14
Rhower (Thomas)	April 28	May 7	May 13	May 20	Protogynous	145 days	Oct. 2
Sarcoxie (Kwik Krop)	April 25	May 4	May 9	May 15	Protogynous	141 days	Sept. 25
Sauber #1	April 26	May 6	May 14	May 18	Protogynous	134 days	Sept. 20
Sauber #2 (Sparrow)		May 8	May 14	May 17	Protogynous	118 days	Sept. 5
Schessler	April 13	April 22	April 29	May 6	Protogynous	129 days	Sept. 4
Scrimger (Sparrow)	April 27	May 10	May 14	May 15	Protogynous	117 days	Sept. 5
Shreve	May 2	May 8	May 17	May 17	Protogynous	147 days	Oct. 4
South Fork	April 14	May 9	May 6	April 28	Protandrous	158 days	Oct. 8
Sparks 127	April 25	May 7	May 12	May 16	Protogynous	118 days	Sept. 4
Sparks 129	April 23	April 27	May 6	May 15	Protogynous	125 days	Sept. 28
Sparks 147	May 3	May 11	May 15	May 18	Protogynous	131 days	Sept. 21
Sparrow	April 26	May 11	May 13	May 16	Protogynous	119 days	Sept. 6
Surprise	April 25	May 6	May 10	May 15	Protogynous	143 days	Sept. 30
Thomas	May 2	May 6	May 15	May 21	Protogynous	145 days	Oct. 2
Thomas Myers	May 5	May 11	May 21	May 21	Protogynous	131 days	Sept. 26
Tomboy	April 18	April 27	May 1	May 9	Protogynous	135 days	Sept. 10
Wiard	April 28	May 14	May 24	May 9	Protandrous	125 days	Sept. 21

¹Davidson cultivar is not pictured.

Characteristics definitions in Table 1

• 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.

XM1001, new February 2008