Japanese Rush, Japanese Sweet Flag, Grassy-leaved Sweet Flag 'Licorice'

The US FDA has banned the sale of A. gramineus and A. calamus as medicine, as the root has proven to be carcinogenic even at low doses.

EDIT

first of al gramineus doesn't prove to be carcinogenic, it does contain beta asarone but not as much as acorus calamu...Read Mores. second it also depends if its a triploid or diploid , triploid species contain up to 11 % B-asarone while diploid contain around 0,2 % B-asarone. A-asarone is absent in most species but is present in gramineus. A-asarone is a anti-carcinogen.

so it's not the plant that's carcinogenic , it's the genetics and combination of constituents. Cultivars bred for consumption are often lower in B-asarone. B-asarone rich plants have a more wintergreen like taste somewhat like gaultheria procumbens but stronger and almost nutmeg like. while very sweet liquorice tasting plants like this cultivar has more A-asarone and less B-asarone.

Triploids ( from india etc) are often unsuitable for long term use , american diploid species are more suited for long term use. However like with any herb there is a rule of moderation.

very cold tolerant, survived 2 winters on my balcony in small containers. beautiful foliage that shine and almost reflect sunight, you should plant these in full sun they just look better that way. in light shade or partial sun they develop more brighter green foliage but they perform less.

it can tolerate very wet conditions but unlike acorus calamus or most gramineus cultivars this one can withstand drought better than others. Flowers are a bit like pilea or pepperomia flowers, they add some interest but they are very tasty, pick them when they are young and fresh.

the foliage also tastes nice , the tuber isn't that big compared to others and that was a bit of a letdown however the foliage taste almost as strong. Slow growing and slow spreading you should propagate these by divsion, they are very tolerant of dividing - they will have slow growth until they get established.

in my opinion this one is the best cultivar regarding winter interest, when the sun hangs low the gleaming foliage looks beautifull - i will make a picture next winter.