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Plants Collected and Described to Science from the Eastern Plains of Colorado on the Long Expedition of 1820

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Two-hundred years ago, during the spring of 1820, 22 men of the Stephen H. Long Expedition headed west from Engineer Cantonment, which is just north of present-day Omaha, Nebraska. They were bound for the high plains and the Front Range of present-day Colorado. Their goals were ambitious and included exploring and documenting some of the vast land acquired via the Louisiana Purchase of 1803. The group also included scientists trained in the European tradition, and their goal was to study the natural history of the area. One of these scientists was Edwin James, who doubled as the expedition’s physician and botanist.

From June 27 through July 27, the Long Expedition traveled through present-day Colorado, crossing lands ancestrally belonging to the Cheyenne, Arapaho, Eastern Shoshone, Ute, Pawnee, Jicarilla Apache, Pueblo, Comanche, Kiowa, Osage, and Pawnee tribes. Entering near Julesburg, the men followed the South Platte River southwest through the plains. Until their first view of the Rocky Mountains and Longs Peak on June 30, there were few notable landmarks other than the occasional bluff, various creeks and islands in the channels of the river.

On July 6, after their 10-day journey through the hot and dry plains of Colorado, the expedition reached the foothills of the southern Rocky Mountains. Here, the group encountered many iconic landmarks including Waterton Canyon, the hogbacks near Roxborough State Park, Elephant Rock, Dawson Butte and a view of Pikes Peak.

A week later, on July 14, 1820, Edwin James and two other men summited Pikes Peak, thus becoming the first Americans of European descent to have done so. This was both literally and metaphorically the high point of the Long Expedition of 1820.

The group continued south, and near present-day Pueblo Reservoir, the party connected to the Arkansas River. After several members of the party took an arduous excursion to the Royal Gorge, the expedition was on its way again. The men followed the Arkansas River into southeastern Colorado, where they descended into the Purgatoire, Chacuaco, and Bachicha Canyons. After a grueling journey through the canyon bottoms the party ascended to the high plains and soon reached the Colorado and New Mexico border.

On September 13 the party arrived at Fort Smith, Arkansas, having completed the expedition. James carried with him around 700 plant specimens, well over 100 of which were previously unknown to science (Goodman and Lawson, 244). Many of these were collected in what would become Colorado.

This tour is one of three and focuses on plant species that were collected (or were likely collected) in the eastern plains of Colorado and that were scientifically recorded on the 1820 expedition. Many of these species are part of the collections at the York Street location of Denver Botanic Gardens.

Those absent from the Gardens’ collections (from the eastern plains portion of the trip) include Quincula lobata (purple ground cherry), Baccharis salicina (Great Plains false willow), Dalea formosa (featherplume), Dalea jamesii (James’ prairie clover), Palafoxia sphacelata (desert palafox), Pomaria jamesii (James holdback), and Paronychia jamesii (James’ nailwort).


Ackerfield, Jennifer. Flora of Colorado. (Fort Worth: BRIT Press, 2017).

Goodman, G. J., & Lawson, C. A. (1995). Retracing Major Stephen H. Long's 1820 expedition: the itinerary and botany. University of Oklahoma Press.

Argemone polyanthemos (Prickly Poppy)

Bloom time: June-August; In the sandhills of Nebraska, James encountered a plant with showy, ruffled, white flowers. He noted that it was “[p]robably an undescribed species” and referred to it as Argemone mexicana, but later described it as A. alba (265). The nomenclature of what was collected is mired in confusion, but ultimately A. alba became a synonym of Argemone polyanthemos. A common species of sandy soil and dry grasslands, this charismatic species was likely in bloom along the expedition’s route through northeastern Colorado and into the Front Range.

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Artemisia filifolia (Sand Sage)

Bloom time: July-September; The location of this type collection (a specimen designated as the basis for a taxon's name) is unknown, but this species is “common in sandy places and on open, dry slopes” (Ackerfield, 121) on the eastern plains of Colorado. Look for a densely hairy sage with nodding flower heads.

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Berlandiera lyrata (Green-Eyes)

Bloom time: May-August; No locality for this collection was given. However, this species, with its long-blooming yellow ray flowers, is “common on dry, rocky limestone soil of the southeastern plains” of Colorado (Ackerfield, 125) and would have been in bloom as the expedition passed through. You may smell the chocolate-y fragrance of the flowers before you see the plant itself.

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Calylophus lavandulifolius (Lavanderleaf Sundrops)

Bloom time: May-August; Based on a description in James’ diary, authors Goodman and Lawson speculate that the type of this species was collected June 27th between Julesburg and Crook. Look for plants with sunny yellow flowers and lavender-colored leaves.

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Celtis reticulata (Netleaf Hackberry)

James also described a “Prunus” with “leaves alternate obliquely cordate” and peduncles axillary solitary one flowered” (qtd. 319). This species was in fact Celtis reticulata, a somewhat scraggly deciduous tree still found on the rocky slopes and canyon bottoms of southeastern Colorado. The foliage of this tree is often infected with insect galls, which are considered relatively harmless to the tree.

