Coming to Yosemite to watch flowers open may sound like the beginning of a joke — Did you hear the one about the guy who went to Yosemite to watch the flowers open?
And yet, when the deer are kind to us, watching the evening primroses open in our yard is one of our great pleasures of summer. The nightly show is so stunning that it was once one of the principal attractions of Yosemite, rivaling Half Dome and the giant sequoias with visitors in the early 1900s. And then, just as Yosemite became world-famous for those blooms, they were gone forever. The story of the evening primrose and how they mostly disappeared touches on a surprising range of topic from the history of the Ahwahnechee, their expulsion from Yosemite, the commercialization of the park, the history of color and motion picture photography, and ultimately humans’ relationship to nature. That’s a lot for one little flower.
Read on to learn about evening primroses.
- Part I: The Natural History of the Evening Primrose
- Why is watching a flower exciting?
- A bit about their ecology.
- Part II: Cultural History: The Rise and Fall of Evening Primroses in Yosemite
- How they came to be a major attraction in Yosemite around 1900.
- How they came to disappear.
- What the story of the evening primrose says about the human presence in Yosemite and our relationship with nature.
Part II really gets down in the weeds (bad pun, I know), but if that does not interest you, you can just look at the pictures and videos. Do not skip the video.
What’s so exciting about watching a flower blossom?
In the case of Oenothera elata, aka Hooker’s evening primrose, the yellow blossom almost the size of the palm of your hand opens most of the way in just a few seconds. When people see video of an evening primrose opening, they usually think it’s a time-lapse. On the best nights at our house, it happens over 100 times in about 40 minutes.
A few years ago, our friend Russ of Yosemite Hikes fame took this one-minute video in our yard. It will give you a sense of how fast the evening primrose opens. This real time, not a time lapse:
This shorter video is a time-lapse that shows a five blossoms opening in 15 minutes and 17 seconds, compressed into about 12 seconds.
Basic Evening Primrose Ecology
The evening primrose is a biennial. The first year it grows with just a basal cluster of leaves — no stalk and no flowers. It’s just putting out leaves and capturing as much solar energy as it can and storing that energy in its roots for the big show the next year.
That second summer, it uses the stored energy and the new energy coming in to grow as high as four feet tall and can have a few dozen blossoms. The blossoms last for only one night, coming out at sunset in order to avoid having their precious pollen and nectar taken by day-flying pollen thieves (no judgement, this is just what botanists call an insect that takes pollen and nectar without pollinating the flower). To be effective gathering and spreading the gooey, filamentous pollen strands of an evening primrose, the insect needs to be properly equipped. No insect is so well-equipped for the task as the sphinx moth, who we will meet in a moment.
These blossoms really are intended for the night flyers first and foremost — in the full heat of the summer, the blossoms will be wilted and “dead” by 11am, sometimes earlier.
The pistil, that long thread with the cross at the end (called the stigma) in the middle of the blossom, is the pollen receiver. If you pull it out, the filament is 2-3 inches long. Around it are the stamens with a sort of gooey pollen that sticks to the moths and travels with them to the next blossom. The pollen grain brushes off on the cross-shaped stigma, then travels all the way down that tube to the ovaries to fertilize the seeds. It has to complete that journey overnight before the flower wilts.
The plant then makes hundreds of seeds for every seed pod. The pods eventually dry out and open and that tall plant, blowing back and forth in the wind, ejects the seeds a fair distance, like Father O’Connor spraying the congregation with holy water.
More on the evening primrose
- Calflora database for information on distribution and such
- USDA distribution map
- Calphoto for lots of photos
Is that a bird?
Notice the supporting cast in that video. It looks almost like a hummingbird when you first see it flying, but you will soon see that it is the gorgeous White-lined Sphinx Moth (Hyles lineata).
The sphinx moth’s secret weapon is a very long proboscis that lets it reach deep into flowers that have a large nectar reward. They are known to frequent columbines and we have seen them on pennyroyal, but the evening primrose is clearly a favorite. The sphinx moth is a major evening primrose pollinator. In return, the evening primrose provides food not just for the adults who come for the nectar, but for the caterpillars as well.
