Sudden infestation with this yellow flowered low-leaved tall gangly plant

[Kay Lancaster]

Try pulling one up... you may find they're attached to an underground root and stolon system, in which case you may be dealing with Canada thistle, Cirsium arvense, a noxious weed* in California, and you might want to consider some minor chemical warfare, as fragments of the underground portions of the plants about 3/8" long can start new ones, as can all the seeds.

They can basically take over an area in a few years.

Seeds last up to about 20 years in the soil, and can travel miles on the wind because they have a little "parachute" of hairs (pappus), and also many songbirds eat the seeds.

*Noxious weed is a legal definition, meaning the plant is a peril to agriculture. I think C. arvense is a class B, but it's been 30 years since I lived in CA, so you might want to check it. In some counties, everyone may be required to control it, in which case you're legally obligated to deal with it.

I control it here in my Oregon yard with heading the flowers** as soon as I see them, and spot applications of glyphosate on established plants in the fall. Heading has to be done vigilantly-- at least once a week.

**Canada thistle is a member of the Asteraceae (also known as the Compositae) the dandelion family -- each of those purple "petals" is an entire flower, and the flowers eventually develop one-seeded fruits that are dispersed by birds and wind.

FWIW, I had a bunch of downed trees a couple of years ago, and burning them was the only practical means I had to get rid of them. So I built the bonfire on top of a big Canada thistle to get an idea of what might happen in a wildfire. The fire burned for about 6 hours, got very hot, and left a lot of very alkaline ash. Next year, guess what I had under the bonfire site? Only the Canada thistle survived, and it was doing well.

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[Drew Lawson]

His plant's flowers looked too large for Canada thistle, at least based on the ones I deal with (in Ohio). But I suppose that might vary with growing conditions.

I made the mistake of ignoring them. They got well established in the area that I just returned to a vegetable garden this year. I tilled, which broke up the underground network (or most of it), but I still have to get the survivors before they have a chance to reestablish it.

But till & trowel isn't an attractive solution if they are in the lawn.

I never had much success with glyphosate. (I keep it on hand for poison ivy and a couple other special cases.) I attributed that to the root network.

One end of the yard is a garden with Canada thistle, the other end is lawn with Bermuda grass (the undesirable sort).

I have a way of attracting invasive weeds, I suppose.

[chaniarts]

thank you, but i already have my own set of these, along with brown recluse spiders, so need no more. what i also have a lot of and encourage are funnel spiders and tarantulas, but not indoors.

[Danny D.]

Thanks for that information.

Here's a picture of the underside of the wild mustard flower:

Is the green arrow pointing to a (football-shaped) sepal?

[Danny D.]

Hi Kay,

I started pulling one up, then another, and another, and another, until ... after a long while ... I filled my chest-high green recycling bin with the thistle!

I'm not sure how they process those things at the town recycling center - but those thistle thorns are nasty!

[Danny D.]

Worse. Purple *thorny* thistle weed!

And, I might add, the photos below should show why I've grown to instantly hate pulling out this purple thorny thistle weed!

1. I knew these dainty rubberized garden gloves didn't stand a chance:

1. And, I instantly realized these leather & cloth gloves wouldn't work:

2. I wasn't shocked when the thorns went right thru deerskin gloves:

1. But, I was surprised thick pigskin was no match for the thorns:

2. At the pressure you need to grasp & pull, even the thicker cowhide gloves were painfully allowing thorns to puncture me:

1. I was almost out of options, when I grabbed my heavy gas welding gloves - which hadn't been used in years, so they were as stiff - and even they allowed a few thorns in - but for the most part, they were the *only* gloves that weren't too painful to use to grasp the thorny thistle plants tightly enough to pull them out of the dry ground.

Rarely have almost *all* my gloves failed me - but, the thorny purple thistle weed was a challenge that dared to be overcome!

Any neighbors must have looked at me oddly when I finally figured out how to pull them out without bleeding, as I held them up in the air in my gloved hand exalting in my thorny triumph!

[Danny D.]

Hmmm... I don't know what a "root and stolon" system looks like.

Most looked like taproots - like this:

Or this:

And this:

However, some came out as 'clump' roots - like this:

And this:

PS: It was only half way through the eradication task that I belatedly realized shoving a garden hose nozzle into the center of the plant and blasting the roots loose was the way to go!

[Danny D.]

I didn't see songbirds eating; but I did watch this one bee with interest.

I'm not sure what it was looking for - but it kept digging away on the purple stuff (which is just about the only non-thorny thing):

[Danny D.]

