It has linear grassy-like leaves, long thin stem and fragrant yellow or lemon-yellow flowers.

[3][4] The base of the plant is covered by fibres from the remains of the previous season's leaves.

[6][10][11] It has a slender, hollow, flowering stem that grows up to between 15–45 cm (6–17.5 in) long and 2–3 mm wide.

[6][9] The unbranched stems have between 1 and 2 flowers at the terminal ends, in early summer, between May and June.

[5] The drooping (obovate shaped) falls have a wide blade (about 1 inch wide and 4 inches long), which have purple-brown or red-brown stripes, lines or spots over a deeper yellow centre or signal patch.

[19][18][23] The Latin specific epithet forresti refers to the 19th century plant collector and explorer George Forrest.

[24] It was first published and described by William Rickatson Dykes in Gardeners' Chronicle (of London), on page 418 in 1910.

[19] This plant has gained the Royal Horticultural Society's Award of Garden Merit since 1994,[15][20] as well as being an accepted name.

[3][8] It grows on the alpine meadows and mountain pastures at altitudes of 2,900–4,300 m (9,500–14,100 ft) above sea level.

[29] They like wet soils, but only during the growing season, if the rhizome and roots are exposed to constant moisture, it is likely to suffer from fungal infections.

[16][21] Unlike, other Sino-Siberians, Iris forrestii prefers positions in partial shade but can tolerate full sun.

[8] Also propagation is easier carried out by division of the rhizomes, rather than growing from seed which takes at least 3 years to get the plant to flowering maturity.

[16] A specimen exists in Royal Botanic Garden Edinburgh, which was collected by Forrest on 15 June 1906.

[4] Known Iris forrestii cultivars include 'Gelber Knirps', 'King's Forrest', 'Tetrafor', 'Yellow Apricot',[18] and 'Charm of Finches'.

[18] They are generally smaller than typical Siberian iris, but taller than Pacific Coast irises.