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Eriogonum jamesii (James' Wild Buckwheat)

Bloom time: June-October; This species could have been collected on July 26th in Bachicha Canyon, which is a remote canyon in Las Animas County. In the wild, James’ buckwheat is often found in pinyon-juniper woodlands and on rocky or shale slopes (Ackerfield, 688). Look for a mat-forming plant with cream or pinkish flowers.

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Eriogonum tenellum (Tall Buckwheat)

Bloom time: May-August; This species could have been collected on July 26th in Bachicha Canyon, which is a remote canyon in Las Animas County. This buckwheat has white to pinkish flowers and is found in dry grasslands and rocky open areas in the southeastern corner of the state.

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Frankenia jamesii (James' Seaheath)

Bloom time: May-July; Based on the known distribution of this species and where the expedition’s route overlap, Goodman and Lawson contend that James collected F. jamesii along the Arkansas River somewhere between Canon City and Rocky Ford (197). The only member of the seaheath family represented in Colorado, F. jamesii is a small salt-tolerant shrub with linear, revolute (rolled backward or downward) leaves and white flowers and is found in limestone, gypsum, and shale slopes (Ackerfield, 486) in the southeastern plains of Colorado, parts of New Mexico, and western Texas.

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Gaillardia pinnatifida (Red Dome Blanket Flower)

Bloom time: May-August; No locality for this collection was given, however red dome blanketflower is common in southeastern Colorado. Look for a plant with sunny-yellow ray flowers surrounding reddish-brown disk flowers growing in full sun.

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Ipomoea leptophylla (Bush Morning Glory)

Bloom time: June-August; A shrubby morning glory with numerous bright pink to purplish-red flowers, Ipomoea leptophylla is common in the sandy soils of the eastern plains. According to Torrey, James collected “[i]mperfect specimens of this plant [...] in Long’s expedition, but they were not described in my account of his plants” (qtd. in Goodman and Lawson, 179). Instead, this species was officially described to science much later from John C. Fremont's expedition.

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Linanthus pungens (Granite Gilia)

Bloom time: May-August; A shrub with linear leaves and small creamy to yellowish flowers, this phlox is common in Colorado’s dry grasslands, meadows, and open forests where it would have been in bloom in late June or early July. The location given was “Valley of the Loup Fork?” (Nebraska), which Goodman and Lawson question since the section of the Loup River which the expedition traveled is far out of the range of L. pungens. Instead they speculate that the specimen was collected along the South Platte River, anywhere from Fort Morgan to Denver (p. 272).

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Mirabilis multiflora var. glandulosa (Desert Four O'Clock)

Bloom time: June-September; This species was described by Torrey under the name Oxybaphus multiflorus. It was likely collected in Pueblo County or less likely in Otero or Las Animas Counties or New Mexico (254) in late July or early August. This species has showy pink to magenta flowers that open in the afternoon. It has become more commonly used in dry western landscapes and attracts both butterflies and hummingbirds.

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Phyla cuneifolia (Wedge-Leaf Frog Fruit)

Bloom time: June-September; This unique-looking species from the verbena family has wedge-shaped leaves with toothed margins and globose inflorescences of pinkish-white flowers. Although no location information is given, the type collection (Zapania cuneifolia) could have been made in any of the five states along the expedition’s route. However, the species was likely in bloom in riparian corridors and in open prairies when Long’s party traveled from the Colorado border south towards the Front Range.

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Pleuraphis jamesii (James' Galleta)

Bloom time: May-August; Listed in James’ diary is a grass “having spikelets involucured with a tuft of down” (qtd. 206). Torrey described this species under the name Pleuraphis Jamesii. The herbarium sheet (NYBG) lists a vague location: “On the high plains of the Trap Formation at the sources of the Canadian River” (qtd. 206). Authors Goodman and Lawson speculate that it was collected in present-day Otero County, several miles southeast of where the party crossed Timpas Creek (206).

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Populus angustifolia (Narrowleaf Cottonwood)

On July 4th, 1820, after hiking 17 miles, the party stopped mid-morning on the South Platte River. The men set up camp near the north end of Henderson Island, which is several miles south of present-day Brighton (Goodman & Lawson, p. 299). Along with Independence Day festivities (these included eating corn and drinking whiskey), James managed to botanize in the area and likely collected the holotype (an example on which the species was formally described) for Populus angustifolia (299). This species is common in riparian areas in central and western Colorado.


Ratibida tagetes (Short Ray Prairie Coneflower)

Bloom time: June-October; James would have collected the type specimen of this species when the party traveled approximately four and a half miles south of present-day Rocky Ford (Goodman and Lawson, 173). In his diary entry for the 24th, James described this as a new species of Rudbeckia.

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Sporobolus airoides (Alkali Sacaton)

Bloom time: June-September; No locality information is given. This species could have been collected anywhere from Elephant Rock on July 10th to Bachicha Canyon in Las Animas County on July 27th (Goodman and Lawson, 210). It is “common in grasslands, shortgrass prairie, shrublands, and on alkaline flats throughout the state" (Ackerfield, 664).

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