Japanese sedge
Carex kobomugi

Family: Cyperaceae

What it is like

Carex kobomugi is a PERENNIAL growing to 0.2 m (0ft 8in). See above for USDA hardiness. It is hardy to UK zone 6. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and is pollinated by Wind. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist or wet soil. The plant can tolerate maritime exposure.

Height (m): 0.2

Where it is found

Sand dunes along the seacoast all over Japan.

E. Asia - Japan, Korea, Manchuria.

Conservation Status: This taxon has not yet been assessed.

Countries/locations it is found in

Asia, China, Japan, Korea, Manchuria, North America, Russia, Taiwan, USA.

How it is used

Food

Rating: 1

Root - cooked. Seed. An emergency food, used when all else fails. The seed is very small and would be fiddly to use.

Root: includes bulbs, corms, tubers, rhizomes etc.

Seed: includes nuts, cereals, peas and beans.

Medicine

Rating: 0

Other

Rating: 2

Environmental Uses: Land reclamation; Landscape improvement; Soil conservation. Possible benefits in using C. kobomugi for dune stabilization in its native range, but there are considerable doubts raised about its relative effectiveness compared to native species outside of this range.

How it is grown

We have very little information on this species and do not know if it will be hardy in Britain, though judging by its native range it should succeed outdoors in most parts of this country. It is likely to tolerate maritime exposure. The following notes are based on the general needs of the genus. Easily grown in a damp to wet soil in full sun or shade. Members of this genus are rarely if ever troubled by browsing deer.

Propagating it: Seed - sow in situ in the spring in a moist soil in light shade. If seed is in short supply it can be sown in a cold frame and be planted out in the summer. The seed usually germinates in 2 - 6 weeks at 15°c. Division in spring. Very easy, larger clumps can be replanted direct into their permanent positions, though it is best to pot up smaller clumps and grow them on in a cold frame until they are rooting well. Plant them out in the summer or following spring.

Best place to grow: Bog Garden; Cultivated Beds;

Habit: Perennial

Hardiness: 6-8

Growth:

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

Shade: Semi-shade, no shade

Moisture: Moist, wet

Things to keep in mind

A harmful, exponentially spreading, robust, mat-forming, and dominant perennial invader. An introduced species to the US to stabilize dunes its distribution in the United States now extends from Rhode Island to North Carolina. In Connecticut - Potentially invasive, banned. In Massachusetts - Prohibited

Its other names

Local names

Japanese sedge; sea isle Japanese sedge; Asiatic sand sedge. Chinese: shai cao.

Synonyms

C. macrocephala. non Willd.