City Creek Nature Notes – Salt Lake City

July 11, 2017

July 5th

Filed under: Gambel's Oak, Weather — canopus56 @ 3:46 am

Some Mornings You Get Up and Find that Everything You Thought You Knew is Wrong

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Range of Gambel’s oak leave shapes collected along City Creek Canyon Road. (Author taken July 2017).

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Cottam’s F2 Cross of Gambel’s F1 hybrid oaks leaves, 1982. (Figure 2 in Cottam, Tucker and Santamour 1982).

3:00 p.m. It reaches a record-breaking 104 degrees Fahrenheit in the city today, and as I jog up the canyon, I collect samples of Gambel’s oak leaves. The heat as driven everyone except a few bicyclists from the canyon. Restoring solitude prevails. At the three communities of birds near the Gate, mile 0.6, and milepost 1.0, only two birds each can muster the energy to sing. Near mile 0.4 (Lat. 40.8003234722222, Long. -111.872787472222) is a grove of Gambel’s oaks that I find unsettling. I have long been confused by what a Gambel’s oak is. Almost no Gambel’s oak leaves that I have seen in the Wasatch Front Mountain Range or in City Creek Canyon match the picture in my tree field guide (National Audubon Society 2008 at Plate 246). This oak grove at mile 0.4 is unlike all the other Gambel’s oaks in the canyon. It has the deep lobes and pointed ends that match my field guide. This grove is the only “pure” Gambel’s oak (Quercus gambelii Nutt.) in the canyon, and its trees are unique. Unlike the stunted growth of most oaks with twisted trunks, which only reach at most 12 feet in height, the trees in this grove reach thirty or forty feet and their trunks are straight.

At home, I arrange my gathered leaves into a grid. Down the left-side are samples of these “pure” Gambel’s oak leaves. To the right of these and proceeding to the right side of the grid, the oak leaves increase in lobe roundness. Towards the bottom of the grid, the leaves decrease in lobe ratio – the lobes disappear towards the bottom of the row. This examples only describe the range of Gambel’s oak leaves found in the canyon. I have not collected a large sample and measured each leaf’s lobe ratio (July 4th) in order find the statistical median of leaf shapes. The historical re-enactor at “This is the Place Monument” was right (July 3rd). The oak forest surrounding the Salt Lake Valley and in the canyon are all hybrids – but they are second generation F2 crosses (July 3rd and July 4th). Conversely, I was also right – I could find no Cottam F1 hybrids at “This is the Place” monument (id). The canyon is covered in a example of plants adapting to an extreme ancient climate change.

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Per Thoreau’s “Journal” on July 5th, 1852, he notes as a sign of the seasons, that plants bear ripening fruit. He see cherry birds. He describes a sunset where cloud banks stripe the horizon. On July 5th, 1854, he smells blue-curls and life-everlasting flowers.

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No scientific journal expressly describes the Gambel’s oak forest surrounding the Salt Lake Valley as consisting mostly of Cottam’s F2 hybrids. The Utah Native Plant Society’s Frates suggests that is the consensus opinion of most botanists (Personal communication, July 2017). But the essential correctness of this opinion can be seen in Figure 2 of Cottam, Tucker and Santamour’s 1982 “Oak Hybridization at the University of Utah”. In that figure, Cottam arranges his F2 hybrids along a spectrum from those resembling Quercus turbinnell Greene on the top row. Those F2 leaves in the bottom four rows resemble the typical Gambel’s oak leaves seen along the Wasatch Front Mountain Range.

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On July 5th, 1907, 40,000 to 50,000 City residents spent the holiday at various resort locations including City Creek Canyon (Salt Lake Tribune, Intermountain Republican). Tragically, three-year old Ellen May Elte drowned in City Creek (id).


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