Thursday, August 29, 2013

Answer: Quickly! Poisonous or not?

As you can probably tell, I enjoy flowers--especially the local wildflowers that appear everywhere in the Valley and in the woodlands near where I live.  

So when I saw this particular flower, I recognized it instantly as a member of the Compositae family (this is also known as the Asteraceae family).  That's the family name for flowers that looks like this.  This family includes sunflowers, dandelions, asters, and similar flowers.  Like this one, they all have multiple flowers in a single disk (botanically "composite").

AND (key point) most Compositae flowers and plants are edible; both the leaves, stems, and flowers.   Some common edible composite flowering plants are Lactuca sativa (lettuce), Cichorium (chicory), Cynara scolymus (globe artichoke), Helianthus annuus (sunflower),  Carthamus tinctorius (safflower) and Helianthus tuberosus (Jerusalem artichoke). 

(There are a few Compositae that are poisonous.  The most common is probably burdock, Arctium genus, leaves, which can cause a rash. But even then, burdock roots are good to eat, so it's not really toxic, per se.) 

For background:  The name "Asteraceae" comes from Aster, the most prominent genus in the family, that derives from the Greek word meaning star.  The flower has a clear star-shape. "Compositae"refers to the fact that the family is one of the few flowering plants that have composite flowers growing tightly side-by-side in a center.  

But our challenge isn't to feel good about what the kid is doing, but to figure out exactly what it is.  

In my case, I'd just turn to one of my plant identification guides such as A field guide to Pacific states wildflowers.  These books all have a "key," that is, a linked set of questions about the flower that lead to an identification.  

The questions are like this: 

87a.  Flowers in racemes, spikes, or solitary.  See 88. 
87b. Numerous flowers in heads, sunflower-like.  Each flower tubular (some with outer ray flowers). Compositae.  
In essence, if you answer each question correctly and then follow the numbers, you'll end up at the right flower identification.  

In practice, I end up looking up every other word (what's a "raceme"?), and going up and down the tree of questions until I finally get to one that matches all of the test questions.  

We don't have time for that here.  So... what can we online-searchers do to help?  

There are a couple of ways to do this.  

A. Find an online wildflower identification book.  Typically these cost some money.  As you can imagine, there aren't a lot of free ones available online.  There are versions of various field guides that you can buy (say, on iBooks or Google Play).  You could then just use them to ID the flower in the normal way.  

B.  Search for online wildflower guides specific to the area.  This is the approach I took.  Knowing that there are a LOT of people (besides me) who want to identify flowers, I did a simple search: 

     [ summer wildflowers bay area ] 

This query brings up a number of resources that seem like they might work.  I click on the #1 hit  "Summer Wildflowers on Bay Area Trails" that's on a local runner's club website.  I figure it's likely that they'll have this flower since (as you can see in the above photo) it grows well at trailside.  (Note that this works well for me since I'm local to the SF Bay area.  If you don't live here, or live near another Bay, you'll have to add in something like "SF" or "San Francisco" to get results similar to mine.)

Sure enough, the 4th flower on their list shows up as Hayfield Tarweed (Hemizonia congesta), and it looks a LOT like the flower above.  

Here's what they show:  

I'll also tell you that these flowers (and leaves) DO smell awfully strong.  "Incense" is a nice way to phrase it.  It's definitely strong.  

But this little picture isn't quite enough to be sure.  So I'll do another search for the Latin name given here, Hemizonia congesta.  

As you see, the top 3 results are from the website.  I know that Calflora .org is a massive, high-quality database of flowers and plants of California that was originally started by people in the US Forest Service, and also work with the botanists at UC Berkeley.  (You can learn this by checking the "history" tab on the Calflora site.)  Bottom line:  I tend to believe them. 

I start to get worried, though, when I check the Calflora site.  When I look at the page for Hemizonia congesta, all of the flowers are yellow.  Uh oh.  Is this NOT the right flower?  

