Why “Howplantswork”?

The goal of this blog is to explore the inner workings of plants, on which we all depend for our existence.

In this blog, I’ll primarily focus on sharing new information about plant function (a.k.a., plant physiology).

I prefer to approach this subject mainly from the perspective of the life of a typical flowering plant (angiosperm): seed germination, plant development, how plants make a living from day-to-day, and, finally, flowering and plant death.

Along the way, I’ll feature topics of current relevance, such as the effects of increasing atmospheric CO2 on plants, the use of plants to clean the environment (phytoremediation), and the extraction of biofuels from plants.

Ultimately, it’s all about how plants work.

Who Is This Guy?

The author at Purple Haze Lavender Farm, Sequim, WA (Dr. Stout is on the right).

The author at Purple Haze Lavender Farm, Sequim, WA (Dr. Stout is on the right).

My name is Richard Stout, and I live in Bellingham, Washington.

I received a Ph.D. in Plant Physiology from the Botany Department at the University of Washington, Seattle, in 1980.

Since then, after a brief stint as post-doc researcher, I was privileged to serve as a faculty member at Williams College (Williamstown, MA) and Montana State University (Bozeman, MT). Over the years I’ve enjoyed (mostly) teaching biology, biochemistry, botany, and plant physiology.

While at MSU, I was fortunate to be able to do some plant-related research in Yellowstone National Park (see here, for example).

In May, 2008, I said goodbye to academia, and so now I have time to pursue other interests, such as this blog.


dave1This weblog is dedicated to the memory of Dr. Dave Rayle, who was both mentor and friend.

Dave was a member of the faculty in the Dept. of Biology at San Diego State University for many years.

He, along with Prof. Bob Cleland at the University of Washington, investigated how the plant hormone auxin stimulates plant cell growth.

During the course of this research they developed a theory known as the “Acid Growth” theory (PDF), which has become one of the fundamental concepts in plant physiology and developmental biology.

Basically, this theory explains how auxin stimulates the elongation of cells in young stems. It turns out that this is also key to both phototropism and gravitropism in plants.

And the acid growth theory may also have implications beyond the plant hormone auxin, since the acidification of the cell wall may also play a role in the growth of other walled cells, such as in fungi and protists.


Dave was also an avid (rabid?) fisherman.

He rarely passed up any opportunity to go fishing, whether for winter-run steelhead during blizzards on the Skykomish River in Washington state or for rainbow trout during summer float trips on the Smith River in Montana.

Dave died in June 2001 at the age of 58, soon after he retired from San Diego State University. (Fitting eulogies were written for Dave by his friends and colleagues Bob Cleland and Ken Johnson.)

Dave Rayle was both a scientist and fisherman extraordinaire.

It was my great good fortune to have known him.

And as he was a great teacher, as well as a great scientist, this site – all about how plants work – is dedicated to him.



  1. Thanks for this well designed and informative blog based on scientific facts.

    May I suggest that you reverse the order of the comments on this page. it will show the quick reader that the site is alive! Of course for the other pages I guess the chronological order is most appropriate since they are usually a form if discussion. Though someone following a specific post will want to see the latest addition on top. Not an easy choice :l

    Great day to all

  2. GREAT SITE!!! thanx!

  3. GREAT SITE!!! thanx!

  4. Great blog. Flash from the past! Send me an email….dc

  5. Excellent site – lots of good information. I seem to be arguing almost incessantly with people about the misting of house plants to raise humidity. Can you point me to a study that has measured the actual humidity levels after various amounts of misting?

    • Are you aware that there’s a danger notice on gmail, warning not to click on any links, etc? I got to your site by entering your address in my browser. Anyway, still reading your blog – pretty cool.

      • Thanks for the comment.
        I checked howplantswork.com on the Google Safe Browsing website: no problems.
        So, I guess it was just some sort of glitch.

  6. Can you help me with this question?
    If root hair cells take up water from the soil by osmosis, what would you except to happen if so much nitrate fertiliser was put on the soil that the soil water became a stronger solution than the cell sap of the root hairs?

  7. Hi Richard,

    Hi there,

    The link you have for our app (Garden Compass) in your Cool Tools post does NOT link to our app. It goes to a totally different garden app.

    Here is the correct link:


    would super appreciate it if you are able to change it….

    Please feel free to call me if you have any questions.

    thank you so much!

    1660 Union St. #301
    San Diego CA 92101
    office 619-239-2202

  8. Hello! I was just looking for any information about the relationship between moon and plants and reached your web site. I’m very impressed by what you have written because I could easily understand your English and second your information is very academic.
    I’ll try to read the references and continue my study!
    Thank you so much, and I’d love to visit your site now and then.

  9. christine hornhiot


    I noticed that you shared http://www.wired.com/2015/02/new-gmo-crop-controversy/

    I thought it was pretty great myself and it gave me some inspiration in creating something similar the other day: http://brightmags.com/does-organic-mean-non-gmo/

    Just wanted to give you a heads up about it πŸ™‚

    If, you think it is good enough, can i request you to pls share it with your followers.


