At the 24 hour Eslite on Dunhua I have seen a series of books on useful plants in Taiwan. I recal one for sure on edible plants and I vaguely recal one used for industrial purposes which I assume would include dyes.
Beyond that I would head to the handicraft centre near CKS memorial and look for the hand dyed stuff there. There are a few village coops that have restarted traditional dying and would be the logical places to contact about this.
Apparently Sanxia has an indigo dyeing handicrafts cottage industry.
This morning I went for a walk, and I came across a few more unidentified wildflowers. I saw lots of these yellow flowers:
I also saw some different yellow flowers which were much smaller and only had five petals, and they were part of a plant which looked similar to clovers, except that each of the three leaves was partially split in two:
Also, I saw a bunch of very tiny bluish-purple flowers:
(I know that the flowers in that picture are a little blurry, but the diameter of each flower was only about 3 or 4 mm, so it was very hard to get a clear picture.)
Also, I saw some Lantana that were different colors than the ones that I saw last week. (The ones I saw last week are on Page 1 of this thread.) The Lantana that I saw last week were red, orange, and yellow, but today I saw some Lantana that was pink ones mixed with yellow ones. Look at this:
And this Lantana has flowers which are light purple, but yellow in the center, which looks kind of strange:
Also, today I took a close up of a Bidens pilosa, which is the most common wildflower in Taiwan. This picture looks much better than the picture that I posted on Page 2 of this thread:
Does anyone know the English name for Bidens pilosa? (It is not a daisy.)
Dude! Google!
This looks like Oxalis or wood sorrel.
Spanish Needle ( in the US [south] and the Caribbean).
Chris, thanks a lot! I’m sure that you are right that it is Wood Sorrel (Oxalis) because I Googled it after you told me about it. However, I can’t tell whether it’s Oxalis stricta or Oxalis dillenii. Do you know which one it is?
About the other yellow flower: I think it might be “Cats Ear” (Hypochaeris radicata), but that’s just a guess based on comparing it with lots of pictures of flowers that I have found on the internet. Please correct me if I’m wrong.
Wookiee, thanks for telling me that the white flowers which are ubiquitous in Taiwan are called “Spanish Needles”.
By the way, does anyone know the Chinese names for any of these flowers?
Dude! Like, DUDE! 
Sandman,
I know that you already told me about Spanish Needles, but how about all of the other flowers?
By the way, the Wikipedia article that you quoted didn’t mention the tones of “xian feng cao”, so I looked up the characters. I found out that the correct pronunciation is xiánfēng cǎo.
Mark
I discovered that 咸豐草 (xian2 feng1 cao3) is not the right name for the white and yellow flowers. The correct name is 鬼針草 (gui3 zhen1 cao3), which means “Ghost Needles”.
Also, I found out that the yellow flowers which I posted on December 29 in this thread (on Page 5) are not “cats ears” because the leaves are completely different. The leaves of these yellow flowers look like grass. So this flower is still unidentified. (I can take a picture of the leaves of this flower if it would help to identify it.)
Also, today I took a picture of some unidentified purple flowers. They were growing on a wild bush which had long branches and thorns. Here’s what it looked like from a distance:
And here’s a close-up:
And I also saw some very tall yellow flowers. They were more than one meter tall. I couldn’t get a close-up of them because the weeds were too thick. Here’s a picture of the flowers:
And here’s a picture of the leaves for these flowers:
Does anyone know the names of these flowers?
Interesting. Any links?
I have some indigo – I’ll play a bit with it soon. I’m hoping to find some plants that do nice, fast yellows or reds. The only reasonably priced companies in N. America selling plant dyestuffs won’t ship here.
That would be bougainvillea, an escaped ornamental. Not native. Colours range from white through pink and an umber to dark fuschia, forms range from a compact branched and bushy form to a very thorny long-stemmed creeper.
Thanks a lot, urodacus! Now that leaves only two more unidentified wildflowers. I’m going to go out now and take pictures of the leaves of the short yellow flowers, and also I’ll see if I can get a closer picture of the tall yellow flowers. I’ll post the pictures here when I get back.
Popular ornamental throughout the world, in places where it doesn’t dip below freezing.
I just got back. I tried to take a picture of the leaves of the short yellow flowers, but there were so many green weeds and grass under the flowers that in the pictures, it would be hard to tell which leaves belong to the flowers and which leaves belong to other weeds. So I tore off a leaf and when I got home, I took a close-up picture of the leaf laying on a piece of blank paper.
Here’s the picture:
Earlier, I said that the leaves were like grass, but now I discovered that unlike grass, the leaves have “teeth”. (They are soft “teeth”, though. They aren’t thorns, like holly has.)
Also, I took a close-up of the very tall yellow flowers. These flowers (including the branches) were about 1½ meters tall! Here’s the picture:
And here’s what the tall yellow flowers look like from a distance:
These tall yellow flowers are still unidentified.
And the short yellow flowers that I posted on Page 5 of this thread (the first picture in my Dec. 29th 15:36 post), which has leaves like I posted above, is also still unidentified.
Tentative guess:
Farfugium japonicum var. formosanum
blog.roodo.com/abun3/archives/4463243.html
Not sure about the leaves, though…
Thanks, Chris! The flowers at that website look exactly the same as the tall yellow flowers that I took pictures of. The leaves look a lot different than the leaves in the picture that I posted at the bottom of Page 5 of this thread, but I might have accidentally taken a picture of the leaves of a different weed. I’ll go back tomorrow and check the leaves. (It’s getting too dark to go back today.)
Makes me think of Volkwagen for some reason…
Fahrvergnügen?
Here’s one I see a lot in the city, hanging from people’s rain gutters:
Creeping Inch Plant (Callisia repens), a kind of spiderwort.
Today I went back and looked at the tall yellow flowers to see what kind of leaves the plant has. I found out that the leaves are all exactly like in the picture that I posted at the bottom of Page 5 of this thread. So I don’t think these flowers are Farfugium japonicum var. formosanum because even though the flowers look identical, the leaves are completely different. So that was a case of mistaken identity.
So the tall yellow flowers as well as the short yellow flowers are still unidentified.
If anyone would like to see these flowers first-hand, you are welcome to come to northern Miaoli County, and I’ll show the wildflowers to you. (The flowers are all in a very undeveloped area which is south of the town of 竹南.)