Monthly Archives: July 2018

Botany lab/rant of the month: that’s a magic beanstalk, not a soybean

In chaotic times, there are moments when you just have to take comfort in order anywhere you can find it. Katherine reviews some basic plant growth rules and takes a major company to task for undermining botanical literacy.

Would you buy milk from a dairy whose smiling cow mascot had an udder perched on top of her head? Would it bother you to see waiving teats where her ears should be? What if the unsettling image were wrapped in a lyrical ode to ungulates and to the steadfast farmers who rise before dawn to tap into “all that mammalian goodness”? Would a Holstein hagiography be enough to distract you, or would the contrast between carefully crafted ad copy and a negligent disregard for bovine biology trip your bullshit meter?

I think about this every time I buy soy milk made by one particular giant of the non-dairy milk industry. Normally I make my own soy milk – it’s cheap and fast and delicious – but sometimes life intervenes and I have to go with convenience. At my favorite local grocer, that means buying this brand. You might think it’s the gellan gum and the “natural flavors” that offend me, but really I just can’t get over the carton.

Have you ever really thought about the magic of plants?” the carton beckons. Well, yes! Yes I have! Like me, these producers have “been rooted in plant power for over 20 years.” Wow, we have so much in common! I am invited to enjoy “all that leafy goodness” and call them “plant-based, plant biased or just plain plant-prejudiced.” No plant blindness here, right? 

Except for this, the botanical version of a cow with an udder on her head and a tail growing out of her chin:

Someone's wildly inaccuarate idea of a soybean plant. the brand name has been obscured to protect its reputation.

Someone’s wildly inaccurate idea of a soybean plant. The brand name has been obscured to protect its reputation. Click to enlarge.

Judging by the edamame pod randomly stuck onto a stem, this altered photo is supposed to represent a soy bean plant (Glycine max). The words below (“Discover the power of plants at [redacted].com”) almost promise botanical accuracy. Yet, for comparison, here is an actual soybean plant, with its trifoliate leaves and bushy growth habit:

Soybeans in Warren County, Indiana

A soybean plant growing in Indiana.

Not only is the image on the soy milk carton clearly not a soybean plant, but the chimeric little sprout violates basic patterns of plant construction. When I showed the carton to my class this spring, the students were all over it with fervor and a sharpie.

Why it matters

There are many extremely important and urgent challenges facing humans and other organisms all over the planet right now, including some negative social and ecological impacts of soy and the potential for new tariffs on U.S. soybeans to make these worse. So why direct righteous ire against the photo on a carton of soy milk? First of all, what biology teacher (or parent or anyone) wants to see inaccurate or misleading images, especially if they appear every single morning on breakfast tables across the country? Second, at the risk of overstating my case, I believe that someone made deliberate choices about both the text and the image on this carton in order to evoke health and sustainability, but that these choices actually expose indifference toward the plants, the farmers, and the natural world. Similar indifference has gotten our species into a lot of trouble. We all get things wrong, but it’s important to try not to.

How a plant body is supposed to look

The green world is full of gigantic trees and tiny floating plants and delicate vines and cacti and orchids and palms and titan arums. Even if we leave aside mosses and ferns to focus on seed plants, it’s obvious that natural selection has taken a very simple basic developmental program and pushed it in almost every conceivable morphological direction. A common set of plant growth rules accommodates the varied forms of a quarter million or more species – which is astonishing – and yet the graphic designer for this soy beverage company somehow managed to stitch together an oddly improbable plant.

Under the basic developmental program, the set of stem cells (the meristem) at the apex of a growing shoot spins off a series of appendages (e.g. leaves) at regular intervals, arranged along the stem in a regular pattern. Most often, appendages spiral around the stem or occur in opposite pairs. The resulting basic vegetative unit is a leaf (or leaf homolog such as a bract, scale, or spine), the span of stem below it (the internode), and a bud at the place where the leaf meets the stem (the axil). A shoot grows by adding these units in sequence. New leaves continue to expand and internodes continue to elongate for a little while, so leaves near the tip of a shoot tend to be smaller and closer together than they eventually will be. Buds in the axils of the appendages may themselves grow out as branches that reiterate the basic body plan. The result is a modular and potentially nested structure composed of repeated subunits.

Basic flowering plant body plan

Flowering plants (and other seed plants) are built from a series of basic vegetative units, consisting of a leaf and an associated axillary bud and the internode below it. Axillary buds may develop into branches that are similarly built of a series of vegetative units. When plants begin to flower, bracts often develop in place of leaves, and flowers emerge from buds in their axils. Note that this generic plant is not meant to represent any particular species.

