Phyllanthus warnockii, the sand reverchonia, is a plant species of the leaf-flower family. It is an annual that specializes in growing on sand dunes in the Southwestern United States and adjacent northeastern Mexico. It is poisonous to mammals.[3] Members of the Hopi Tribe in northeastern Arizona traditionally use the berries to oil and season cooking slabs for making corn wafer bread.
Sand reverchonia is a herbaceous annual species growing to a height of 10 to 50centimeters, though usually not taller than 30cm.[4] It grows from from a taproot with little branching.[5] It is monoecious, having separate flowers producing pollen or seeds, but having both types on the same plant.[6] Plants grow straight upwards, but often have numerous side branches that extend out widely and are hairless.[7] The lowest branches can be as much as 20–30cm long and 1.5–2millimeters thick.[5] Its sap is not milky.[4]
The leaves of sand reverchonia are attached by short leaf stems and are not lobed or toothed along their edges.[8] They attached alternately to the stems and are linear-oblong, shaped like a rectangle with rounded corners, but very narrow, to narrowly elliptic, having a shape where the leaf sides are gently curving from base to point with the widest part in the middle.[9] However, the seed leaves are attached oppositely and are enlarged to point that they look like narrow adult leaves.[7] Adult leaves are 1.5 to 4.5 cmlong and just 1.8 to 9mm across. The base of the leaves are two small reddish, papery stipules, 0.7–2.3mm.[5]
The flowers at the end of a branch
The flowers are in small clusters at the base of leaves on the side branches. Each cluster has a central flower with a pistil that will produce a fruit if fertilized and four to six pollen producing staminate flowers around it. The flowers are dark red-purple with four sepals on the pollen flowers and six, or less frequently five, on the seed flowers.[8] Each pollen flower is 1.5–2.5mm long and 0.7–1.5mm across while the 1.3–2.9mm long and 1.1–1.8mm wide in the seed flowers.[5]
The description by Asa Gray placed the species by itself in the genus Reverchonia, named for Julien Reverchon, a French emigrant to Texas who became plant collector and botanist. He collected the type specimen from a sandy island in the Brazos River near Seymour, Texas in 1879.[7]
Names
The new species name, warnockii, was selected by Webster to honor the contributions of Barton Holland Warnock to the botany of the Big Bend Reigion of Texas.[16] The previous species name, arenaria, was Botanical Latin meaning "sand" or "sandy place".[4] The common names of the species are also related to it being limited to sandy habitats,[4] for example sand reverchonia,[14]dune reverchon,[17]sand spurge,[4] and sandspurge.[9] Although, the species Euphorbia psammogeton is also known as sand spurge.[18]
In the Hopi language it is called pa:’tangwuva’pi because the fruits resemble small pumpkins, pa’tnga.[19]
Range and habitat
Sand reverchonia is native to seven central and western US states and to the state of Chihuahua in northeastern Mexico.[6] It grows in western Kansas, Oklahoma, and Texas.[4] It is rare in Colorado, only being recorded in Bent County.[20] Plants are found in the three southernmost Utah counties, Washington, Kane, and San Juan, and also in three northern Arizonan counties, Coconino, Navajo, and Apache. In New Mexico it grows in five widely scattered southern counties.[14] The Samalayuca Dune Fields that support the species in Chihuahua are south of Ciudad Juárez in the northeastern corner of the state.[21] Its elevation range is from 300to 1,800 meters (980–5,910ft) and its habitat is limited to areas of quartz sands such as dunes.[6]
Uses
The traditional way of preparing piki, a waffer bread made of corn, is on a stone cooking surface. Most frequently the seeds of watermelons or squash are used to oil the stone, but the fruits of sand reverchonia are also used at times.[22] In 1905 H. R. Voth recorded that the Hopi living at Oraibi, Arizona would use sand reverchonia as a medicine called táingwa similarly to the roots of the "blood medicine" Eriogonum annuum to prevent postpartum hemorrhage, though Voth did not record a method of preperation.[23][24]
Ackerfield, Jennifer (2022). Flora of Colorado (Seconded.). Fort Worth, Texas: Botanical Research Institute of Texas Press. ISBN978-1-889878-89-8. OCLC1350496037.
Welsh, Stanley L.; Atwood, N. Duane; Goodrich, Sherel; Higgins, Larry C. (1987). A Utah Flora. Great Basin Naturalist Memoirs, No. 9 (Firsted.). Provo, Utah: Brigham Young University. JSTOR23377658. OCLC9986953694. Retrieved 11 January 2026.
Booth, Nicola; Hamilton, Mark (2020). "Sand Spurge: The reintroduction". Australasian Plant Conservation. 29 (1). Australian Network for Plant Conservation: 25–27. Retrieved 10 January 2026.
CBR (9 March 2020). "Reverchonia arenaria". Lady Bird Johnson Wildflower Center Plant Database. Austin, Texas: University of Texas at Austin. Retrieved 10 January 2026.
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