Their timing is impressive. We rarely see these moths, but within minutes of the first blossom opening, they arrive. To our human noses, the smell of the evening primroses is subtle, not like the powerfully-scented flowers like azalea. Apparently for a sphinx moth, it’s like Mama Ciccardi’s famous marinara sauce cooking on the stove on a summer evening — within minutes, the smell wafting from the flowers calls them to dinner from the far corners of the neighborhood.
The sphinx moth is not the only pollinator. We see other insects in the flowers sometimes, but typically only in the morning. Carpenter bees (specifically Xylocopa tabaniformis) can be a major pollinator. The overlap in the range between the Xylocopa tabaniformis and the Oenothera elata suggests this is an ancient relationship developed through long co-evolution (Barthell and Knops). In our experience, though, it is the sphinx moth who rules the skies over and around the evening primroses when they open.
When does this happen?
In drought years and wet years, hot years and cool years, the first blossoms are always within a couple of days of Theresa’s birthday at the end of June. The show reaches its peak in early July and goes strong through most of the month and fades by early August, after which it’s just a few blossoms here and there. We’ll still get the occasional blossom into October, sometimes on plants that appear all but dead.
Where does this happen?
The evening primrose is not a rare plant, but it is a favorite food for deer. So while widespread, there are typically only a handful in Yosemite Valley that blossom each year. A century ago, that number was in the thousands, perhaps tens of thousands or even more, but those days are gone (that’s the story of Part II). To the best of our knowledge, the best places to see them are just east of Tioga Pass along Highway 120 (a terrific display there in good years) and at our house, except in those years like 2021 when the deer ravage “our” plants (they aren’t “ours” of course any more than we are theirs).
Taxonomy: a primrose by any other name
The evening primrose is not closely related to the primrose, just like the primrose is not closely related to the rose. They are three distinct flower families belonging to three separate orders. Roughly speaking, that means they share a great-grandparent. The evening primrose is actually somewhat more closely related to the rose than to the primrose. To get technical, roses (Rosaceae family) and evening primroses (Onagraceae family) both belong to the Rosids clade, while primroses (Primula family) belong to the Asterids clade.
Part II: The rise and fall of Yosemite Valley’s flowers
Today’s visitor often comes to Yosemite in hopes of seeing a bear, but very few people make the trip to Yosemite in hopes of seeing a flower open at sundown. In the early 1900s, it was the reverse. There were no bears in Yosemite Valley. When a bear did enter the Valley, most people thought it should be chased off or killed as soon as possible.
Meanwhile, they ranked wildflowers up there with El Capitan and Yosemite Falls as a must-see attraction. The wildflowers of Yosemite Valley inspired some of the earliest color photographs and the world’s first time-lapse movies of flowers. Indeed, time-lapse photography was virtually invented in Yosemite by Arthur Pillsbury, who held a photographic concession in the park from 1906 to 1922.
Among all the flowers of the park, the evening primrose was one of Pillsbury’s favorites. When he first came to Yosemite, he found entire meadows that would turn yellow as the flowers opened en masse. Our small patch on its best days sees 140 blossoms open in 40 minutes, peaking at perhaps 7-10 blossoms per minute. How big were the massive displays of Yosemite Valley, reputed to have turned entire meadows yellow? One hundred blossoms in the peak minute? Five hundred?
Wildflower Tourism at the Turn of the Twentieth Century
Wildflowers were such an integral part of the Yosemite experience that when the National Geographic Society ran an article about the park in their weekly Geographic News Bulletin (vol. 1, n. 9; 3 April 1922), they titled it, “The Park of a Thousand Flowers — Yosemite,” and noted that “Yosemite National Park is beloved especially by children because of its many flowers.”
It seems strange, in our era of video games and Red Bull athletes to think that children were drawn to Yosemite for the flowers, but apparently it was so which speaks to a different aesthetic in 1922 than in 2022.
