A friend came to visit us and after eating homemade Belgian waffles I suggested I take her and my family to Pod Meadow, which I had discovered on a walk with Transition earlier in the week. The weather was a balmy 55F and only partially overcast.

Pod Meadow is an amazing conservation area in my town that is a hidden gem, “a sleeper,” the town naturalist calls it. It is 25 acres. You park the car on a busy road – no less than the old Native American Great Trail, which became a major highway in the colonial era and is now Old Connecticut Path, or Route 126. You walk through someone’s yard, and then, suddenly, this:

Amazing, the sudden dip toward the Pond and the lack of tangled shrubs under the stately trees – mostly beeches, oaks and some pines and spruce – which allows you to see right through. It gives the open and clear feel of a maintained forest, much like, I presume, the forests in the time of the Native Americans, who used to set fire to the underbrush to make hunting and travel easier.

In this forest the maintenance is done by the beavers. I don’t have the skinny on the beavers yet, but there seem to be many of them and, some worry, too many. They have dammed the Pond so that now the water reaches higher, inundating old trails and making what used to be a vernal pool (first water body in the picture above) into a part of the “full-time” pond.

The beavers clear the forest by doing this:

Amie couldn’t believe it. Imagine chewing through a whole tree with your teeth! There is more beaver handy toothsome work behind her: the beavers apparently like beeches the most and in this spot most of them were stripped of their bark at beaver height. It is amazing to run your finger over the scrapings. To me it is like touching the wild. Here’s an even bigger tree (an oak) being worked on:

And some more beeches:

We speculated that there must be some system or plan in their activities. Perhaps they are working up to a moment when they will tip one tree and it will take down all the others, like dominoes, in one great bang! Then they’ll have a party, say “our work is done here,” and move on.

For the moment they’re at home. This is their lodge. No sign of the inhabitants.

Seeing all this is so awesome to me, and I am eager to learn more about these animals. I’m also fascinated by the geology of the place, which is, like so much of New England, dominated by the 50,000-year-old glacier that started to retreat 15,000 to 16,000 years ago. I sometimes dream about that glacier.

Today was about Amie. At first she didn’t want to come but the moment we arrived she started running and jumping, suddenly free and wild herself. She had climbed onto this great downed oak before we knew it and DH had to scramble after her.

She also really wanted to walk on water:

She was upset at the end and I didn’t know why. She said she had “wanted to have more adventures and all we did was walk around and chat!” I will take her back after school some day and she can show me what it is that she wants to do. We can also take our journals and draw or write.

We are reading the Finn Family Moomintroll which another friend gave her and perhaps she has that landscape in mind and the adventures of Moomin and his curious friends. I can certainly understand her. When I was a kid I was always pottering around in the overgrown area (now a nature reservation) across from my parents’ house, pretending to be the last kid left on Earth, losing my boots in the bog, coming home with leaves and mud in my hair.

I would have gone on that tree too! I may still.

John Root conducted an Edible Wild Plants Walk at the organic Lindentree Farm in nearby Lincoln yesterday evening and I was there. I learned that that weed, of which I pulled thousands from the old compost heap, is Lamb’s Quarters, that it is absolutely yummy and nutritious and grew itself for free and without my care or attention (but I already knew that). And I ate not a one. They all went into the (new) compost, though, so eventually I’ll eat them, but still.

The entertaining  and knowledgeable John Root introduces us to Jewelweed

Today I pulled several weeds from the strawberry patch. I spent some time with one of them, Botany in a Day, and Amie’s loupe and discovered it is a Mallow, probably Cheese Mallow (Malva rotundifolia). Here’s the distinctive funnel-shaped five-petaled flower with a column of stamens.

Mallows have 3 to 5 partially united sepals and often several bracts. This one has 5 sepals and 3 bracts (smaller sepal-like modified leaves):

My plants has these beautiful round leaves – hence my hunch that is is rotundi-folia:

The ovary of the Mallow matures as a capsule, or a “cheese”:

Matured flower next to immature flower:

The Mallow is mucilaginous or slimy when crushed and contains pectin. The marshmallow we roast over the fire used to be made from the roots and seeds of the Marshmallow (Althaea officinalis – which comes from Europe and which I purchased and have thriving in my herb garden) and our indigenous Malva can be used to make marshmallow too.

