Annuals to perennials, 4-80 cm, herbage glabrous, prominently sessile- to stipitate-glandular; taprooted. Stems erect to decumbent-ascending, branched basally (leafy throughout). Leaves mostly cauline; alternate; sessile to subpetiolate; blades 1-nerved (pinnately veined), linear to oblanceolate, margins coarsely serrate (teeth bristle-tipped), rarely entire (apices acute to obtuse). Heads radiate, in paniculiform or subcorymbo-cymiform arrays. ( Peduncles sometimes cobwebby.) Involucres hemispheric, (7-16 ×) 9-30 mm. Phyllaries 20-40 in 4-5 series, appressed or tips spreading to reflexed, 1-nerved (flat or proximally convex), linear to lanceolate or ovate-lanceolate, equal to subequal, white-indurate, margins of inner scarious (apices erect, loosely spreading, or recurved, green-herbaceous, acute to acuminate), faces glabrous or glandular. Receptacles shallowly convex, pitted, epaleate. Ray florets 14-46, pistillate, fertile; corollas yellow. Disc florets 25-130, bisexual, fertile; corollas yellow, tubes shorter than abruptly ampliate throats, lobes 5, erect, triangular; style-branch appendages deltate. Cypselae dimorphic, faces strigoso-sericeous; ray broadly ellipsoid to obovoid, 3-angled (thick-walled), 0-4-ribbed; disc broadly ellipsoid to clavate, ± radially compressed (thinner-walled), 5-9-ribbed; pappi persistent, of 30-40 brownish, unequal, barbellate, attenuate bristles in 3-4 series (about as long as disc corollas), outer thinner, terete, inner thick-flattened. x = 6.

R. L. Hartman (1990) informally recognized the three species of Rayjacksonia as an undescribed genus most closely related to Grindelia, Isocoma, Xanthocephalum, and other genera of Machaerantherinae with x = 6. The taxonomy was formalized by M. A. Lane and Hartman (1996). The Rayjacksonia species are coherent in vestiture, spinulose leaf teeth, heads borne singly, and rays with prominent, yellow laminae.