That publication was aimed at teachers and clearly some read it. Later that year, The Western Journal of Education (vol. 82, no. 7, p. 8-9) ran an article on “Yosemite National Park for the Educators” that described Yosemite Valley in these terms, highlighting the central importance of the evening primroses (my emphasis):
Decorate these walls with titanic structures — El Capitan, Half Dome, Sentinel Rock, Cathedral Spires, Cathedral Rocks — chiseled smooth as glass in many places, then stud these walls with foaming cataracts that flash in the sun, Yosemite Falls… Bridal Veil…. Carpet the meadows with Mariposa lilies and evening primroses and other blossoms which have made Yosemite known as the “Park of a Thousand Flowers.” This is Yosemite Valley.Western Journal of Education, 1922
The “thousand flowers” referred to the thousand species of flowering plants, but writers also frequently mention the profusion of flowers on the Valley floor. In short, for the visitor of 1922, the flowers of Yosemite Valley rivaled El Capitan and Yosemite Falls in majesty in a way that is rarely the case a century later.
The Decline of the Evening Primrose
And yet, by the time these publications came out in 1922, the golden age of the Yosemite Valley flowers was over. In the Handbook of Yosemite National Park from 1921, the great botanist Willis Jepson wrote regarding the evening primroses (my emphasis):
One of the remarkable sights of the upper reaches of the Valley in midsummer are the fields of tall yellow Evening Primroses… In favorable seasons the dry open fields about Yosemite are often yellow with these stately plants. Many of the finest groups, however, are now a thing of the past, due to the mowing of the meadows for wild hay.Jepson, Handbook, p. 254
In her 1929 survey of flowers in Yosemite Valley, the naturalist Enid Michael noted that, “June of the year 1920 witnessed the last great bloom on the floor of the Valley” (Giddens and Heady, p. 25). Joseph Dixon, writing in 1934, said that in a survey of Yosemite Valley in the late 1920s, only six evening primrose plants had been found in the whole valley (Dixon, p. ?? [get page no. from copy in Yosemite Research Library]).
A few years later, the Wildflower Man of Yosemite himself, photographer Arthur Pillsbury, wrote (my emphasis):
Unhappily this Primrose is now almost extinct in the Yosemite meadows. The mowing machine took its toll and since it has been put on the protected list the deer have acquired a fondness for the leaves, not hesitating, either, at blossoms.Pillsbury, Picturing, p. 54
What was still a highlight of a Yosemite trip in 1910 had all but disappeared by the 1920s. The naturalists lamenting the loss of the evening primroses typically point to two factors: farming and deer.
Why did deer become a problem for Yosemite flowers in the 1920s? What changed? Why were there so many flowers in 1910 and why were they all but gone by 1922?
Flowers in the Valley before 1900
After the glaciers receded, Yosemite Valley was a wetland or a lake. As the lands silted up and the waters receded, there is some evidence of ancient forest in Yosemite that was wiped by either rock slides or fires, either natural or manmade (Gibbens and Heady, p. 8-9).
For at least a few thousand years, inhabitants of Yosemite Valley set fire to the meadows annually, typically in the autumn. This made it easier to harvest fallen acorns and promoted the growth of plants with edible bulbs and tubers. Many of the common flowers we know today were prized as root crops, like Elegant Brodiaea (Brodiaea elegans), Blue Dicks (Dichelostemma capitatum), Mariposa Lilies (various Calochortus species), and many more. See the wonderful article by M. Kat Anderson and Frank K. Lake on the various “geophytes” (roughly speaking, “root crops”) prized and eaten traditionally in California.
The meadows were also important for plants such as dogbane (Apocynum cannabinum). Dogbane was not an important food crop. As the name suggests, it’s poisonous at least to dogs. It was essential for making twine which could be used to make nets, traps and anything else requiring rope. It was therefore an essential material for the residents of Yosemite Valley.