Because the Mallows are so slimy, they are a great external emollient and an internal demulcent and expectorant. Roots, leaves, flowers and seeds (cheeses) can be eaten and are rich in calcium and iron.

I’ve always been fascinated by evolution in all its aspects (or at least those I can comprehend) but, I realize now, for different reasons than some if not most people. Usually people’s  interest in evolution is in a theory of advancement, even perfection. These people reach for the light, like the  plants that developed vascular systems to grow upright, up toward the sun, and left the primitive, non-vascular mosses behind, eventually shading them out.

The Asters, the dandelion among them, will appeal to them. They are some of the most advanced plants in on earth, well-adapted to new circumstances, and newer.

I’m not charmed. The Asters are to me but the first and the least interesting step on a long ladder leading back, down into time. Primitive, that’s what I want to  see. The older, the more fascinating. So, among the flowering plants, I like the buttercups (Ranunculus).  The buttercups are (give or take) at least 34 million years old (*). I am honored to have one of these awesome survivors in my garden.

Now, my buttercup is not nearly as ancient as these guys:

I don’t mean the squash – though the Cucurbitaceae as a family are  even older than the buttercups, originating in the Late Cretaceous, some 60 million years ago (**). I mean the mushroom, as yet unidentified. A mushroom is the fruiting body of a fungus, and fungi like these made landfall in the Cambrian, around 500 million years ago, long before plants did.

These mushrooms are growing, by the looks of it symbiotically, in the bed I fertilized with horse manure last Fall. It is, by the smell and feel of it, my richest bed, but we have mushrooms above ground and mycelium in it (or, I should write, through) it all over our property. It’s nothing to be alarmed about. Almost all plants partner with fungi, and 80% of plants couldn’t survive without them. It was probably this association that made it possible for plants to come ashore in the first place, between 440-510 million years ago.

I’ve found the same combination on some of the seedlings’ peat pots (the pairing here is some other, unidentified fungus, with a pepper seedling).

How awesome is it, to have evolution – time itself – growing right there in your vegetable garden, and to know it, and to be able to tell some of that story.

(*) see here for a marvelous ladder.

(**) more ladders here.

My copy of Botany in a Day by Thomas Elpel arrived yesterday and I am hooked. Clearly written, humorous but without fluff and to the point, tightly structured, and beginning in the beginning and ending with the end. Just the way I like my books on the structure and evolution of plants. I plan to learn a lot!

That’s it for today. Just a plug for this wonderful book.

Every Spring, since we’ve been here, we’ve had a Robin’s nest near the house. That’s why we call the place Robin Hill – plus it has a little bit of Robin Hood in it.

Year One (2008) they chose the rafters of the carport and Year Two they chose the nook next to Year One’s nest. We never understood why they do this, as the carport is a relatively busy place. Each time we would walk in or past, the Robin on duty would take off with a great flutter of wings to perch on a nearby tree branch from which to scold us until we left.

I know that Robins will return ever year but will never re-use a nest, and now it seems that they won’t even use the same space. In anticipation of their return I had moved the two old nests so they could go there again, as they seemed to like it so much. Instead they chose to move into the Japanese Andromeda that is right next to the mudroom entrance and the guest room window. An even busier place!

We now use our other (main) door – which leads straight into the living room – as often as we can, and try to tiptoe around, but it is difficult not to disturb them. The frantic escape from the dense bush is even more alarming what with all the leaves flying off as well. Still, it makes for great observation. Maybe we will install that webcam.

So far there are three beautiful blue eggs in the nest (Robins lay one egg a day and usually stop at four) — ah, that was based on my quick peek yesterday: today there are four!

And one wary Momma Robin (it’s usually the females who incubate the eggs).

There must be a bird’s nest in our shed as well. Each time we walk in there is a loud chirping, but we haven’t located it yet, so I can’t say what it is. Maybe the wrens, who always hang out in that shed.

