Remijia densiflora is charcterized by its papery, glabrescent or appressed-pubescent, opposite, generally medium-sized (for Remijia) leaves with the higher order venation regularly and rather finely reticulated on the lower surface and the apices acuminate together with its inflorescences with well developed peduncles and several to numerous flowers grouped in subcapitate to congested-cymose heads. The calyx limb is deeply lobed, and the species as circumscribed by Steyermark (1972) shows notable variation in calyx lobe form and size. The calyx lobes vary from deltate to very narrowly triangular, from generally equal in size on an individual flower to markedly unequal, and from 0.5-5 mm long on the flowers and later elongating to up to 9 mm long on the fruits. This species is fairly commonly collected.

Steyermark (1972) recognized several subspecies and varieties of Remijia densiflora based mainly on the form and size of the calyx lobes. Their separation is outlined in the key here. There apparently is continuous variation in the characters that separate the subspecies, but two fairly well-marked groups can be separated; however re-evaluation of the status of these two subspecies may be useful now that more material is available of this species. Both subspecies are collected generally equally frequently. Steyermark recognized two varities of Remijia densiflora, with Remijia densiflora var. minima separated by its short deltate calyx lobes and markedly shorter corolla; this variety is poorly documented and it may deserve re-evaluation as to its relationship with the other plants included in Remijia densiflora.

Remijia densiflora is somewhat similar to Remijia tenuiflora, with generally leaves that are obtuse to acute at the apex and several flowers in usually racemiform inflorescences. Remijia densiflora is also similar to Remijia delascioi, with relatively quite narrow leaves. In general aspect Remijia densiflora is also somewhat similar to species of Malanea, which differ in their leaves with the higher-order venation closely lineolate and the fruits fleshy with a single seed.