Herbaceous perennial with a basal rosette of leaves and a scapose stem to 1.5 m tall; basal leaves linear, up to 1 m long, entire or rarely with one or two spinose teeth; cauline leaves few and reduced; inflorescence a compound umbel with compact head-like umbels terminating the branches; heads ovoid or ovoid-oblong, 12-25 mm long, 10-15 mm wide, with several ovate or lanceolate basal bracts and similar, but smaller bractlets within the head that barely exceed to the length of the fruits; corolla cream colored or bluish purple; fruit ovoid, 3-4 mm long with scales at the angles and smaller scales between. Flowering June through September.
There are no other Eryngium species with linear leaves in New Mexico. The entirely Mexican Eryngium longifolium Cav. is distinguished by spinose-ciliate, bristly or spinulose-dentate leaves and subglobose to ovoid heads about as long as broad. It also usually occurs in drier habitats at higher elevations.
New Mexico: Hidalgo County at Las Playas Springs; Arizona, Pima County north and east of Tucson and Cochise County in upper San Pedro valley; Mexico, Chihuahua northwest of Casas Grandes; Sonora east of Esqueda; Sierra Madre of Durango, Jalisco, Nayarit and Zacatecas.
1,310 m (4,250 ft) in New Mexico. Wet soils of aridland spring ciénegas in desert scrub or oak woodland.
Aridland spring habitats are being reduced in number and size throughout the range of E. sparganophyllum (Stevens and Meretsky 2008). Las Playas Springs have been dried by the Playas copper smelter and this species is probably extirpated from New Mexico. The few remnant ciénegas in the Animas Basin of Hidalgo County, New Mexico have been searched without discovering additional populations of this plant (Sivinski and Tonne 2011). It is still extant at a few vulnerable ciénegas in Arizona and rarely collected in western Mexico. This wetland species is rare and endangered in the United States, but additional information is needed on its distribution and abundance in Mexico.
Sivinski, R.C. and P. Tonne. 2011. Survey and assessment of aridland spring ciénegas in the southwest region. Section 6, Segment 25, Progress Report submitted to: NM Forestry Division, Santa Fe and USDI-Fish and Wildlife Service, Region 2, Albuquerque, New Mexico. Available http://www.emnrd.state.nm.us/SFD/ForestMgt/documents/SWCienegaSurvey.pdf
Gray, A. 1853. Plantae Wrightiana, Part 2, Smithsonian Institution, Washington DC. pg. 65.
Arizona Game and Fish Department. 2004. Arizona eryngo. Unpublished abstract compiled and edited by the Heritage Data Management System, Arizona Game and Fish Department, Phoenix, Arizona. Available http://www.azgfd.gov/w_c/edits/documents/erynspar.d.pdf
Mathias, M. E. & L. Constance. 1941. A synopsis of the North American species of Eryngium. American Midland Naturalist 25(2): 361-387.
Stevens, L.E. and V.J. Meretsky (eds.) 2008. Aridland springs in North America: ecology and conservation. The University of Arizona Press and The Arizona-Sonora Desert Museum, Tucson.