Annuals, 20-100 cm, herbaceous or suffrutescent. Leaf blades oblanceolate to oblong or oblong-lanceolate, mid-cauline (1-)4-15(-25) mm wide. Heads on short, sometimes bracteate peduncles, not surpassed by distal leaves. Involucres (4.5-)6-9 × 9-15(-20) mm. Phyllaries in 3-4 series, loose, strongly unequal, apices broadly spreading to squarrose, ca. 0.9-1 mm wide, herbaceous. Ray florets (13-)20-36; corollas 6-11(-14) mm. Disc florets: corolla tubes ± equaling limbs. 2n = 12.

Flowering (Jul-)Aug-Oct. Sand or sandy loam, prairies, stream sides and bottoms, alkaline flats, salt marsh edges, roadsides; 1000-1700 m; Colo., Kans., Nebr., N.Mex., Okla., Tex., Wyo.

Diggs, Lipscomb, O'Kennon, Mahler, and Shinners, 1999, FNA 2006, Shreve and Wiggins, 1964,

Duration: Annual

Nativity: Native

Lifeform: Forb/Herb

General: Herbaceous or suffrutescent annuals or weak biennials, stems erect, to 100 cm tall, branching above, herbage sparsely to densely glandular, resinous, plants arising from a taproot.

Leaves: Alternate, sessile, oblanceolate to oblong or oblong-lanceolate, 2-5 cm long, 4-15 mm wide, becoming reduced distally, margins with 7-10 prominent teeth on each side, these mucronate or with a short bristle.

Flowers: Heads radiate, rays yellow, 20-36, the corollas 6-11 mm, disk florets yellow, several to numerous, the corolla tubes roughly equaling the limbs, involucres 6-9 mm long and 9-15 mm wide, phyllaries in 3-4 series, these loose and strongly unequal, the tips acute to acuminate or tapering to a short bristle, herbaceous and densely glandular-pubescent, these often reflexing in maturity, the heads solitary or corymbosely arranged, the peduncles short, sometimes bracteate, not surpassed by the distal leaves.

Fruits: Achenes pubescent, to 2 mm long. Pappus of numerous, capillary, unequal, scabrous bristles.

Ecology: Found on sand or sandy loam, in prairies, stream sides and bottoms, alkaline flats, salt marsh edges, and roadsides, from 3,500-5,500 ft (1067-1676 m); flowering August-October.

Distribution: Colorado, Kansas, Nebraska, New Mexico, Oklahoma, Texas, Wyoming

Notes: This species is not formally recognized as occurring in Arizona, but does occur in Texas and New Mexico. Shreve and Wiggins used only for family descriptions-not in K & P, McDougall, Jepson, or Shreve and Wiggins-More information needed for achenes, used Shinners & Mahler's Illustrated Flora of North Central Texas (authors: Diggs, Lipscomb, O'Kennon, Mahler, Shinners) sourced online; for further information-see http://artemis.austincollege.edu

Ethnobotany: Unknown

Etymology: Rayjacksonia is of uncertain origins, while annua means annual.

Synonyms: Haplopappus annuus, Machaeranthera annua, Sideranthus annuus

Editor: LCrumbacher 2011