Dipterostemon

Dipterostemon is a monotypic genus previously included in Dichelostemma native to the Western United States (Oregon, California, Utah, Arizona, New Mexico) and northwest Mexico. It is considered by some to be a member of the Themidaceae family. The Angiosperm Phylogeny Group III placed this family into Asparagaceae as of 2009 but the Jepson eFlora continues in 2021 to list it in Themidaceae. Its only species is Dipterostemon capitatus. In this paper Robert Preston proposed removing this species to an earlier name. In 2021 this name is accepted by Plants of the World Online, the Jepson Manual, and iNaturalist. The Flora of North American and World Flora Online continue to recognize Dichelostemma capitatum. Dipterostemon differs from the other species in Dichelostemma by having 6 stamens instead of three. Three subspecies are recognized. Corms are edible and were eaten by native populations who harvested the larger corms and replanted the cormlets.


Dipterostemon capitatus (Benth.) Rydb., syn. Dichelostemma capitatum (Benth.) Alph.Wood, is known by the common name of Blue Dicks. Capitatus, capitata and capitatum are the masculine, feminine and neuter forms of the Latin word for "having or forming a head". Three subspecies are recognized in 2021. Changes in the name and additional subspecies plays havoc with photos previously on the wiki named Dichelostemma capitatum as keys often require information not readily apparent in a photo (like size of filaments, perianth, pedicels, color of bracts, sometimes corms, height, etc.) And it is often difficult to learn the provenance of plants in cultivation. So this is our best guess for which subspecies are illustrated by previous photos.

Photos 1-3 by Bob Rutemoeller show the flowers in the middle of a Lupine and then alone where the leaves are shown as well. Another view shows the tube. Photos 4-5 were taken by Mary Sue Ittner. The 5th photo shows it flowering in front of Watsonia coccinea. The last photo of a dissected flower shows 6 stamens.

Dipterostemon capitatus, syn. Dichelostemma capitatum, Bob RutemoellerDipterostemon capitatus, syn. Dichelostemma capitatum, Bob RutemoellerDipterostemon capitatus, syn. Dichelostemma capitatum tube, Bob RutemoellerDipterostemon capitatus, syn. Dichelostemma capitatum, Mary Sue IttnerDipterostemon capitatus, syn. Dichelostemma capitatum, Mary Sue IttnerDipterostemon capitatus, syn. Dichelostemma capitatum, M. Gastil-Buhl

Photos 1-2 by Nhu Nguyen shows the vigorous root system of the plants. The thickened part of the root in photo 2 will eventually be consumed by the developing corm. Photo 3 by M. Gastil-Buhl shows corms grown by Jim Duggan on a 1 cm grid.

Dipterostemon capitatus, syn. Dichelostemma capitatum, roots, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, roots, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, corms, M. Gastil-Buhl

Dipterostemon capitatus ssp. capitatus is highly variable and widespread in Oregon and throughout the California Floristic Province in California. In coastal California (also Oregon and northern Baja California), Dichelostemma capitatum ssp. capitatum is likely the correct ID. When it comes to California's Mojave Desert and Sierra Nevada there is an overlap between this subspecies and ssp. pauciflorus.

In April of 2015, Travis Owen came across a large colony of Dipterostemon capitatus at the side of the road in Rogue River, Oregon. Photos below were of the colony, on a steep bank with Ceanothus, Toxicoscordion, and Arbutus trees surrounding the patch.

Dipterostemon capitatus, syn. Dichelostemma capitatum, April 2015, Travis OwenDipterostemon capitatus, syn. Dichelostemma capitatum, April 2015, Travis OwenDipterostemon capitatus, syn. Dichelostemma capitatum, April 2015, Travis OwenDipterostemon capitatus, syn. Dichelostemma capitatum, April 2015, Travis Owen

In order to illustrate the natural variation by locality of these plants in California, they are listed by county, loosely north to south:

Humboldt County photos taken by Mary Sue Ittner near Horse Mountain.
Dipterostemon capitatus, syn. Dichelostemma capitatum, Humboldt County, Mary Sue IttnerDipterostemon capitatus, syn. Dichelostemma capitatum, Humboldt County, Mary Sue IttnerDipterostemon capitatus, syn. Dichelostemma capitatum, Humboldt County, Mary Sue Ittner
Tehama County photo taken by Mary Sue Ittner at the Vina Plains.
Dipterostemon capitatus, syn. Dichelostemma capitatum, Tehama County, Mary Sue Ittner
Butte County - photos below were taken by Nhu Nguyen and Mary Sue Ittner. Many of them, if not all, were taken at North Table Mountain Ecological Reserve.
Dipterostemon capitatus, syn. Dichelostemma capitatum, Butte Co., Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, Table Mountain, Mary Sue IttnerDipterostemon capitatus, syn. Dichelostemma capitatum, Table Mountain, Mary Sue IttnerDipterostemon capitatus, syn. Dichelostemma capitatum, Table Mountain, Mary Sue Ittner
Photos 1-4 shows a rare white form. Photo 2 shows the white form growing next to a purple form.
Dipterostemon capitatus, syn. Dichelostemma capitatum, white form, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, white form, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, white form, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, white form, Nhu Nguyen
Colusa County - the photos below taken by Mary Sue Ittner April 2019 on Bear Valley Road.
Dipterostemon capitatus, syn. Dichelostemma capitatum, Bear Valley Road, Mary Sue IttnerDipterostemon capitatus, syn. Dichelostemma capitatum, Bear Valley Road, Mary Sue Ittner
Lake County - the photo below was taken by Mary Sue Ittner of a dwarf form growing in a wet serpentine area with Mimulus guttatus. It could be subspecies lacuna-vernalis, but it is not known from this county and it is impossible to tell from the photo identifying details whether it could be that subspecies.
Dipterostemon capitatus, syn. Dichelostemma capitatum in serpentine, Lake County, Mary Sue Ittner
Sonoma County - the photos below were taken by Bob Rutemoeller and Mary Sue Ittner. Photo 1 shows a population growing on a rock overlooking Highway 1, safe from predators no doubt. Photo 2 shows the plants growing in a grassy area near another local road.
Dipterostemon capitatus, syn. Dichelostemma capitatum, Bob RutemoellerDipterostemon capitatus, syn. Dichelostemma capitatum, Mary Sue IttnerDipterostemon capitatus, syn. Dichelostemma capitatum, Bob RutemoellerDipterostemon capitatus, syn. Dichelostemma capitatum, Mary Sue Ittner
Napa County - the photos below were taken by Nhu Nguyen. The first was taken at the Stebbins Cold Canyon Reserve. The next two photos show it growing with Delphinium nudicaule.
Dipterostemon capitatus, syn. Dichelostemma capitatum, Stebbins Cold Canyon Reserve, Nhu NguyenDipterostemon capitatus with Delphinium nudicaule, Napa Co, CA, Nhu NguyenDipterostemon capitatus with Delphinium nudicaule, Napa Co, CA, Nhu Nguyen
Contra Costa County - the photos below was taken by Nhu Nguyen from Mount Diablo State Park. Photo 2 shows a classic purple and orange contrast between Dipterostemon capitatus and Eschscholzia californica.
Dipterostemon capitatus, syn. Dichelostemma capitatum, Mount Diablo State Park, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, Mount Diablo State Park, Nhu Nguyen
Mariposa County - the photos below were taken by Nhu Nguyen. Photos 1-3 were taken on a roadside rock outcrop of CA HW140. Photo 3 shows the bulbs growing with a beautiful Parvisedum species on the rock outcrop. Photos 4-5 was taken on the Hite Cove Trail. Here the bulbs are contrasted against the orange of Eschscholzia caespitosa.
Dipterostemon capitatus, syn. Dichelostemma capitatum, HW140, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, HW140, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, HW140, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, Hite Cove, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, Hite Cove, Nhu Nguyen
San Benito County - the photo below was taken by Mary Sue Ittner at Pinnacles National Park.
Dipterostemon capitatus, syn. Dichelostemma capitatum at Pinnacles National Monument, Mary Sue Ittner
San Luis Obispo County - the photo below was taken by Mary Sue Ittner.
Dipterostemon capitatus, syn. Dichelostemma capitatum, San Luis Obispo County, Mary Sue Ittner
Santa Barbara - Photos below were taken at FigueroaMountain. The first photo was taken April 2005 by Mary Sue Ittner of a plant growing with Allium crispum. The second photo taken by M.Gastil-Buhl is likely to be this species as well.
Dipterostemon capitatus, syn. Dichelostemma capitatum with Allium crispum, Mary Sue IttnerDipterostemon capitatus, syn. Dichelostemma sp., Figueroa Mountain, M. Gastil-Buhl
Kern County - Two subspecies are present in Kern County. The first 5 photos below were taken by Nhu Nguyen at a rock outcrop outside of the town of Onyx on the western edge of the Mojave Desert. In photo 2, the background tree is a Joshua Tree (Yucca brevifolia), a landmark plant of the Mojave Desert. Although this is the right kind of habitat for spp. pauciflorus and could be that subspecies, plants don't seem to have dark bracts or longer than usual pedicels that are diagnostic for that subspecies. However, other plants in the same area had long pedicels. Photo 6 was taken by Mary Sue Ittner.
Dipterostemon capitatus, syn. Dichelostemma capitatum, HW178, Mojave Desert, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, HW178, Mojave Desert, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, HW178, Mojave Desert, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, HW178, Mojave Desert, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum, HW178, Mojave Desert, Nhu NguyenDipterostemon capitatus, syn. Dichelostemma capitatum in Kern County, Mary Sue Ittner
Los Angeles County - the photo below was taken by Lee Poulsen in the Antelope Valley California Poppy Reserve on the western edge of the Mojave Desert outside of Lancaster, CA on April 2, 2005.
Dipterostemon capitatus, syn. Dichelostemma capitatum, Antelope Valley California Poppy Reserve, Lee Poulsen
San Diego County - the photo below was taken by Jim Duggan.
Dipterostemon capitatus, syn. Dichelostemma capitatum, San Diego County, Jim Duggan

