Annuals, 7-15 cm (taprooted). Stems strigose. Leaves usually opposite proximally, sometimes alternate (distal); blades lance-linear to linear, 10-160 × 1.5-8(-12) mm, margins ciliate to 1/4 their lengths, hairs mostly less than 0.5 mm, faces strigose to strigillose (hair bases narrowly tuberculate), abaxial often gland-dotted. Heads 6-25+. Peduncles 0.2-0.5(-2) cm, lengths 1/20-1/2 times leafy portions of stems. Involucres 6-14 mm diam. Phyllaries 3-6 mm. Paleae oblong, 4-4.5 mm, acute to cuspidate. Ray florets 12-14; laminae ± elliptic, 5-17 mm (glabrous or puberulent). Disc florets 50+; corollas 2.5-4 mm. Cypselae black or mottled, 1.8-2 mm.
FNA 2006, Wiggins 1964, Kearney and Peebles 1969
Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Native annual herb; stems slender, simple or often branched above, 15-70 cm tall; sparsely to moderately pubescent with mostly appressed hairs, or almost. Leaves: Opposite below, usually alternate above; linear to lanceolate, 1.5-11 cm long, 1.5-14 mm wide, with a deep midvein; sparsely to moderately pubescent with mostly appressed hairs, or almost glabrous. Flowers: Heads solitary or in loose clusters; involucres 3-7 mm high; disk 6-14 mm wide, yellow; rays mostly 8-12, 8-17 mm long, yellow. Fruits: Cypselae 2.5-3 mm long, with no pappus. Ecology: Found on plains, arroyos, along washes, and on slopes; 2,500-8,000 ft (760-2440 m); flowers May-November. Distribution: NV, UT, AZ, NM, sw TX; south to c MEX. Notes: To get to this species look for the stiff, short hairs all over; mostly opposite, linear leaves with a defined, sunk-in midvein and dots of glands on the undersides; the showy yellow rays and disks, and the small, less than 2.5 mm long, black fruits (seeds). It becomes abundant in many areas after summer rains and covers fields in a blankets of gold, sometimes for miles, and can be identified to species from miles away by this.Two varieties thought to occur in the region: var. longifolia and var. annua; var. longifolia has wider leaves and slightly bigger flowers than var. longifolia (description as written accounts for both varieties). Ethnobotany: Ramah Navajo use as life medicine and fodder for sheep food. Etymology: Heliomeris is from ancient roots helio- for sun loving and meros- meaning part, while longifolia means long leaved. Synonyms: Gymnolomia longifolia, Viguiera longifolia Editor: SBuckley 2010, FSCoburn 2014