When a plant starts to flower, this regular organization does not go away, even if it is modified somewhat. For example, flower clusters (inflorescences) are generally produced at branch tips and along shoot axes where leafy branches would have emerged. And while leafy branches are associated with (subtended by) leaves, inflorescences are subtended by leaf-like appendages called bracts. Inflorescences themselves might transition to a complex branching architecture that differs from the rest of the vegetative plant body, but they still produce flowers in a regular pattern. Because individual flowers are conceptually (and evolutionarily) a bit like branches, they also are usually associated with bracts (Rudall & Bateman, 2010). A notable exception is plants in the mustard family (Brassicaceae); one of the genes that tells a meristem to switch gears and make a flower also suppresses formation of a subtending bract (see summary in Krizek, 2009).

Practically, what this means is that any branch, flower, or inflorescence should be associated with a subtending leaf (or bract, scale, or spine) and that any leaf (or bract, scale, or spine) potentially has a bud, branch, inflorescence, or flower associated with it. The regularity and simplicity of this fundamental pattern of seed plant development gives you a powerful framework for interpreting plants. You no longer have to ask what kohlrabi is; the leaf arrangement gives it away. You can use a combination of clues to distinguish a single compound leaf from a branch. It’s fun.

True, the pattern is not always obvious. Leaves and bracts fall off (although they often leave evident scars), and axillary buds can be extremely small or obscured. Leaves can also be reduced to tiny scales, such as those on a potato tuber. Flowers and fruits of the chocolate tree (Theobroma cacao) appear to emerge directly from an old branch, but in fact they are associated with long-gone leaf axils. And woody plants can produce new shoots adventitiously at their bases or when they are damaged. But we were talking about soybeans, not redwoods.

A magic beanstalk

Returning to the image that set off this screed, I might be able to see it as a harmless, fanciful botanical embellishment if it weren’t for the soybean pod deliberately pasted onto the stem. Surely these plant-prejudiced people could have paused their musings on the magic of plants and simply observed an actual soybean plant. They might have noticed that soybeans have compound leaves with three leaflets and that they grow more like bushes than vines. With a good photo, the artist could have gotten this image right without knowing anything at all about how plants develop. However, the text strongly implies that the central values of the company are rooted in a genuine understanding of plant biology, so I think it’s fair to hold them to a higher standard.

Now that I’ve said my piece, it’s time to take a virtual sharpie to that carton and make it botanically correct. Here’s my version.

Making soy milk at home

Homemade soy milk has many advantages. The beans for a half gallon of soy milk cost about a quarter of what you would pay for a carton at a store. Making your own is also more sustainable: bulk dried beans are less resource-intensive to ship than packaged liquid, you can often choose the source of your beans and how they are grown (e.g. organic from the U.S.), and you can control waste from the process. For example, I mix the solids strained from the liquid milk with salt, nutritional yeast, and whatever spices are handy and pack them for lunch. To the milk, I can add vanilla or not as I like. I can throw some oats or nuts or soy lecithin into the boil if I like.

  • 1 cup dried soybeans
  • water for soaking
  • 8 cups of water
  • dash of salt
  • 1/4 cup of rolled or steel-cut oats or almonds or cashews
  • immersion blender
  • fine strainer or cloth strainer bag

Soak soybeans in a medium saucepan (1.5 qt) for at least 6 hours. If you are using steel-cut oats, almonds, or cashews, soak them too.

Bring 8 cups of water to the boil in a large stock pot. The larger the better to reduce the chance that the mixture will boil over.

Drain and rinse the soybeans and return them to the sauce pan. If you are using rolled oats, add them here.

Pour some of the boiling water over the beans to cover them by about an inch, and immediately puree them with the immersion blender. Using boiling water denatures some enzymes that can cause off flavors, and an immersion blender is much safer than a regular blender for hot liquids.

Pour the blended beans into the large stock pot with the rest of the boiling water. Turn the heat to the lowest setting possible. After about 5 or 10 mins, put a lid on the pot and let it cook for another 45 mins. Add a dash of salt about midway through.

Do not leave the pot alone until it has been simmering without trouble for a while. The mixture has a tendency to boil over and make a huge mess within the first 5-10 mins.

Allow the mixture to cool for an hour or so and strain it. Refrigerate the milk right away.

The remaining solids can be flavored and eaten as they are, stirred into breakfast oatmeal or grits, baked into muffins, etc.

References

Krizek, B. A. (2009). Arabidopsis: flower development and patterning. eLS, 1-11.

Rudall, P. J., & Bateman, R. M. (2010). Defining the limits of flowers: the challenge of distinguishing between the evolutionary products of simple versus compound strobili. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 365(1539), 397-409.