Helenium microcephalum

{{Short description|Species of flowering plant}}

{{For|Helenium microcephalum Kuntze|Pentanema britannica}}

{{Speciesbox

| image = Helenium microcephalum, Dry Creek Lake, Briscoe County, TX, USA imported from iNaturalist photo 149483505.jpg

| genus = Helenium

| species = microcephalum

| authority = DC. 1836

| synonyms_ref = [http://www.theplantlist.org/tpl1.1/record/gcc-9165 The Plant List, Helenium microcephalum DC. ][http://www.iapt-taxon.org/nomen/main.php?page=art60 International Code of Nomenclature for algae, fungi, and plants (Melbourne Code)] see section 60.6

| synonyms = *Helenium oöclinium A.Gray, syn of var. ooclinium

• Helenium ooclinium A.Gray, syn of var. ooclinium
• Heleniastrum ooclinium (A.Gray) Kuntze, syn of var. ooclinium
• Heleniastrum oöclinium(A.Gray) Kuntze, syn of var. ooclinium

}}

Helenium microcephalum is a North American perennial plant in the family Asteraceae, commonly known as smallhead sneezeweed. It is found in the southwestern and south-central United States and northern Mexico.[http://bonap.net/MapGallery/County/Helenium%20microcephalum.png Biota of North America Program 2014 county distribution map]Turner, B. L. 2013. The comps of Mexico. A systematic account of the family Asteraceae (chapter 11: tribe Helenieae). Phytologia Memoirs 16: 1–100

Helenium microcephalum is an annual herb up to {{convert|120|cm|ft|abbr=on}} tall, with wings running down the sides of the stems. Leaves are narrow and elliptical. One plant can have 300 or more small spherical or egg-shaped flower heads, generally no more than 12 mm (half an inch) in diameter. Each head can have 400 or more minuscule disc flowers {{convert|1.2|–|2.4|mm|in|abbr=on}} across, each yellow or yellow-green toward the bottom but brown or red toward the tip. There are also 7-13 red or yellow ray flowers.[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250066855 Flora of North America, Helenium microcephalum de Candolle, 1836. Smallhead sneezeweed ]

;Varieties

• Helenium microcephalum var. microcephalum - Arizona, New Mexico, Oklahoma, Colorado, Texas, Coahuila, Nuevo León, Tamaulipas
• Helenium microcephalum var. ooclinium (A. Gray) Bierner - Texas, Coahuila, Chihuahua, Nuevo León, Durango, San Luis Potosí