The other night my birdwatching neighbor came over to tell me there are is Barred Owl (Strix Varia) nesting in the trees behind our property and that I should listen for its calls. That evening, there it was, that typical “Who Cooks For You” call. By the time we got the mike out there, the call had changed to:

owlhoot1 and owlhoot2

(We are thinking of placing a mike on top of our roof, and whenever we hear something – the fisher cat, or the owls – we plug it into a laptop and record it. Yet another scheme here on our Hill!)

As we listened that evening I said to DH how wild it was, how I love how wild this place is (I wrote about the contrast with Europe here). DH remarked that surely an owl is not that wild – maybe he had jaguars in mind, and grizzly bears.

I replied an owl is pretty wild. What do I mean by wild, or wilderness? It took me not a second to answer it: Wild is Old.

That owl up there, high up in the tree, in the wind and the total darkness, is calling for a mate as it has been calling, with that exact same call, for millions of years.

Compare this with us, humans, our many, many languages, our many more ways of wooing, of saying “I want you” and “here I am”. And we’re changing  those every thousand years, every generation, every day. We are constantly adapting, transforming, cultivating, culturing.

The owls, the fisher cats, the bees, they don’t change. They stay wild. Their wild ways work for them as they did millions of years ago. That is wild. Wild is Old.

I heard the sound again and this time we ran out to record it. It was further away and it sounded a little different from last time – less catlike – but though the “words” are different, the voice seems the same (to the one in my memory). In any case, if you can tell us what it is, if not a fisher cat, let us know!

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You guessed it: it’s time for another episode in the Calcium in the Soil and Plant series! Take heart: we’re getting close to the end (maybe only one more part to go?). Actually, it took me so long to post on this again because this one took me a long time to figure out. If you want to brush up on the previous parts, check out this page.

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Part 8. Selective Nutrient (and Water) Uptake by Roots

Nutrients arrive at the root surface in three ways:

  1. The first of these is root interception. As roots grow, they make direct contact with nutrients. This mechanism is less important because roots come into direct contact with only 1-3 percent of the soil volume exploited by the root mass. Mycorrhizae – fungi that form a symbiotic association with plant roots – can increase the surface area that roots can extract nutrients from. Calcium and magnesium, because they are so abundant, are often intercepted by root contact.
  2. The second mechanism is mass flow, wherein plants, sucking up water (through the various pumps and pulls discussed in the previous part), also move the nutrients that are dissolved in it. Especially mobile (free) nutrients are “attracted” in this manner: nitrate-nitrogen, chloride and sulfur, which are never absorbed by the colloid and thus always exist in solution, and calcium and magnesium, which are held only loosely to the colloid. The drier the soil, the less mass flow.
  3. The third mechanism is diffusion, by which ions in the soil spontaneously move from a point of higher concentration to a point of lower concentration (like in osmosis). Diffusion happens in the soil because the immediate root area, once it is depleted, has a lower concentration of the nutrient ions. Immobile nutrients like phosphorus and potassium, which have a low solubility, are strongly held by the colloid, and are only present in small concentrations, reach the root through this mechanism. The soil porosity is important here: smaller pores will block diffusion.

The last two mechanisms are the more significant mechanisms of nutrient uptake. Which one is predominant depends on the nutrients, the amount of water in the soil and the physical conditions (e.g., crumb structure) of the soil which dictates the movement of water through it.

Nutrients (especially immobile ones) then need to be wrested from the colloid by an ion exchange – the cation exchange capacity (CEC) talked about on a soil test. As we saw, the positively charged nutrient cations are held to the negatively charged colloid by a small electro-magnetic bond. When the root hairs release hydrogen ions (H+) and these come into contact with the colloid, they take their places on the colloid, breaking or weakening the colloidal-nutrient bond. The nutrients are knocked free and this makes them more available to be taken up by the root hairs.

Once the nutrient has arrived at the plant root surface and has been made available, the root needs to take it in: the nutrient-ion needs to travel from the root’s exterior to its interior.

