This plant was sold to me as Alpinia formosana and I have no reason to doubt that. The usual common name is "pinstripe ginger" because it has very smart thin pale stripes on the leaves. It is a member of the same plant family as ginger, the Zingiberaceae. It is in the same genus as the galangal, another spicy root used in a lot of east Asian cooking. This species does not appear to be used in cooking, though it does have slightly smelly tubers that, like ginger and galangal, run parallel to the surface of the soil. The leaves smell very nice if crushed, a woody, resiny fragrance that is not quite like any others I have smelt.
The Chinese name is given as 美山姜 měi shān jiāng, meaning "beautiful mountain ginger". "Mountain ginger" is the name for many Alpinia species. The specific name "formosana" would appear to be from formosus meaning "finely-formed, beautiful, handsome" in Latin, so the Chinese name is simply a translation of the botanical name. At least, for one of the meanings. The plant was first described from Taiwan, which was called Formosa by the Portuguese because it was so beautiful. Its native range is from the south of Kyushu (the most southerly large island of Japan), through the Nansei-shoto (Ryuku Islands) to Taiwan.
I have found it very easy to grow on an east-facing windowsill. The central heating is set to 16ºC. If I forget to water it often enough it gets dried edges on the leaves and new leaves may not unfurl correctly. It drinks a lot of water because of the large leaves. It does not seem to be fussy about humidity. The plant will get quite large indoors, these are up to 1.5 metres and spread quickly when happy. They will fill a pot quite quickly.I have never had any pests on it that I noticed.
If the leaves do get damaged, it can be renewed quite easily by chopping it down to within a handbreadth of the soil and letting it grow again. I have only had them flower twice in 8 years. I assume this is a combination of letting them get sufficiently potbound while remembering to water them often enough. They seem to be happy with relatively little light, though perhaps they would flower more readily with more light.
They are easy to propagate by division. I just hack a potful into four pieces and plant them into four plant pots. Which is why I have no room left on my windowsill. I use a coir-based compost with some dolomite and rock phosphate added to counteract the potassium hoarding tendency of the surface of the coir fibres.
It likes to be fed. I use a very dilute fertiliser in every watering except in the depth of winter when I might occasionally water with just water.
If you open this photograph in a new tab and expand it, you can see a drop of nectar sitting at the very top of the red patch. It is very viscous and, though it was a tiny fraction of a drop, was enough to get a little taste of sweetness. As there are few poisonous gingers, I tried eating one flower. Cardamoms give me migraines but luckily that did not happen with this one. It did have a quite hot gingery taste for a brief time. The flowers have no detectable smell, as far as I could tell.
This photo is of a slightly older flower, you can see that the pale white stigma has curled down, away from the thick, pale yellow stamen. The stamens were producing pollen even in the younger flower.
You can see the pollen in this image of the first flower I showed. The two little bits of fluffiness at the bottom of the stamen, one each on the cloven points, are the front of two long rows of pollen on the underside of the stamen. Directly under the little pink eyes.
In this view you can see the start of those two rows of pollen. You can also see a little bit of distortion at the top of the pointillist path of red and pink that shows where the nectar drop sits.
I have read that the plant is quite hardy outdoors but I presume it does not get as tall and flower as easily. According to a plant propagation company in the USA, if you tissue culture the plant it loses the stripes on the leaves. This would seem to indicate that the variegation is one of those types produced by a viral infection. Quite a well-behaved virus, it seems. My plants have varying amounts of stripiness, perhaps because some growing points outrun the virus for a while.