Dipterostemon capitatus ssp. lacuna-vernalis (L.W. Lenz) R.E. Preston, vernal pool blue dicks, is endemic to the western base of the Sierra Nevada foothills and adjacent Great Valley, ranging from Butte County south to Merced County at elevations between 30 and 270 m. It is found in open upland grasslands adjacent to vernal pools or in grassy swales in oak woodland. It is distinguished from the other two subspecies by having a scape less than 20 cm and a perianth tube under 4 mm. The outer perianth lobes are wider than the inner set of lobes. Photos from iNaturalist taken by natomapaul and Naresh Sukumar in March near Orangevale, California and shared under a CC BY-NC license. Last photo taken by Vince Scheidt.

Dipterostemon capitatus ssp. lacuna-vernalis, natomapaul, iNaturalist, CC BY-NCDipterostemon capitatus ssp. lacuna-vernalis, natomapaul, iNaturalist, CC BY-NCDipterostemon capitatus ssp. lacuna-vernalis, natomapaul, iNaturalist, CC BY-NCDipterostemon capitatus ssp. lacuna-vernalis, Naresh Sukumar, iNaturalist, CC BY-NCDipterostemon capitatus ssp. lacuna-vernalis, Naresh Sukumar, iNaturalist, CC BY-NCDipterostemon capitatus ssp. lacuna-vernalis, Vince Scheidt

Dipterostemon capitatus ssp. pauciflorus (Torr.) R.E. Preston, syn. Dichelostemma capitatum ssp. pauciflorum (Torr.) Keator, occurs in desert habitats of the southwestern United States (Arizona, California, Nevada, New Mexico, Utah) and in Northern Mexico. Besides the difference in where it grows, it is distinguished from ssp. capitatus by white or streaked purple instead of dark blue or purple bracts at the tops of the stem and flowers that grow on much longer pedicels (6-34 mm vs. 2-12 mm). There are also only 2-5 flowers in the average umbel. In ssp. capitatum there are 2-16. The two photos below were taken by Nhu Nguyen at a rock outcrop outside of the town of Onyx on the western edge of the Mojave Desert. A few of the plants had interesting and long pedicels. Photos above also taken near that spot listed under Kern County did not have the long pedicels raising interesting questions about the subspecies designation. Subspecies were generally not recognized in the later years when this plant was considered Dichelostemma capitatum.

Dipterostemon capitatus ssp. pauciflorus, syn. Dichelostemma capitatum, HW178, Mojave Desert, Nhu NguyenDipterostemon capitatus ssp. pauciflorus, syn. Dichelostemma capitatum, HW178, Mojave Desert, Nhu Nguyen

Photo below from iNaturalist taken by Jackie Grant in Utah in April and shared under a CC BY-NC-SA license.

Dipterostemon capitatus ssp. pauciflorus, Jackie Grant, iNaturalist, CC BY-NC-SADipterostemon capitatus ssp. pauciflorus, Jackie Grant, iNaturalist, CC BY-NC-SADipterostemon capitatus ssp. pauciflorus, Jackie Grant, iNaturalist, CC BY-NC-SADipterostemon capitatus ssp. pauciflorus, Jackie Grant, iNaturalist, CC BY-NC-SA

Photo below from iNaturalist taken by wirich in Arizona in April and shared under a CC BY-NC license.

Dipterostemon capitatus ssp. pauciflorus, wirich, iNaturalist, CC BY-NCDipterostemon capitatus ssp. pauciflorus, wirich, iNaturalist, CC BY-NC

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