Hi Kay,

I have 5 gallons of concentrated 40-something percent glyphosate, so, I do have plenty to go around ... but what does "heading" mean?

I guess that means to chop off the purple 'ball' at the top?

What about the green balls that look slightly different?

[Danny D.]

At first, I thought lovely thorny plant was a "Purple Starthistle", (Centaurea calcitrapa), which is an invasive weed in the San Francisco Bay Area:

But, now I think it's a Bull Thistle (Cirsium vulgare), which is also prominant in the bay area, based on the fact that this looks like it:

This site says it has a taproot and that "cut flowerheads can still develop viable seed", but I would have no idea how:

[Danny D.]

I think it's a "Bull Thistle" (Cirsium vulgare).

Apparently it only reproduces by seed, but, the seeds must be removed from the area...

Plants from Yosemite Valley that were cut at the root crown a few days after their first flowers appeared and then laid on the ground produced abundant viable seed (Randall pers. observation). Thus it may be important to remove cut stems from the area.

[songbird]

Danny D. wrote: ...

...

no need to pull any of it:

1. remove seed heads/flowers (these go into a hot compost pile or can be thrown away).
2. hit it with a shovel edge to chop it off.
3. dig up the roots and leave them on the surface to dry out for a few days/weeks (until crispy all the way through), using a rake you can knock the soil off the roots or shake the clumps so they are exposed to the sun and air.
4. keep an eye out for ones you've missed.
5. bury it all down a foot or more.

songbird

[Pat Kiewicz]

Heading -- yes, cut off the flowers (purple) and buds (green).

More often seen in the phrase 'dead heading' which is to cut off the spent (dead) flowers on an ornamental plant, so it does not 'waste' energy on setting seeds.

[Pat Kiewicz]

The part you cut off is still alive, for a while. The last bit of energy and moisture in the cutting is given over to finishing the development of any viable seeds.

It's not only thistles that are capable of this. I suspect that most of the plants that have this ability act like weeds in other ways, too.

[Danny D.]

Well, I've read about a dozen pages on the bull thistle, and, it seems relatively easy to control (as long as you don't let it get to the level I did).

Apparently mine are two-year old plants (for the most part).

The yearlings only form low-lying rosettes, of which I have a few. These radiating leaves don't produce a stem, so they lay below the (lawnmower) radar, but otherwise don't reproduce.

The second year is when they produce the flowers, and then when they flower, they die. The seeds don't appear to travel all that far but they have an amazing germination rate (over 90%) so I'll be weeding them for a few years to eradicate them.

The flowers are a rich nectar source, hence my bee will go hungry in the next few days:

[Danny D.]

Thanks for clarifying. I've never headed a plant before.

It seems that the seeds only last about 5 years, so, of the noxious weeds I need to deal with, this one won't be too bad.

It *only* spreads by seed, and I can prevent that with heading.

Plus, it shows itself a year earlier (as the rosette), so I

*should* have pulled them last year - and then they would never have gotten to this second-year stage.

Apparently I can eat the stems, but, the kitchen already has mustard plants all over the counter, as I experiment with what is said to be tasty and what is not:

[Danny D.]

This says we can eat the roots, but, they contain "inulin", which is apparently a non-digestible starch.

It also says the flower buds, young flowers, stems, and leaves can be eaten. Even the seeds can be eaten, roasted on a grill.

This one says the inner bark can be used to make paper:

This one says the flower base can be eaten like an artichoke:

This one says the purple flower petals can be used as chewing gum and the seeds can be used to make a light oil:

For the Scots out there, it's the national emblem of Scotland (because a barefoot invading Viking stepped on one, alerting them to the attack).

[Natural - Smoking Gun - Girl]

Wouldn't shoveling it at the root base first to loosen it help out?

[The Daring Dufas]

Danny, I want to complement you on your picture taking. It makes it much easier for others to understand what you are writing about and you really seem to enjoy photography. I have to Email lots of photos of the work me and JH do to the service corporation we do work for and I've gone through two inexpensive digital cameras this year. I'm going to see if I can find a darn rubber coated drop resistant camera. ^_^

TDD

[Danny D.]

Thanks. I've been on USENET for decades and on forums for years, and I believe in being responsive, providing enough detail, and that a picture is worth a lot more than a description.

BTW, along those lines, I took my black widow spider to a friend who is writing a book on how to photograph hard-to-photograph animals, and you should see the excellent closeups he got of her red hourglass belly and her spinning silk threads out of (her belly?).

Mine are on the top; his are on the bottom:

Now he wants all my rattlesnakes!