Aquilegia coerulea

Aquilegia coerulea, the Colorado columbine, Rocky Mountain columbine, or blue columbine, is a species of flowering plant in the buttercup family Ranunculaceae, native to the Rocky Mountains and some of the surrounding states of the western United States. It is the state flower of Colorado. The Latin specific name coerulea (or caerulea) means "sky blue".

Description
Aquilegia coerulea is a herbaceous plant with flowering stems that may be 15–80 cm when fully grown. Its leaves are on stems that are always shorter than the flowering stems, just 9–37 cm and are compound leaves that usually have three leaflets on three components (biternate), but occasionally may be simpler with just three leaflets (trifoliate) or more complex (tripinnate). Each leaflet is quite thin, smooth and hairless on the upper side, and green. They may either be glabrous or covered in fine, minute hairs on the underside of the leaf and have three. Leaflets most often range in size from 13–42 mm, but occasionally may be as long as 61 mm.

The plant flower buds nod, facing somewhat downward. The flowers are large and showy with a diameter of as much as 15 cm, but more often about 5–10 cm. They are so striking that the botanists E. O. Wooton and Paul C. Standley enthusiastically wrote of them in their 1915 Flora of New Mexico, "'This is the State flower of Colorado and no other State has one so beautiful. Few indeed are the flowers of the Rockies that can compare with this in beauty. The great blossoms, sometimes six inches in diameter, look like bits of fallen sky, and when the plants cover acres of meadow, as they sometimes do, no words can be found to do them justice.'" The flowers are atop stems that stand perpendicular to the ground with the outer five sepals in shades of white to deep-blue or occasionally pink in their wild condition. The sepals range in shape from a flattened circle with somewhat pointed ends with the widest part moved toward the base (-) to like a somewhat egg shaped spear head (-ovate}. They range in size from 26–51 millimeters long and 8–23 millimeters wide.

The five petals have very long tapered spurs, ranging from 25–72 millimeters in length, though usually longer than 34 mm. The blades of the petals are 13–28 mm long by 5–14 mm wide. Petals are most often white to cream in color at the front with the spurs the same color as the sepals.

The center of the flower has a projecting cluster of numerous bright orange-yellow stamens, 50–130 total. The stamens range in length from 13 to 24 mm. They surround five to ten unfused carpels. If fertilized each of the carpels may develop into a dry pod that splits along one side (a ). Each of the pods is round in cross section and is filled with small, smooth, black seeds.

The leaves may be mistaken for that of a meadowrue (Thalictrum), but the flowers are entirely different and the species cannot be confused while flowering. Similar columbines in its range include Aquilegia scopulorum, Aquilegia jonesii, and Aquilegia micrantha. Aquilegia scopulorum has leaves that are covered in natural waxes making them blue-green rather than green. It is found in Nevada and Utah. Aquilegia jonesii has much shorter spurs on its flowers, just 8-15 mm and grows to the north in Wyoming, Montana, and Alberta. Aquilegia micrantha has very sticky leaves.

Taxonomy
The first scientific description of Aquilegia coerulea was by the American scientist Edwin James in 1822. Though Aquilegia coerulea was the original spelling by James, it has often been spelled as Aquilegia caerulea as this is more correct Latin. However, the rules of taxonomic nomenclature generally prefer the original spelling and this is the name adopted by the Board of International Botanic Nomenclature. James found the first specimen he collected in a thicket of scrub oak near what is today Palmer Lake, Colorado while on the Stephen H. Long Expedition of 1820. After James's description seven species, six subspecies, five varieties, and two botanical forms have been described that are considered to be synonyms of the species or one of its four varieties.

Sequencing of the genome of this species has advanced the study of the evolution of basal eudicots.

Varieties
There are four widely accepted varieties of Aquilegia coerulea according to Plants of the World Online, World Flora Online, and World Plants. Though World Plants additionally lists Aquilegia coerulea var. daileyae Eastw. as valid as does the USDA Natural Resources Conservation Service PLANTS database.

Aquilegia coerulea var. alpina
This variety was scientifically described by the botanist Aven Nelson in 1896. It is known by the common name of Colorado alpine columbine. Though botanical writers such as Robert Nold doubt the validity of the variety. It differs from the other varieties by having much smaller petal blades, only 13–17 millimeters instead of 19–28 millimeters. It grows on open rocky slopes in the state of Wyoming at elevations of 2100-3500 m. It always has pale blue sepals and flowers from June to August. NatureServe has not evaluated the variety since 2001, but at that time they listed it as "vulnerable" (T3), but they also list it as possibly extirpated from Wyoming and with an unevaluated status in Utah.

