It was moved from its original genus Chelone to Penstemon in 1825, and was designated the type species of the new section Fasciculus in 1962.

[2] The plant's flower cluster (inflorescence) is a thyrse, which has a long main axis and many shorter sub-axes.

Using ethyl acetate extracts from the leaves, researchers were able to identify a new iridoid chemical they named pensteminoside.

[8] Other compounds found in the leaves include plantarenaloside, globularisicin, luteolin, diosmetin, verbascoside, and martynoside.

[7] The genus name Penstemon was given by American geographer and botanist John Mitchell based on its characteristic large sterile stamen.

[2][1][13] Botanist Richard Myron Straw established sections and subsections for the genus Penstemon in 1962.

[14] In Kunth's original publication on the species, the habitat was described as cold places on the slope of the volcano Nevado de Toluca in central Mexico.

[4] Poiret designated a location near Tolú in Colombia as the type locality of Penstemon gentianoides.

[15] Penstemon gentianoides is found in the herbaceous layer of Mexican mountain pine (Pinus hartwegii) forests alongside Senecio platanifolius and Muhlenbergia macroura.

[16] While Penstemon gentianoides is self-compatible and can be pollinated from different flowers on the same plant, cross-pollination leads to the production of more seeds and fruits.

[7] A 2011 study demonstrated that certain monoterpene extracts from the roots of the plant did possess anti-inflammatory properties in a laboratory setting on a similar level to the common drug indomethacin.

[20] Other folk medicine applications for the plant include using it as an emollient, balsamic, laxative, and anti-rheumatic.