As we saw in Part 7, the membranes of the cells making up the epidermis and the endodermis of roots are semi-permeable. This means several things. First, roots allow movement in, but not out, which allows osmosis to take place, by which water is taken up by the plant roots (cf. Part 7). Second, they allow only small solutes in, so they are impermeable to the large molecules of organic solutes (more about that in the next part). Third, some small solutes are allowed in, but others are not: plant roots are selective about their food.

It is the last aspect that interests us here. The uptake of the nutrients (as well as sugars and amino acids) by the roots is selective because of two main features:

  1. First, the root membrane has channels that are ion-selective: one type of channel will let through only phosophorus ions, another fits only calcium ions, or potassium or nitrate, etc. Think of the toddler’s toy: the box with the star and pentagon and circular shaped holes into which only the star and pentagon and circular blocks fit. The root too is constructed like that.
  2. The actual ferrying through these channels is done by ion-selective carriers: so-called coupling proteins that are embedded in the membrane of the root cells and that only react with specific ions, passing them on. Different plants require different amounts of nutrients, and so they will have different types and densities of ion carriers on the surface of their cells. These ion carriers are also most numerous on the surface of root hairs and root tips, which shows that roots are the main conduit for nutrient uptake in plants.

That explains the root’s selection of particular nutrients. Now, how does it select their quantity? How does it say, that’s enough?

As for water, its protein carrier is the aquaporin. Aquaporins are embedded in the cell membrane, forming transmembrane pores that conduct just water molecules. They prevent the passage of ions and other solutes by a filter (the ar/R filter) of amino acids that bind only water molecules and let them in (single file), while excluding all other molecules. When there is a lack or an excess of water, a gating mechanism changes the shape of the aquaporin so that it blocks the pore and stops the water flow. These gates can fail and an excessive amount of water can break the gates, as it were, and “drown” a plant.

Nutrients like calcium ions are taken up by different transmembrane protein carriers, which actively transport them, that is, they require energy to do so, because they have to pull in ions against their concentration gradient. For instance, there’s a good chance the root cells already have a higher concentration of calcium than the soil in the root area, but it might still need more. The energy required comes from a part of the cell (called the ATP, a nucleotide). If the plant has enough of a nutrient, it can simply stop drawing on the energy source. Also this mechanism can fail, and an excess of nutrients can lead to a toxic overdose and kill the plant.

So, however well-equipped roots are to select what the plant is in need of, it is still up to us, gardeners, to know how much of what a certain plant in our care needs and how much of it is present in our soil.

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Next up, nutrients not in mineral but in organic form, and how those can make it into the plants. Yes, the egg shells. Finally!

Friends are coming to visit for a couple of days, and I doubt I will have the time, or the inclination, to interrupt the fun we always have to post here. But before I go, a few notes:

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Turns out that the bobcat I heard a couple of weeks ago was most likely a fisher cat. My neighbor saw one crossing the street this morning and immediately fired off an email to let me know. And it clicked, because Suldog had raised this possibility in his comment to my post. Apparently fishers make that haunting sound during mating season, though they’re also know to make it when they’re trapped or attacking. No bobcat, then, but pretty wild anyway!

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I’ve signed two petitions in the last two days.

  1. One for allowing chickens in Cambridge, Mass. (there’s a blog article about it here, and the petition is here).
  2. The other for allowing the sale of raw milk by a dairy farm in Framingham, Mass (about raw milk in Massachusetts, click here, and here, and to sign the petition, click here).

There’s a Food Revolution and I’m on it!

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I totally missed the “Focus on Feeders,” which the Mass Audubon Society organized this year on 6 and 7 February. But I am thinking about sending one or two photos to their amateur photo contest. Here’s a selection (click for larger):

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dscf3770 Downy and Hairy Woodpecker (c) Katrien Vander Straeten, october 2008

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They are: Black-Capped Chickadee, Tufted Titmouse, Rose-Breasted Grosbeak, Downy and Hairy Woodpecker side-by-side, female Northern Cardinal and Red-Breasted Woodpecker (photo taken yesterday).