From Calflora site.  Thanks to them.

See that link to "more photos on CalFlora" on the lower right?  Clicking on that takes me to another entire page of photos of Hemizonia congesta including the white variation.  It turns out there are lots of subspecies, with color variation as part of the defining characteristic.  

Now we have the answer to the first question:  

1.  What is this plant?   
Answer:  Hemizonia congesta, the "Hayfield tarweed" in a white subspecies variation.  


2.  Is it poisonous or not?  

Answer:  No, it's not.  Rest 

To find out, I did a quick search for: 

     [ tarweed edibility ] 


     [ tarweed poisonous ] 

to check.  The answers come back quickly.  Not only is it NOT poisonous, but the local Indians would eat the seeds, aggressively harvesting them in the fall to make pinole.  Reading a bit more, I discovered that they also would burn over the fields to ensure good growing conditions for next year.  You wouldn't do this if the plant were really poisonous!  

And.. for extra credit... How was tarweed used in early California?  As seen, it's clear that they were sought out and harvested for food.  So I did two searches to follow up on this. 

     [ tarweed Indians ] 

     [ tarweed harvesting ] 

Why [ tarweed Indians ]?  (As opposed to the more politically correct term "Native Americans"?)  Short answer:  Because that's where the content is.  It's useful to sometimes use older terms when searching.  (More on this in another post soon.)  

But in both cases, I was able to find many references to harvesting and preparation of the seeds for food.  

One of the loveliest references I could find is a link to this image of a Pomo woman kitted out to collect tarweed.  (Although apparently she's ready to collect seeds of the Maida flowers, also called "tarweed," which look, taste and smell very much like Hemizonia.)  
This image is: The Tarweed Gatherer by Grace Carpenter Hudson (1865–1937), used with permission of the Grace Hudson Museum, Ukiah, California ( 
The woman pictured is well-known basketmaker Joseppa Pinto Dick (circa 1860-1905), who was Yokayo Pomo, a Native community southeast of Ukiah.

Total search time for me:  About 4 minutes (and then an hour to write this up). 

Search on! 



  1. Dan, no question, your question/your answer, but the tarweed answer doesn't seem to match the picture/description/size/shape in the WE. question, especially the petal shape/configuration.
    just sayin…
    white tarweed
    much different than the first photo in the question WE.. can the fungi query be far behind?
    Hemizonia congesta
    Ray flowers 5–13; ligules 5–11 mm, generally white, generally red- or purple-striped below, central lobe narrow
    petal structure - narrow center petal,wider flanking petals
    blossom eaters of the world unite… but don't poison yourselves.
    gGlass/real timePCC connection/image identification - yeah, that's the ticket…

    1. The first picture you mention (white tarweed) looks a lot like my picture. The second photo you show DOES look a little odd. Interestingly, that image (from CalFlora's photo section) was recently reclassified from Calycadenia fremontii, and I wonder if the reclassification isn't incorrect.  This flower has the 3-lobed petals typical of the Calycadenia family, and not the individually separated petals of Hemizonia.  For a side-by-side image comparing these, please see: side-by-side comparison image.

  2. Hi Dr. Russell!

    I learn a lot again with this SearchResearch Challenge. I knew that the center of the flower had a special name. Now, I know it: "Compositae"

    One question, why you didn´t use this term in your query [ summer wildflowers bay area ]? you tried to avoid self confirmation on the search or it was for a different reason?

    Finally, reading more about this flower found that the white subspecies variation is:Hemizonia congesta ssp. luzulifolia

    1. Why not use "compositae" in my query? I could have, but I wasn't sure if general guides to summer wildflowers would use such a technical term. So I did my first search without it, and it worked just fine. When I add it to the search, I see it slightly degrades the quality of the results. The tarweed is still there, so it's not a terrible move.

      If my initial search had given me a bunch of low quality results, THEN I would have certainly added it in. But I like to keep my first queries on the short side.