The Valley was sometimes described as “swampy,” but the new guardians of the Valley brought changes. It’s likely that swampy crops like onion were common, though they are rare today. Meanwhile, those same moisture levels made the meadows inhospitable to the native pines, firs and oaks. The Ahwahnechee practice of burning the meadows was important also kept tree encroachment at bay.
It also appears that the Ahwahneechee used fire to hunt the deer in Yosemite Valley, and probably elsewhere (Ernst, p. 39). So the fire that kept the trees from overtaking the Valley also helped keep the deer population down and, therefore, prevented the deer from eating so many of the Valley’s flowers. Indeed, oral tales speak of the Ahwahneechee going up to the Valley rim to hunt for deer, presumably because deer were not sufficiently abundant on the Valley floor.
As soon as the burning stopped, the size the of the meadows started to decrease. The European-American methods of controlling the brush through cutting was far more labor intensive than burning. It was impossible to keep the overgrowth at bay and the meadows began to fill with brush and forest. A survey in 1868 found that there were 745 acres of meadow in Yosemite Valley. By 1937, only 327 acres of meadow remained (Gibbens and Heady, p. 24).
In addition, the European-Americans changed the hydrology of the Valley. Blasting the recessional moraine near El Capitan in 1878 for the express purpose of draining the Valley had a major impact on the meadows. Road building and utility pipes, often becoming cracked and abandoned, also impacted the hydrology of the Valley and accelerated the drying of the meadows (Gibbens and Heady, p. 8 and passim). With the drying came more brush, more trees, and fewer flowers.
All of these changes that came with the expulsion of the Ahwahnechee combined to create a Valley floor that had far less meadow and much more undergrowth than it had in perhaps thousands of years. Still, the 1937 state of the Valley was far less forested than what we have become accustomed to in the twenty-first century. In addition, the absence of grazing animals there, either wild or domestic, meant there was a lot less predation of those flowers that did grow. The result was undoubtedly a greater quantity of flowers than we know today, but beyond that we mostly know only about the species that were used for food, and precious little even about those.
Yosemite Valley from Invasion to National Park
After the Ahwahneechee attacked a couple of trading posts, the Mariposa Battalion invaded Yosemite Valley in 1851 and forced the Ahwahneechee out for the first time. The tribe returned that winter, but most were forced out definitively in 1852. Though a small number resided in the Valley into the 1960s, they effectively lost control of their lands and therefore the meadow burning stopped in the 1850s and the meadow drying began soon after, with the consequences we’ve just seen.
Those consequences did not, of course, happen immediately. In 1855, just four years after the initial invasion by the Mariposa Battalion, an early tourist wrote that Valley was rich with strawberries:
The wag of our party said that any man who would find three feet square in a space of six hundred acres, where we encamped, that did not have the strawberry on it, should have the pleasure of shooting through his hat. The search was made for the space; but our friend says his hat will never have a hole through it from this proposition.Reprinted in Browing, p. 219.
In 1864, Yosemite Valley became a California state park, but it was managed much less actively than today. Despite its status as a park, settlers and business people soon began grazing cattle and horses and plowing for crops. At least 20 acres of El Capitan meadow were plowed and sown with fodder for horses and cattle. Many other meadows were plowed or used as pasture for both horses and cattle. By 1887, 150 acres of Stoneman Meadow was under active cultivation. People began to complain and in 1890 new rules were passed to reduce farming in Yosemite Valley. Nevertheless, the government plowed and planted Ahwahnee Meadow from 1910 to 1914. Other meadows were not plowed, but they were mowed for “wild hay” as late as 1924 (Gibbens and Heady, pp. 4, 21-22).
Despite this history of plowing and mowing, Yosemite Valley nevertheless had breathtaking displays of flowers, with the evening primrose as one of the stars, perhaps the star of the show. How is it, then, that the evening primroses thrived in the presence of mowing, and yet disappeared about the time mowing stopped?