I like the first two because of their wintry atmosphere: the birds seem cloaked in the snow-laden sky. The Grosbeak was such an exception at my feeders, and I love the color of his breast. The Hairy Woodpecker (the large one) is so darn ugly; even his eye looks scruffy! But it was great to see the two kinds side by side. The female Cardinal gives us such a stern look, and look at the soft colors of her belly. And that last picture is just so vivid.

Do you have any favorites?

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This is already the seventh part in a series on how calcium and other nutrients get into the soil and then into plants. Here we finally meet the plant roots, and investigate how they take up water. Click to read part 1, part 2, part 3 and part 4, part 5 and part 6.

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7. Water uptake through osmosis, turgidity, root pressure and transpirational pull

I’ve given so much attention to the solubility of calcium in water because plant roots can take up nutrients only if they are dissolved in water. Let’s stick with the water for now and add nutrients in part 8. How do plants take up water?

The surface of root tips are made up of epidermal cells (epidermis = outer skin) and their extensions, called root hairs, which form a fuzzy band and increase the absorptive surface area and thus the rate of water uptake several hundredfold. These surface cells and hairs draw water from the soil by osmosis (Greek osmos = a push).

Osmosis happens when there is an unequal concentration of solutes in the water on either side of the epidermis. On the outside, the soil water consists mostly of water with a small amount of salts (any dissolved ions – see part 5). On the inside, the epidermal cells contain water with a much larger concentration of salts, sugars and other substances. The water in the soil seeks to dilute the water inside the epidermal cells, and it pushes, through the epidermis, into the root. The epidermal cell membranes allow this free movement, but only in this direction. If outward movement were allowed, this system would not work, and the root would lose its precious salts and sugars.

The water is stored in the vacuole of the cell, making it turgid or swollen. When the vacuole is fully inflated, the water uptake will slow down, because the internal pressure or turgor inside the cell will squeeze the water out to the next cell, and so up into the rest of the plant, to where it’s needed. You see this effect when you water a wilted plant: slowly all its deflated cells are filled with water through turgidity.

This explains what the problem is with excessively saline soils (see part 5). Even if there is enough water in the soil, it is not diluted enough, and so the inequality between it and the water in the root cells is not large enough, to achieve strong osmosis. Even worse, there might be less water content in the soil water than in the root cells, which reverses the direction of the osmotic flow. Deflated of their torgur pressure, the plant will wilt and, if this continues, die.

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Cross section of a plant root
(image from Capon, Brian, Botany for Gardeners, Timber Press, 1990, p.141)

Water constantly circulates into, through and out of the plant. This happens through two specialized vascular tissue systems that run up and down through the entire plant. One is the xylem tissue, which carries water and solutes, and the other is the phloem tissue, which carries mainly organic nutrients, like sucrose. We’re interested in the xylem, which is situated at the center of the root.

To get the water from the epidermis (outer skin) to the xylem, it has to cross another boundary, the endodermis (= inner skin). The endodermis is a second osmotic pump, adding to the pressure (but I’ll return to this one in part 8, because it has to do with how nutrients are taken up). The epidermal and the endodermal osmotic pumps together create root pressure, which moves water (and nutrients) from the root tips to the tips of the leaves, through the xylem.

But just root pressure is not be sufficient to pump water all the way up into the branches of high trees. A second system is necessary for this, called transpirational pull. As the terms suggest, root pressure is a pushing (up) force, from roots to leaves, whereas transpirational pull is a pulling (up) force, from leaves to roots.

Very simply, transpirational pull works like this. Water molecules cohere together, forming an unbroken string or column of water in the xylem, all the way from root tip to leaf tip. When one water molecule is lost at the surface of the leaf through transpiration, or evaporation, the next water molecule is pulled up, along with the whole string of molecules. At the bottom, the roots get to suck fresh water from the soil.

And not just water, of course, but also the nutrients that are dissolved in it. Plants are, however, selective in what nutrients they will allow in: they won’t take up what they don’t need. That in the next part.

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I foresee one more part (Part 8). Maybe two. But I keep an option on three.