Aquilegia coerulea var. coerulea
Five species were described at various times that are considered heterotypic synonyms of this variety. The autonymic variety of the species grows in Wyoming, New Mexico, and Colorado at elevations of 2100-3500 m. It is distinguished from the two following varieties by having medium to deep blue sepals where they have white, pale blue, or pink sepals. It's sepals range in length from 28–43 millimeters. The petals have spurs that are 34-48 mm long while their blades are usually 20–24 mm, though occasionally as short as 17 mm. They grow on rocky slopes, near streams, in open woodlands, and in herb dominated meadows. They flower in the summer starting in mid-June and may flower as late as early September. NatureServe evaluated the variety in 2004 and found it to be "apparently secure" (T4) globally and in Wyoming. They did not evaluate the rest of its range.

Aquilegia coerulea var. daileyae
This disputed variety was described by the botanist Alice Eastwood in 1897. It is a variation where the petals lack spurs and both the petals and spurs are colored deep blue and commonly called spurless columbine, but is also sometimes called Dailey's columbine. The spurless columbine may be found in identical habitats to var. coerulea, but only in the state of Colorado. From the foothills to alpine areas forest openings. Colorado resident Anna Dailey collected specimens of the spurless columbine near Evergreen, Colorado and sent them to Eastwood. A genetic mutation causes the petals to be replaced with a second set of sepals. The population continues to reproduce in and near the Reynolds Park open space in Jefferson County, Colorado. They are also found around Estes Park, Colorado near Rocky Mountain National Park. Though lacking parts to produce nectar the flowers are still polinated by bumblebees, which collect pollen from the plants.

Aquilegia coerulea var. ochroleuca
William Jackson Hooker described this variety in 1864. It had previously been described as a species by Thomas Nuttall in 1834 with the name Aquilegia leptoceras. This species name was also unnecessarily reclassified as Aquilegia coerulea var. leptoceras by Aven Nelson in 1909. It was inadvertently described by Asa Gray as Aquilegia coerulea var. albiflora in 1895 from which it was reclassified by Edwin Blake Payson as a subspecies in 1918. It differs from var. coerulea by having lighter blue or white sepals (occasionally pink) and from var. pinetorum by having shorter flower spurs (usually 40–48 mm, but possibly 36–54 mm) and shorter stamens (13–18 mm). It grows in Idaho, Montana, Nevada, Utah, and Wyoming at elevations of 2000-3600 m. It flowers as early as late June and may bloom as late as August. It is commonly known as white Colorado columbine, despite the fact that it may have light blue or pink sepals. When it was evaluated by NatureServe in 2004, they assigned it the status of "aparently secure" (T4).

Aquilegia coerulea var. pinetorum
This variety was first described as a species with the name Aquilegia pinetorum in 1910 by Ivar (Frederick) Tidestrøm (1864-1956). In 1918 Edwin Blake Payson described it as subspecies of Aquilegia coerulea and in 1942 Thomas Henry Kearney and Robert Hibbs Peebles gave it the present classification as Aquilegia coerulea var. pinetorum. Like var. ochroleuca it may have white to pale blue sepals, occasionally light pink, while it has longer petal spurs (usually 50–58 mm, but ranging from 45–72 mm) and longer flower stamens (17–24 mm). This variety is found in Utah and Arizona at elevations of 1800-3400 m. They may flower starting in May or as late as September.

Names
The genus name, Aquilegia, is frequently said to mean "eagle-like". The author Bill Casselman strongly asserts this to be incorrect and that the name derives from the Latin adjective "aquilegus" with the meaning "drawing water". The species name, coerulea, is also Latin meaning "sky-blue" or "dark-blue".

Two of the most frequently used common names in English are Colorado columbine and Colorado blue columbine. However, the species is also called Rocky Mountain columbine for its wider natural range, however this name is also infrequently applied to Aquilegia saximontana. The common name columbine is suggested to be related to the Latin for "Dove" for a resemblance of five doves drinking at a fountain. Aquilegia coerulea is also known as blue columbine or simply as columbine, though Aquilegia brevistyla is occasionlly known as blue columbine and many species are casually called columbines such as Aquilegia canadensis.

In the Gosiute dialect of the Shoshoni language Aquilegia coerulea is called either pa'-wa-gúmp or pa'-o-gûm-pi as recorded by Ralph Vary Chamberlin.

