This species is characterized by its stipules with obtuse to rounded lobes, robust leaves, robust purple pyramidal inflorescences, pedicellate flowers, stout tubular purple corollas with dense hirsute pubescence on the outside, rounded somewhat large fruits, and pyrenes with sharply acute ridges. This species is frequently collected and showy. The calyx limb on the majority of plants ranges from ca. 0.5 mm long and subtruncate to 1.8 mm long and lobed for 2/3 or so. The inflorescence axes mostly vary from puberulous to pilosulous. The corollas are cylindrical to funnelform and externally densely pubescent with well developed, multicellular, stout, pink to purple trichomes.

This species is variable in several features, and several of its most distinctive forms have been named but are not completely separable morphologically, at least on dry material. The type of Palicourea lasiantha and other plants from the same region have puberulous inflorescence axes, a cylindrical puberulous hypanthium, subtruncate to lobed calyx limbs ca. 1 mm long, corollas that are tubular in bud and externally have trichomes of generally uniform length, 0.5--1 mm long. The type of Palicourea irrasiflora is similar to this, and probably from the same region. The type of Watsonamra sordidiflora is similar but has a shorter calyx limb, ca. 0.5 mm long. The types of Palicourea condensata and Palicourea lagesii are similar to that of Palicourea lasiantha, except they have pilosulous subglobose hypanthia.

Some plants from Ecuador and Colombia have densely hirtellous or lanose inflorescence axes and hypanthia, lobed calyx limbs 1--1.5 mm long, and corollas that are subglobose to obovoid in bud and externally densely shaggy-pubescent with trichomes 1--3 mm long. These plants are distinctive, and were described as a narrow endemic in Ecuador called Palicourea anianguana. More material now documents plants with these features from southern Colombia through southern Ecuador, at 240--1200 m. In Colombia, only this form is found in Putumayo and Caquetá while the "lasiantha" form is found in Amazonas. In Ecuador these plants are generally found at relatively low elevations in the northern provinces, while the "lasiantha" form is found in the southern provinces and more common at relatively higher elevations. However, these two forms are not completely allopatric; some plants are intermediate in trichome length and form; and the pubescence of the inflorescence axes and hypanthia on plants with shaggy-pubescent corollas varies from densely lanose or hirtellous to sparsely pilosulous. Thus, Palicourea anianguana appears to be a well-marked form that is not completely distinct from the "lasiantha" form; further study with field observations and other types of data will help clarify this.

Some other plants with well developed (to "shaggy") pubescence on the outside of the corolla and well developed calyx limbs, 1.8--2.5 have been separated as Palicourea pachycalyx. These have hypanthia that vary from cylindrical to subglobose, and are found in scattered localities in southern Colombia, eastern Peru, western Brazil, and eastern Bolivia. The variation in calyx length is now documented as continuous, and these can no longer be separated so this name is synonymized here.

Palicourea lasiantha is similar Palicourea lachnantha, Palicourea guianensis, and Palicourea mansoana.