Naturalists of the time point to two factors. First, before the mowing ended, it moved to new locations and wiped out some of the best surviving collections of flowers. Second, the deer population boomed. By the time the plowing and mowing stopped, the number of deer was sufficient, as it is now, to all but eliminate the evening primrose from the valley.
Yosemite Valley: Death Trap to Animals
(Or: Why the Deer Didn’t Eat All the Flowers in 1900)
We think of deer as numerous and ubiquitous in Yosemite Valley, but it wasn’t always the case. As we saw in the discussion of Ahwahnechee practices, deer had probably been rare on the Valley floor for hundred, perhaps thousands of years. With the influx of settlers and their guns in substantial numbers, along with most large animals, were hunted to extinction on the Valley floor.
Though the national park had been created in 1890, Yosemite Valley remained a state park under state management. Rules against hunting were widely ignored. In 1905, Yosemite Valley became part of Yosemite National Park. The next year, the U.S. Army, who managed the larger national park, took over management of Yosemite Valley as well. In his 1906 report, Acting Superintendent Major Harry Benson reported to Washington about the conditions he found on taking charge of the Valley (my emphasis):
The Yosemite Valley itself has, during recent years, been a death trap to all game that was unfortunate enough to enter it. Practically every person living in the valley kept a rifle, shotgun, and revolver, and any animal or bird that was unfortunate enough to enter the valley was immediately pursued by the entire contingent, and either captured or killed. A bear pen constructed about three years ago was found by me within 400 yards of the Sentinel Hotel.
During the early part of September two bears entered the valley, causing great consternation among those people who had been living here for some time, and they all seemed to think that these bears should at once be pursued and driven out.Benson, Report, p. 10.
To make matters worse, during those years, the army only managed the park from May through October. The rest of the year, only two rangers oversaw the entire park. Benson noted that, as the two rangers did little patrolling, “the game scarcely receives any protection from them.”
Those conditions were terrible for the deer, but marvelous for flowers. The valley floor was reputed to be white with camas lily in the early season and yellow with evening primrose in July. It was during this period that Arthur Pillsbury took his famous hand-tinted photos of evening primroses and, later, his time-lapse movies of them opening.
As late as 1908, Acting Superintendent Benson was still worried about the low deer population and intensive hunting. But from 1909 on, the annual reports of the Acting Superintendents repeated every year that the deer population was increasing. This hurt, above all, the evening primroses. As we have found in our yard, the deer seem to love this plant as much as we do. Of course, the process took time. In his 1910 book, The Yosemite Valley, Galen Clark still noted that the evening primrose was “very common in Yosemite.”
After about 1910, the evening primroses faced greater pressure from both deer and mowing. Initially, the rise of the automobile reduced the need to grow hay and graze the meadows as there was no longer a need to feed and stable the horses that brought tourists to Yosemite (Gibbens and Heady, p. 5). At the same time, the burgeoning tourist trade in Yosemite required fresh milk and meat. In the days before refrigerator trucks, fresh milk and meat required local cattle (and a slaughterhouse, from which Slaughterhouse Meadow in Yosemite Valley gets its name). And local cattle needed hay.
Despite the predations of the plowman and the deer, however, the flower remained an attraction. The July 31, 1922, issue of Yosemite Nature Notes still suggested that visitors go out into the meadows to watch the evening primroses open.
Sounding the Alarm in the 1920s
By the 1920s naturalists in the park had sounded the alarm: the flowers were disappearing. In response, the park service and the concessioner made various attempts to hold onto the tradition of Yosemite’s great flower displays. In the early 1920s, Yosemite’s Curry Company tried to plant wildflower gardens in Curry Village with poor results: “Although plants commonly grazed by deer were avoided, the project was abandoned after three years of unsuccessful attempts to keep out the deer.” (McLelland, Chapter 4, section “Grounds of the Concessionaires”).
During the planning of the Ahwahnee Hotel, a 1927 memo called for a “plant refuge” around the hotel because, “It is well remembered that the meadows many years ago were filled with evening primroses” and other plants (McClelland, Chapter IV, my emphasis). Note that already in 1927, people thought of the spectacular blooms as something that happened “many years ago.”