  10. pardon the misspelling in previous reply—should be “effective”

  11. OK—so plants convert carbon dioxide into sugars and not directly into oxygen—since we are concerned with the amount of carbon dioxide pumped into the atmosphere through emissions, etc. is there any way that photosynthesis on a mass basis can be efeective?

    • Yes. Two ideas. Stop chopping down tropical forests. Fertilize parts of the ocean with iron to stimulate photosynthesis in phytoplankton.

  12. Sarah (Fetzek) Tabor

    Hello Professor Stout,

    I was just wondering how you are doing and thought I would try to track you down on the www. I look forward to reading more on your blog! I hope you are enjoying retirement. This story got me thinking about the good old days in YNP and how I wish I could’ve pursued the bryophytes a bit more….

  13. Pingback: On track with Plant Trek | AoB Blog

  14. Hello professor,
    I am a U.S. trained economist, & although I don’t have a question; I only wanted to congratulate you on this highly educational and entertaining site;
    I believe that every once in a while, we all need a tab on the back, and although I belong to dismal science or discipline! ; Yet I will continue to be a junior budding botany enthusiast (as I continue to find correlation with economic life); In a word, simply I think what you are doing is just wonderful, and I am more and more fascinated with this kingdom as much as I am sure you are still obviously fascinated with plants.
    Best regards

  15. Greetings Professor Stout,
    Love your blog. Always something uniquely interesting to discover. I visit often (via Twitter) whenever you post. I have a question about how to scientifically describe the relationship between two vascular plants that are fused. Twice in the past few months I’ve come across a smaller tree growing from the trunk of a different more-mature species. Below are two links to pictures I recently took. The first is a picture of what I believe to be California Privet (maybe: Ligustrum ovalifolium Hassk) growing from the trunk base of a California palm (http://www.lifeandleaf.com/leaf/parsitic-plant-relationships/). The second is a Camphor sapling growing from the primary branch bark crook of a huge Canary Island Pine (http://www.lifeandleaf.com/leaf/tree-as-parasite/).

    My guess is that a bird-passed seed becomes trapped in the frond skirt of the palm, and in the joint of the branch bark on the CI pine. The seeds germinated and tapped into the Xylem somehow. The question I have is, “is the relationship epiphytic or parasitic?” I’ve seen described both ways on the web, but it seems to me parasitic. Or maybe I am waaay off base. Any clarification would be greatly appreciated.


    • Robert,
      Thanks for your interesting comment.
      I’d say your interpretations are quite reasonable, though I don’t have much experience with such phenomena. My experience with epiphytes includes orchid living on the branches of tropical tree species in the tree canopies in cloud forests. And I remember that mistletoes are considered parasitic plants.
      What’s the precise difference between an epiphyte and a parasite?
      My working definition is that if the host plant is merely a platform for the dependent plant, then the dependent is an epiphyte.
      If the the roots of the dependent plant penetrate the host, then I’d say it was a “parasite”. If the dependent’s root cells can generate water potentials that are more negative than the host’s adjacent cells, then water will flow into the “parasite” from the host via simple osmosis.
      If the dependent can somehow tap into the host’s phloem, then I’d say it’s likely a “more serious” parasite. Though, if the dependent has green leaves, and thus produces sugars via photosynthesis, does it actually contribute sugars to the host via this connection?
      As you can appreciate, it’s difficult to simply classify all the different instances of plant-plant interactions.
      For example, some scientists are convinced that there are complex connections among plants via subterranean fungal mycorrhizae. So, which are the hosts and which are the dependents?
      Sorry…..I don’t think I’ve clarified much, if anything.
      I’ve bookmarked your website and look forward to reading it often.

      Best regards,

      • Professor Stout, or may I call you Rich?
        Thank you for your response. Since emailing you my initial question I scoured the Web for a few more hours and it appears that I was way off base on the epiphytic guess. You are right, they are parasitic relationships as the parasite receives water/nutrients through a tapped physical connection via the physiological bridge, (which I learned is termed: haustorium) and epiphytes grow on plants (e.g., orchid roots wrapped on/around tropical tree branches for optimal canopy water/light access).
        A plant parasite (to be called one) must physically connect its vascular system to at least one of the tissues of the host. Since both host plants (in my pictures) are large and pulling much water, and the parasites are leafy, I think your guess that Xylem is providing water and the rest is left photosynthesis. But who really knows. Still, what an interesting thing to see. You would think the host would force the invader out for survival, but I suppose the small size of the invader can be viewed as some sort of sucker fish on a big whale. Just getting a taste but not intending to kill.

  16. Hello,

    I forgot to mention the webaddress in the previous mail on which you can find my theories:


    kind regards,


  17. Hello,

    I really liked reading the articles on your website. It was really interesting. Not only the content is good, but also the way it is presented. I have similar interest as you. I also studied biology, obtained a phd, did reseach and quited reasearch… And since one month I also have a blog on which I write my ideas on plants. My blog is a little different from yours. I have some ideas I want to share on the evolution of plants. I try to explain the biochemistry and architecture of plants by looking/trying to understand the evolution of the plant. I invite you to read my ideas. (at the moment, there are only two of my theory published online. A third will follow in one or two weeks). I would like to know your opinion.

    kind regards,


    • Stijn,

      Thank you very much for your kind remarks.

