Gentiana thunbergii

Family: Gentianaceae

What it is like

Gentiana thunbergii is a ANNUAL/BIENNIAL growing to 0.2 m (0ft 8in). It is in flower from July to September, and the seeds ripen from August to October. The species is hermaphrodite (has both male and female organs) and is pollinated by Bumblebees, butterflies. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.

Height (m): 0.2

Where it is found

Sunny places in lowland and mountains, C. and N. Japan.

E. Asia - China, Japan, Korea and Manchuria.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 1

Young plants and flower buds - cooked.

Medicine

Rating: 2

Although we have no record of medicinal use for this species, like most other members of this genus the root probably contains various bitter compounds and can be used as a general tonic for the digestive system. See G. lutea for more details of potential uses.

Other

Rating:

How it is grown

In general, gentians require a moist well-drained soil in a sheltered position, a certain minimum of atmospheric humidity, high light intensity but a site where temperatures are not too high. They are therefore more difficult to grow in areas with hot summers and in such a region they appreciate some protection from the strongest sunlight. Most species will grow well in the rock garden. A moisture loving plant, preferring to grow with full exposure to the sun but with plenty of underground moisture in the summer, it grows better in the north and west of Britain. Plants are intolerant of root disturbance.

Propagating it: Seed - best sown as soon as it is ripe in a light position in a cold frame. It can also be sown in late winter or early spring but the seed germinates best if given a period of cold stratification and quickly loses viability when stored, with older seed germinating slowly and erratically. It is advantageous to keep the seed at about 10°c for a few days after sowing, to enable the seed to imbibe moisture. Following this with a period of at least 5 - 6 weeks with temperatures falling to between 0 and -5°c will usually produce reasonable germination. It is best to use clay pots, since plastic ones do not drain so freely and the moister conditions encourage the growth of moss, which will prevent germination of the seed. The seed should be surface-sown, or only covered with a very light dressing of compost. The seed requires dark for germination, so the pots should be covered with something like newspaper or be kept in the dark. Pot up the seedlings into individual pots as soon as they are large enough to handle and grow on in light shade in the greenhouse for at least their first winter. The seedlings grow on very slowly, taking 2 - 7 years to reach flowering size. When the plants are of sufficient size, place them out into their permanent positions in late spring or early summer. Division in March. Most members of this genus have either a single tap-root, or a compact root system united in a single root head, and are thus unsuitable for division. Cuttings of basal shoots in late spring.

Best place to grow: Cultivated Beds;

Habit: Annual/Biennial

Hardiness:

Growth:

Soil: Light (sandy), medium, heavy (clay)

Shade: Semi-shade, no shade

Moisture: Moist

Things to keep in mind

Its other names

Local names

Synonyms

G. japonica. Maxim. G. trinervis.