Ten Degree Tangerine

Ten Degree Tangerine, also known as Clemyuzu 2-2, is a cold-hardy Clementine × Yuzu hybrid bred by Dr. John R. Brown. The Clemyuzu 2-2 designation appears in Brown’s breeding account, published by C. T. Kennedy in The Hardy Citrus of Texas — Part II.^⁠[2]

McKenzie Farms & Nursery’s 2023 tour labels its tree “10° Tangerine Clem Yuzu 22” (read in this catalog as ClemYuz 2-2) and reports that it survived 8°F in 2018 with damage. Nagle’s 1993 article and the 1993 Ichang handout had already used Ten-Degree Tangerine for ClemYuz 3-3; a 2014 Hardy Citrus post records confusion about whether the name also referred to 2-2. The sources document different uses, but no source establishes when or how the name came to be used for 2-2.^{⁠[7]⁠[12]⁠[11]⁠[15]}

The Hardy Citrus of Texas — Part II was written by C. T. Kennedy from the notes of Dr. John R. Brown, who bred the variety. Brown’s account describes a Clementine tree returning to bloom after the January 1961 freeze and being intentionally pollinated with Yuzu pollen. The resulting seedlings were designated ClemYuzu. Brown reported that Clemyuzu 2-2 survived approximately 5 °F (−15 °C) with only slight damage, though the tree produced no crop the following year.^⁠[2]

The recorded cross is Clementine × Yuzu, with Clementine as the seed parent and Yuzu as the pollen parent.^⁠[2]

The Clementine parent is inferred to have been Algerian Clementine. USDA Circular No. 181 (1931) records that Clementine budwood was sent to the United States by L. Trabut in Algeria in 1909 and notes plantings in southern Texas. This provides historical context for the inference.^⁠[5]

Algerian Clementine is therefore shown as an inferred parent, rather than a confirmed identification of the specific clone used in the cross. The shared fruit shape and loose, puffy peel observed in the supplied Algerian Clementine references provide additional editorial morphological support for this inferred identification; the exact parental clone remains unconfirmed.^⁠[5]⁠[9]

During a Tough Citrus tour of McKenzie Farms, Stan McKenzie describes the fruit as tasting “just like you’re eating lemonade”.^⁠[1]

Historical descriptions distinguish ClemYuz 2-2 from ClemYuz 3-3: the 1993 handout describes 2-2 as larger, blotchy yellow, coarser and earlier, while 3-3 is smaller, orange, smoother and later. In a 2018 forum comparison, eyeckr said his 2-2 ripened earlier and tasted better when fully ripe; he had grafted over his 3-3 years earlier. A 2007 forum post labels eyeckr’s fruiting Ten Degree as 3-3 and says his 2-2 had not yet fruited; a 2014 post records uncertainty about whether the common name also referred to 2-2. These source-specific observations do not establish universal name usage or a propagation link.^{⁠[11]⁠[14]⁠[13]⁠[15]}