      I will be sure to visit your website and read your posts regarding plant evolution.

      Happy New Year,


  18. Hello Dr. Stout,
    My name is Jacob and I am working to put together a quarterly magazine for citizen scientists. Would you be interested in putting together an article related to getting started with plants?

  19. yeah! BIG HELP! hehe
    Mushrooms are a tipe of fungi, seaweeds are algae, mosses are bryophytes and ferns i guess are seedless vascular plants?
    I think i get it better now! πŸ˜‰

  20. Hey!! It’s me again!
    I have a different question now. Do you know what are the major differences between the life cycles of angyo/gymnosperms and the life cycles of Bryophytes, algae, fungi and seedless vascular plants?

    Once again Thank you for your help! πŸ˜€

    • Hey, Pilar. Welcome back.

      A nice wiki-page that answers your question is here.

      It’s easy, however, if you are familiar with some common examples of “bryophyte” and “algae” and “fungi” and “seedless vascular plants”. Are you?

      Hint: You’ve probably seen mushrooms, seaweeds, mosses, and ferns. But which of these belongs to which group?

      Anyway, these guys don’t produce seeds, right?

      But angios and gymnos do! (duh!)

      This is pretty obvious, but another big difference has to do with diploid versus haploid organisms. The humans and most flowering plants that you see are diploid. But the bryophytes and fungi that you can see are haploid. (This is a big old clue to answering your question.)

      Figure it out yet?

  21. Thank you so much! you answer in such an interest way! hehehe I was thinking that C3 plants would have a greater challenge with global warming than C4 plants… definetly CAM will be favored… Thanx again for your help! Great blog! πŸ˜€

  22. yeah, know the basics like the photosynthesis, the places where they can be found, the weather, etc. I know that C4 and CAM plants are more “alike” and that C3 plants would have a greater impact with the global warming.

    • The answer to your question is complex, and people don’t really understand plants and plant ecology well enough to make accurate predictions. And why it’s referred to as global “weirding” also reveals our uncertainty regarding how increased atmospheric CO2 will affect Earth’s climate. But we can still try to make some “educated guesses”. (see http://howplantswork.wordpress.com/category/co2/ for example)
      One thing is certain, however: atmospheric CO2 will continue to increase. Probably double in your lifetime. Earth hasn’t experienced such high levels of atmospheric CO2 for hundreds of millions of years. The fossil and geologic records of this period can give us clues as to what we can expect. Briefly, the planet was hotter and plant growth was lush.
      It was lush at least in part because plants had higher amounts of CO2 to use for photosynthesis. At this time, there were no C4 plants. ( http://www.palaeobiology.org.uk/projects_05.htm ) Why not? They didn’t arise until Earth’s atmospheric CO2 decreased. Plants were (still are) “gasping” for CO2 – much like you would be gasping for O2 on the top of Mt. Everest. C4 plants use a specialized leaf structure (Kranz anatomy) and an alternative enzyme to RuBisCo to capture CO2 and then transfer the CO2 into “normal” C3 photosynthesis. This way, they thrive at relatively low levels of CO2 compared to C3 plants. (So, why don’t C4 plants rule? Because they don’t do well at cool temps, that is, outside the tropics.)
      Fast forward to today, with ever increasing levels of CO2. C4 plants are losing their CO2 advantage and in some places are already being displaced by C3 plants.
      How about the likely effects of climate change, mainly more episodes of heat waves and droughts?
      In this case, CAM plants may have the advantage. Why? They’ve already adapted to desert environments. They are C3 plants. (Yes, C3!) They simply use an enzyme to capture CO2 carbon at night (stomates open!), store it as a 4C organic acid malate overnight, and use malate as carbon source during daylight to do C3 photosynthesis (stomates closed to conserve water).
      Bottom line: C4 plants may decline; C3 plants may grow more lushly; but increased incidents of heat and drought may favor CAM plants.

  23. Hi!! IΒ΄m a botany student and I really enjoy your articles!
    I was wondering if you knew the the effects that global “weirding” can have on C3, C4 and CAM plants.
    Thank You very much!

    • Hi,

      I’m glad that you enjoy this blog.

      The likely effects of “global weirding” on C3 plants will probably be significantly different than those on C4 and CAM plants.

      However, my answer to your question won’t make much sense to you unless you know how C3 plants differ from C4 and CAM plants. And also how C4 plants differ from CAM plants. Do you know? If so, let me know, and I’ll be happy to try to answer your question.

      Thanks for asking, by the way.

  24. Hi. I’m from the Philippines and find your articles useful. I’m an agriculturist. Can you enlighten me or do you know anything about differential cellburst extraction. Thank you so much.

    rey D

  25. Hi, your site is fantastic! Could you do some info on bonsai plants? I’m interested to know why and how a maple (for example) only grows tiny leaves when clipped to bonsai. Why don’t they just grow normal sized leaves on a tiny trunk? How do they know? Weird questions, I know, but interesting don’t you think?

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