Delphinium robustum
Author: Rydb.

Wahatoya Creek larkspur

Ranunculaceae (Buttercup Family)

Close up of Delphinium robustum by Jon Stewart; used with permission from
Click image to enlarge.

Close up of Delphinium robustum by Jon Stewart; used with permission from
Click image to enlarge.

Taxonomic Comments

Weber and Wittmann place the genus Delphinium in the Helleboraceae (Hellebore Family). There is some taxonomic uncertainly with D. robustum and how it is, or is not distinct from D. ramosum. Ackerfield (2012) does not recognize D. robustum as a separate species, but places it within D. ramosum.

Ranks and Status

Global rank: G2G3
State rank: S2?
Federal protection status: None
State protection status: None

[+] Description and Phenology

Delphinium robustum: artwork forthcoming

General description: Perennial herb 1-2 m tall; stems glabrous or puberulent, sometimes reddish at the base; leaves all on stem and withered from the basal 1/5 of the stem at the time of anthesis, petioles 7-13 cm long, blades 10-20 cm long and 7-12 cm wide, palmately divided into 5 main lobes, each lobe further dissected into additional lobes or teeth that are rounded at the apex or acute with a blunt tooth (mucro); inflorescence of racemes that are paniculately branched at the base in larger specimens, 40- to 100-flowered, branches and pedicels with short hairs; sepals ovate-acute, bluish purple or pale lavender, rarely pink, sparsely pubescent, lateral sepals forward pointing, 9-14 mm long, the upper sepal extended basally into a spur 9-13 mm long; petal blades hairy, cleft, 5-7 mm long (New Mexico Rare Plant Technical Council 1999). Plants in Colorado have been observed to be 3 m or more tall (Colorado Natural Heritage Program 2012).

Look Alikes: Delphinium ramosum is typically a shorter plant with pubescent lower stems and unbranched racemes (New Mexico Rare Plant Technical Council 1999).

Phenology: Flowers July to August (Colorado Natural Heritage Program 2012).

[+] Habitat

Habitat of Delphinium robustum: not available

In Colorado, this species grows in broad canyon bottoms, along edges of meadows or in open woods. Found in sandy soil, on northwest slopes.

Elevation Range: 7,000 - 8,500 feet (2,134 - 2,591 meters)

[+] Distribution

Distribution of Delphinium robustum in Colorado
Click image to enlarge.

Colorado endemic: No
Global range: Colorado: local, in canyon bottoms of Spanish Peaks, Cuchara Valley, and La Garita Hills, west side of San Luis Valley. New Mexico: three northeastern counties bordering Colorado.
State range: Known from Huerfano, Las Animas, and Saguache counties in Colorado. Estimated range in Colorado is 1981 square kilometers (765 square miles), calculated in GIS by drawing a minimum convex polygon around the known occurrences (calculated by the Colorado Natural Heritage Program in 2008). Also known from New Mexico.

[+] Threats and Management Issues

Delphinium robustum is vulnerable because of its endemic distribution, small number of documented occurrences, possible population declines, and potential human-related and environmental threats. Threats to the long-term persistence of Delphinium robustum are mostly unknown because of a lack of species knowledge and research. Possible human-related threats to D. robustum include motorized and non-motorized recreation, structure construction, road construction and maintenance, erosion and sedimentation related to roads, livestock trampling, and changes to natural disturbance regimes (e.g., fire suppression). The extent of these activities near existing occurrences of D. robustum or in suitable D. robustum habitat is unknown. Disturbances and land management activities, such as burning, thinning, or grazing, may maintain suitable habitat for this species or negatively impact existing occurrences, depending on the disturbance intensity, frequency, and type. Possible environmental and biological threats to occurrences of D. robustum include environmental fluctuations (e.g., drought), non-native species invasion, extensive herbivory, succession, genetic isolation, hybridization, inadequate pollination, and global climate changes (Beatty et al. 2004).

[+] References

    • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.
    • Beatty, B.L., W.F. Jennings, and R.C. Rawlinson (2004, July 26). Delphinium robustum Rydb. (Wahatoya Creek larkspur): a technical conservation assessment. [Online]. USDA Forest Service, Rocky Mountain Region. Available: [Nov. 11, 2015].
    • Colorado Natural Heritage Program. 2006. The Third Annual Colorado Rare Plant Symposium: G2 Plants of Southeast Colorado. Symposium Minutes. Available on-line
    • Colorado Natural Heritage Program. 2012. Biodiversity Tracking and Conservation System. Colorado State University, Fort Collins, CO.
    • Colorado Natural Heritage Program. 2012. The Ninth Annual Colorado Rare Plant Symposium: G2 and G3 Plants of Southeastern Colorado. Symposium Minutes. Available on-line
    • Flora of North America Editorial Committee, ed. (FNA). 1993+. Flora of North America North of Mexico. Oxford Univ. Press, New York, Oxford.
    • Flora of North America Editorial Committee. 1997. Flora of North America north of Mexico. Vol. 3. Magnoliophyta: Magnoliidae and Hamamelidae. Oxford Univ. Press, New York. xxiii + 590 pp.
    • Gierisch, R. 1943. Specimen collections.
    • Harrington, H. 1959. Specimen collections at Colorado State University Herbarium.
    • Harrington, H.D. 1954. Manual of the plants of Colorado. Sage Press, Chicago. 666 pp.
    • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
    • Kartesz, J.T. 1996. Species distribution data at state and province level for vascular plant taxa of the United States, Canada, and Greenland (accepted records), from unpublished data files at the North Carolina Botanical Garden, December, 1996.
    • Lavender, A.E., M.M. Fink, S.E. Linn, D.M. Theobald. 2011. Colorado Ownership, Management, and Protection v9 Database. Colorado Natural Heritage Program and Geospatial Centroid, Colorado State University, Fort Collins, CO. (30 September).
    • Martin, W.C., and C.R. Hutchins. 1980-1981. A flora of New Mexico. 1980, Vol. 1; 1981, Vol. 2. J. Cramer, in der A.R. Gantner Verlag, K.G., Vaduz, Liechtenstein. 2591 pp.
    • Neely, B., S. Panjabi, E. Lane, P. Lewis, C. Dawson, A. Kratz, B. Kurzel, T. Hogan, J. Handwerk, S. Krishnan, J. Neale, and N. Ripley. 2009. Colorado Rare Plant Conservation Strategy, Developed by the Colorado Rare Plant conservation Initiative. The Nature Conservancy, Boulder, Colorado, 117 pp.
    • New Mexico Rare Plant Technical Council. 1999. New Mexico Rare Plants. Albuquerque, NM: New Mexico Rare Plants Home Page. (Latest update: 30 March 2012).
    • Painter, B., et al. 1978. Specimen collections at Colorado State University Herbarium.
    • Sivinski, R. 2011. Delphinium robustum, New Mexico Rare Plants. accessed online on 11/11/15 at
    • USDA, NRCS. 2013. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.
    • Weber, W. A. and R. C. Wittmann. 2012. Colorado Flora, Eastern Slope, A Field Guide to the Vascular Plants, Fourth Edition. Boulder, Colorado. 555 pp.
    • Weber, W.A., and R.C. Wittmann. 1996a. Colorado flora: Eastern slope. Revised edition. Univ. Press of Colorado, Niwot, Colorado. 524 pp.
    • Weber, W.A., and R.C. Wittmann. 2012b. Colorado Flora, Western Slope, a field guide to the vascular plants, fourth edition. Boulder, Colorado. 532 pp.

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