After a rough start, the plants were fenced in to protect them from deer and elk, the latter having been introduced into Yosemite. In 1929, Horace Albright, the new director of the National Park Service, commented that the Ahwahnee plant refuge was “‘the only place in the valley where native flowers’ could ‘be seen in any profusion’” (ibid.). Around 2010, as I was relating some of this history to long-time ranger Bob Roney, it sparked a memory. He told me that the evening primroses were still there in the early 1970s and, though he didn’t know the history, he remembered watching them open from a seat by the window in the Ahwahnee Dining Room the night he proposed to his wife.
Meanwhile, the park service began maintaining flower exhibits behind the new museum, first with cut flowers gathered from around the park and, beginning in 1929, with a live garden protected from deer. The garden expanded under the direction of naturalist-ranger Enid Michael. In 1935, the curators planted evening primrose. This collection of now-uncommon flowers “became the object of popular evening walks” (McClelland, Chapter IV and Chapter VI).
During my ranger days, I would occasionally encounter long-time park visitors who remembered going to the museum garden in the evening to see the evening primroses open. In 1941, Enid Michael wrote an article for Yosemite Nature Notes (vol. XX, no. 4, p. 30-31) on the “Guests of the Evening Primroses,” about the carpenter bees and sphinx moths. She still waxed poetic about the show the flowers put on as the sun went down, but she located that show in the Museum Garden, not in the meadows of Yosemite Valley as the author of the 1922 article had done.
Evening Primroses Today
Over time, even the Museum Garden and the Ahwahnee Hotel “plant refuge” disappeared. Now, only visitors with a sharp eye and good timing will find evening primrose blooming in Yosemite Valley. Every year there is at least one place in the disturbed soil along the roads in the Valley that you can find an evening primrose that has survived the deer. By far the best collection grows along the road just east of Tioga Pass. It is perhaps the last place where, on a good night, you can see hundreds of plants produce perhaps 1000 blossoms. The next best place is our house in a year when we succeed in keeping the deer away.
Humans, Nature and Evening Primroses
The story of the evening primrose in Yosemite raises some interesting questions about “natural” places and whether there is such a thing or, more precisely, whether there is a real difference between “natural” places and other places.
When I first came to Yosemite in 1985, I imagined I was walking through a landscape preserved through visionary action from time immemorial just as it always had been so I could appreciate it in its natural, almost primordial form. The naivete of that young rock climber shocks me now, but both the rock climber and the culture around him have evolved somewhat in the intervening forty years.
Of course, even the most superficial reflection reveals my naive first impression to be untrue — a landscape formed by the Big Bang, plate tectonics and glaciers has no “original” form outside the Singularity. A slightly deeper reflection would have highlighted the obvious fact that there were virtually no uninhabited places in America in 1450 and still less so in 1850, so there was no primordial, untouched place to preserve in 1864. Still, I imagined that it had changed little over the last few hundred years, setting aside the accoutrements of industrial tourism such as roads, trails, hotels, vacation rentals and rangers.
The understanding that the place I thought of as stable could have changed so much in 150 years took years to appreciate. The hotels were obvious as was the absence of Ahwahnechee hunters. Only over time and with increasing knowledge of natural history, though, did I come to see that large patches of the Valley are almost entirely populated with cheatgrass (Bromus tectorum), which did not even exist in North America until the late 1800s. The common mullein (Verbascum thapsus), which grows widely throughout the Valley, was brought over by Europeans and planted as a medicinal (for stomach ailments). And many of the Valley meadows are full of Kentucky Bluegrass which, despite it’s name, is a Eurasian species, not a native of Kentucky let alone the Sierra Nevada. A century of fire suppression has radically changed the composition of our forests. They are far denser than before and biased toward small, shade-tolerant trees rather than the massive fire-tolerant (even fire loving) trees of the past.
