Culture
Easily grown in moist, gritty-gravelly, well-drained soils in full sun to part shade. Plants prefer cool summer conditions and often perform poorly south of USDA Zone 7. Best flowering typically occurs in full sun, but some part afternoon shade is needed in hot summer climates to help prevent the onset of leaf bleaching. Tolerates slightly alkaline soil. Also tolerates occasional brief periods of dry soil.
Noteworthy Characteristics
Gentiana acaulis, commonly known as stemless gentian or trumpet gentian, is a much-loved, dwarf, mat-forming, blue-flowered, alpine perennial that typically grows to only 4” tall but slowly forms a spreading ground cover-like carpet to 6” wide or more. It is native to alpine grasslands, rocky meadows, screes and alpine/subalpine coniferous forest at altitudes up to 9700’ in a number of European mountain ranges including the Alps, Pyrenees, Apennines, Cevennes, Cantabrians, Carpathians and Sistema Iberico. Glossy, evergreen, elliptic to lanceolate leaves (to 1” long) grow in small basal rosettes which form a tufted carpet over time. Showy, deep gentian-blue flowers (each to 2 1/2” long) in the shape of upward-facing trumpets bloom singly in May-June. Flowers appear to sit directly on top of the basal foliage (flowers are stemless as indicated by the specific epithet). Each flower has 5 sharp-pointed corolla lobes (petals) and a green-spotted throat. This gentian is noted for its deep true blue flower color. An image of this flower currently appears on the reverse side of the Austrian one euro cent coin.
Some gardeners consider Gentiana acaulis to also be a group name which includes a number of different species of very short-stemmed gentians all of which feature flowers that appear to sit directly on top of the leaf clump. Acaulis Group plants include G. alpina, G. angustifolia, G. clusii, and G. dinarica. Acaulis Group plants primarily differ from G. acaulis in leaf shape, flower shape, and markings within the flower tube.
Genus name honors King Gentius of Illyria (reign c. 180-168) B.C., who was reputed to have discovered the medicinal virtues of the root of the yellow gentian or bitterwort (G. lutea) from which a tonic bitters is still made.
Specific epithet means stemless or with very short stems.
Problems
No serious insect or disease problems. Gentian can be a difficult plant to grow well in gardens in the St. Louis area in large part because of the hot and humid summer conditions.
Uses
Excellent rock garden plant. Alpine gardens. Border fronts. Sunny foundation areas.