This species can be recognized by its rather robust habit; its small intrapetiolar stipules; its terminal cymose inflorescence; its showy, rather large, reddish orange, 6-lobed corollas with the tubes 32-45 mm long and densely bearded in the throat; and its drupaceous fruits with numerous seeds in each pyrene. Boom (1984) did not detail the habitat of Isertia spiciformis, which seems to be ecologically rather widespread. Boom (1984) did note that in his circumscription, this species is quite variable morphologically, in particular in leaf form and texture, degree of development of the inflorescences, and distribution and density of pubescence, with continuous variation among all the forms. He did suggest that some of the variation may be correlated with geography and the situation might deserve re-evaluation with more specimens and field observations.