All of that poses an obvious question: what do we mean when we talk about “natural” landscapes and going into the outdoors to experience “nature?” Is Yosemite today, with its roads, hotels, restaurants, exotic Eurasian plants, dense cedar and fir forests, and huge deer population, natural? Was the Yosemite of 1906, with no deer, plowed meadows and a magnificent show of evening primroses in unplowed areas, natural? Was the Yosemite of 1800, with double the meadow and a tiny fraction of the undergrowth that we know today thanks to annual fires set by the Ahwahneechee, natural? Was the marshy valley of 5000 years ago, before the arrival of people, ipso facto more natural than the dry valley that humans lived in? Do humans, by our very presence render a place less natural? It is now clear in the Anthropocene that there is no landscape that has not been influenced by humans, so how do we distinguish between a place like Yosemite Valley and a place like Manhattan?
Once you ask these questions, it becomes clear that simple words like “natural” and “wild” are inexact labels for slippery concepts. Better minds than mine have devoted entire books and careers to wrestling with those questions. Rather than hazarding an answer, I will end with a quote from historian William Cronon:
If wilderness can do this—if it can help us perceive and respect a nature we had forgotten to recognize as natural—then it will become part of the solution to our environmental dilemmas rather than part of the problem. This will only happen, however, if we abandon the dualism that sees the tree in the garden as artificial—completely fallen and unnatural—and the tree in the wilderness as natural—completely pristine and wild. Both trees in some ultimate sense are wild; both in a practical sense now depend on our management and care. We are responsible for both, even though we can claim credit for neither.Cronon, The Trouble with Wilderness
And that is why I have avoided calling the evening primroses that grow near our house “our plants.” We feel responsible for them, but we cannot claim credit. They are their own plants.
Many sources are either cited in full or linked in the text. The sources that are mentioned just by author name are here given in full:
- Anderson, M. Kat and Frank K. Lake. “Beauty, Bounty, and Biodiversity: The Story of California Indians’ Relationship with Edible Native Geophytes,” Fremontia, vol. 44, no. 3, December 2016, pp. 44-51.
- Barthell, John F. and Johannes M. H. Knops. “Visitation of Evening Primrose by Carpenter Bees: Evidence of a ‘Mixed’ Pollination Syndrome,” The Southwestern Naturalist, Vol. 42, No. 1 (Mar., 1997), pp. 86-93.
- Benson, Harry C. The Report of the Acting Superintendent of Yosemite National Park to the Secretary of the Interior, 1906 (Washington: Government Printing Office, 1906). For other reports (1908, 1909, etc), it’s a simple matter of looking to the subsection “Game” for the acting superintendent’s comments on the deer population.
- Clark, Galen. The Yosemite Valley, “Flowering Plants in Yosemite,” (1910).
- Cronon, William. “The Trouble with Wilderness; or, Getting Back to the Wrong Nature,” in William Cronon, ed., Uncommon Ground: Rethinking the Human Place in Nature, New York: W. W. Norton & Co., 1995, 69-90.
- Dixon, Joseph S. A Study of the Life History and Food Habits of Mule Deer in California, a reprint from California Fish and Game, vol. 20, nos. 3 and 4 (July and October 1934).
- Ernst, Emil F. “Vanishing Meadows of Yosemite Valley,” Yosemite Nature Notes, vol. XXVIII, no. 5 (May 1949)
- Gibbens, Robert P. and Harold F. Heady. The Influence of Modern Man on the Vegetation of Yosemite Valley (University of California, Division of Agricultural Sciences, July, 1964).
- Jepson, Willis Linn. “Flowers of Yosemite National Park,” p. 254, in the Handbook of Yosemite National Park, edited by Ansel F. Hall (Putnam’s, 1921).
- Pillsbury, Arthur C. Picturing Miracles of Plant and Animal Life (Philadelphia: J. B. Lippincott Press, 1937).
- McClelland, Linda Flint. Presenting Nature: The Historic Landscape Design of the National Park Service, 1916 to 1942 (National Park Service, 1993).