This species rather narrow oblanceolate leaves, short peduncle bearing several flowers, rather large though selnder bright pink corollas, and unusual stipules for Hippotis: these are narrowly triangular, acute to acuminate, and sparsely pubescence to often glabrous abaxially. Hippotis tubiflora has markedly sylleptic growth and is apparently rheophytic. The calyx limbs vary rather notably in size, from 9-18 mm long. They have five small acute or aristate teeth, and are closed in bud then open irregularly with usually one long slit and variously 2-5 lobes of inconsistent length. The calyx limb is also apparently sometimes deciduous in the upper part as the fruits develop. Several of the duplicates of the type of this name in fact have both flowerings stems and fruis that only have the bottom portion of the calyx limb remaining. Andersson reviewed this species and annotated the type specimen at K as being a mixed collection, but this appears to be only the variation between flowering and fruiting calyces. Also the stipules initially are strigose and that pubescence is often tardily deciduous, so there appears to be variation in this feature.

The corollas are mostly seen in bud. They are tubular along their length then flared in the lobe section, and have short lobes in bud that expand markedly in size later but are often not seen in their mature form. Steyermark separated Hippotis wurdackii from Hippotis tubiflora based in part on its apparently larger corollas, but these are similar in size to fully developed corollas of Hippotis tubiflora and these names were treated by Andersson & Rova (2004) as synonymous. Steyermark did not key or present a full description in that work for Hippotis tubiflora, so a full comparison between these species was not made there.

Hippotis tubiflora is quite similar to Sommera sabiceoides, which is sympatric but has calyx limbs that are deeply regularly 5-lobed and shorter white corollas. Andersson & Rova (2004) considered Hippotis tubiflora to be very similar to and perhaps not distinct from Hippotis subelongata, which has simliar acute glabrescent stipules; however Hippotis subelongata has well developed peduncles that are longer than the flowers and petioles along with longer calyx limbs, 25-28 mm long (vs. 9-18 mm long in Hippotis tubiflora). Hippotis tubiflora is also similar to Hippotis triflora, which also has well developed peduncles along with generally broader leaves.