Range and habitat
Colorado columbine is native to the Rocky Mountains from northern New Mexico to southern Montana. It grows in all of the mountainous western half of Colorado and Wyoming. Additionally it grows in every county of Utah, parts of Nevada, and northern Arizona. It is listed by the USDA as growing in Idaho and South Dakota, but without county level distributions. The species was reported to grow in the Caribou–Targhee National Forest in eastern Idaho in 1973.

Rocky Mountain columbine grows in mountainous areas, starting at elevations lower elevations with the Rocky Mountain variety of the Douglas-fir. They become more common at higher elevations in montane ecosystems and subalpine habitats with some growing above timberline in the alpine tundra. The lowest elevations where they grow naturally is 1800 m for Aquilegia coerulea var. pinetorum and the highest is 3600 m for Aquilegia coerulea var. coerulea in the southern Rocky Mountains. This species of columbine grows poorly in heavy soils without good drainage. However, it prefers moist areas and is very often found in quaking aspen groves. It will also grow in the open coniferous forests, meadows, and in clearings. When there is sufficent water they will thrive on rocky outcrops and slopes.

Ecology
Within its natural range Aquilegia coerulea is most often polinated by hawkmoths and bumblebees. Specific species of hawkmoth include Hyles lineata and Sphinx vashti. The bumblebees include Bombus appositus, but Bombus flavifrons visit the flowers much more frequently. Hawkmoths visit most often during the night while bumblebees only visit during daylight hours. The plants are have the highest rate of cross-fertilization between plants in areas where the number of flowers is smaller and the population of hawkmoths is highest.

The western bumblebee (Bombus occidentalis) has been observed nectar robbing from Aquilegia coerulea by opening or using holes cut in the spurs. Though prior to its decline in numbers in the 21st century they were also a significant pollinator of the species in some areas. The broad-tailed hummingbird also visits the blooms, but at a much lower rate than moths or bees.

The wildflower authors Frank and John Craighead attributed a decline in the population of the species to overgrazing by sheep and cattle in 1963.

Culture
Though it is not the standard form for a columbine, the long spurs and shape of the Colorado columbine's flower is the most recognized in the genus. The white and lavender variety of the columbine was officially instituted as the flower symbol of Colorado on 4 April 1899 by an act of the Colorado General Assembly. In 1925 the species was protected by law in Colorado, preventing needless destruction or waste of the flowers. It prohibits the digging or uprooting Colorado columbine plants on public lands and prohibits picking more than twenty-five flowers, buds, or stems in one day. In the 1890s there was also a group called the Columbine Association that sought to establish it as the national flower of the United States.

Cultivation
Aquilegia coerulea is used as an ornamental plant in gardens. The species was adoped as a garden plant very soon after its scientific description, with its introduction to the United Kingdom coming in 1864. It is also planted in American gardens for its attractiveness to hummingbirds. They are tollerant of damage by deer and rabbits. It is also recommended as an attractive plant for revegitation of mountain roadsides in its native range by the Office of Natural Environment in the Federal Highway Administration. When planting large areas it is seeded at a rate of 112 ounces per acre.

Colorado columbine is winter hardy in USDA zones 3–8. Plants in cultivation grow most successfully in average to medium garden soil that is well drained and even moisture. They may be grown by gardeners in full sun or partial shade. It is propagated both by seed and the division of plants.

Colorado columbine is vulnerable powdery mildews, particularly when its leaves are regularly wetted by overhead irrigation. It is also susceptible to infestation by aphids, though not more than other species of columbine. Plants can also be attacked by leaf-mining flies and sawflies.

The treatment of seeds with gibberellic acid and planting at 21 C results in 93% germination after three weeks. The seeds also display resistance to sprouting without treatment with none sprouting when planted at 21 °C and 40% germination after two weeks after first being cold stratified at 4.5 C. When grown in gardens plants will last three or four years a most and often are treated by gardeners like a biennial.

Its natural variability and ease of hybridization with other columbines is exploited in the selection of numerous cultivars in different shades. This is a drawback to gardeners seeking to have standard blue and white columbines, often requiring them to seek collected seeds rather than replanting. The cultivars that are probably entirely or largely derived from Rocky Mountain columbine include 'alba', 'albiflora', and 'snow queen'. Cultivars that are thought to be significatly of A. coerulea ancestry include 'crimson star' and 'rose queen'. While the 'origami mix' hybirds, origionally developed by Goldsmith Seeds, are listed by some sources as being derived from A. coerulea others list it as being from Aquilegia vulgaris.