Month: February 2020

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The Cedars of Pencils

People interested in pencils have been particularly excited lately about a pencil being made by Musgrave, a 100+ year old pencil company based in Shelbyville, Tennessee (a.k.a. Pencil City). This pencil is especially unique because it is made from the wood of Juniperus virginiana, known commonly as Tennessee red cedar, eastern red cedar, aromatic cedar, and (yes, even) pencil cedar. For anyone who may have been around in the early 1900’s, this wouldn’t seem like anything special, as it was not uncommon for pencils at that time to made from this wood. However, around the mid-20th century J. virginiana was largely replaced by Calocedrus decurrens as the wood of choice for pencil making, and few (if any) have been made with J. virginiana since then. Hence, Musgrave’s new pencil, fittingly named Tennessee Red Cedar, is a momentous occasion.

The Tennessee Red Cedar Pencil

Pencils today are made from a variety of different woods and wood-adjacent materials (see Wopex pencils), each having their pros and cons and each being loved, hated, or something in between by people who care about pencils. However, pencils made from cedar – Juniperus virginiana and Calocedrus decurrens in particular – tend to be among the most preferred. These woods are soft, attractive, rot resistant, sharpen easily without splintering, and take well to wood stain or lacquer, not to mention they smell great. But if you’re like me and you’re interested in plant names and plant taxonomy, you may have already noticed something – the trees these pencils are made of aren’t cedars at all, at least not in the botanical sense.

Calocedurus decurrens, commonly known as California incense cedar (or simply, incense cedar), is a large tree in the cypress family (Cupressaceae) that occurs in western North America, mainly in California and Oregon. It’s known for its drought-tolerance and fire-resistance, and humans have found numerous uses for it over many centuries (millennia, even). Juniperus virginiana is also in the cypress family and naturally occurs in eastern North America. As a pioneer species, it is one of the first trees to colonize recently disturbed landscapes. Its rot resistant wood makes it an ideal choice for fence posts and many other products. Its heartwood has a red-purple color to it, which is particularly attractive, especially when contrasted with its pale sapwood (see photo of pencils above).

General’s Cedar Pointe – a natural, unfinished pencil made from California incense cedar (Calocedrus decurrens)

Both of these species, as well as others that are commonly referred to as cedars, have scale-like leaves and small cones. They are more appropriately referred to as false cedars. True cedars, on the other hand, are members of the genus Cedrus and mainly occur in the Mediterranean region and the western Himalayas. As members of the pine family (Pinaceae), their leaves are needles, which are borne in clusters atop peg-like stems that form along branches. Their cones are large and barrel-shaped and grow on the tops of branches.

So why the common name confusion? This likely comes from the fact that wood harvested from both groups of trees share similar qualities and have similar uses. While there are no trees in the genus Cedrus native to North America, the wood of species in the genera Juniperus, Thuja, Calocedrus, and Chamaecyparis (which are found in North America) have fragrant, soft, rot-resistant wood that makes great construction material for a variety of things, including pencils. The name cedar simply has more to do with the wood than the genetic relationships or morphological similarities among these species.

“Natural cedar” pencils most likely made from Calocedrus decurrens

In addition to their new Tennessee Red Cedar pencil, Musgrave also recently produced a pencil made from old Tennessee red cedar slats that have been sitting in a storage building since the 1930’s. These limited edition pencils are a true throwback to pencils of old. If you write or draw with wood-cased pencils, it’s worth considering the trees they came from. While it’s not always obvious what wood or material a pencil is made of, the story behind “cedar” pencils illustrates that there is more to a pencil than its name alone.

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Read more about Tennessee Red Cedar pencils at Pencil Revolution and The Weekly Pencil.

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Winter Interest in the Lower Boise Foothills

The Boise Foothills, a hilly landscape largely dominated by shrubs and grasses, are a picturesque setting any time of the year. They are particularly beautiful in the spring when a wide array of spring flowering plants are in bloom, and then again in late summer and early fall when a smaller selection of plants flower. But even when there aren’t flowers to see, plants and other features in the Foothills continue to offer interest. Their beauty may be more subtle and not as immediately striking as certain flowers can be, but they catch the eye nonetheless. Appeal can be found in things like gnarled, dead sagebrush branches, lichen covered rocks, and fading seed heads. Because the lower Boise Foothills in particular have endured a long history of plant introductions, an abundance of weeds and invasive plants residing among the natives also provide interest.

This winter has been another mild one. I was hoping for more snow, less rain, and deeper freezes. Mild, wet conditions make exploring the Foothills difficult and ill-advised. Rather than frozen and/or snow covered, the trails are thick with mud. Walking on them in this state is too destructive. Avoiding trails and walking instead on trail side vegetation is even more destructive, and so Foothills hiking is put on hold until the ground freezes or the trails dry out. This means I haven’t gotten into the Foothills as much as I would like. Still, I managed to get a few photos of some of the interesting things the lower Boise Foothills have to offer during the winter. What follows is a selection of those photos.

snow melting on the fruit of an introduced rose (Rosa sp.)

fading seed heads of hoary tansyaster (Machaeranthera canescens)

samaras of box elder (Acer negundo)

snow on seed heads of yarrow (Achillea millefolium)

gall on introduced rose (Rosa sp.)

sunflower seed heads (Helianthus annuus)

sunflower seed head in the snow (Helianthus annuus)

snow falling in the lower Boise Foothills

fading seed heads of salsify (Tragopogon dubius)

lichen on dead box elder log

seed head of curlycup gumweed (Grindelia squarrosa)

lichen and moss on rock in the snow

fruits of poison ivy (Toxicodendron radicans)

See Also: Weeds and Wildflowers of the Boise Foothills (June 2015)

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The first issue of our new zine, Dispersal Stories, is available now. It’s an ode to traveling plants. You can find it in our Etsy Shop. 

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Ground Beetles as Weed Seed Predators

As diurnal animals, we are generally unaware of the slew of animal activity that occurs during the night. Even if we were to venture out in the dark, we still wouldn’t be able to detect much. Our eyes don’t see well in the dark, and shining a bright light to see what’s going on results in chasing away those creatures that prefer darkness. We just have to trust that their out there, and in the case of ground beetles, if they’re present in our gardens we should consider ourselves lucky.

Ground beetles are in the family Carabidae and are one of the largest groups of beetles in the world with species numbering in the tens of thousands. They are largely nocturnal, so even though they are diverse and relatively abundant, we rarely get to see them. Look under a rock or log during the day, and you might see a few scurry away. Or, if you have outdoor container plants, there may be a few of them hiding out under your pots with the pillbugs. At night, they leave the comfort of their hiding places and go out on the hunt, chasing down grasshoppers, caterpillars, beetle grubs, and other arthropods, as well as slugs and snails. Much of their prey consists of common garden pests, making them an excellent form of biological control. And, as if that weren’t enough, some ground beetles also eat the seeds of common weeds.

Harpalus affinis via wikimedia commons

Depending on the species, a single ground beetle can consume around a dozen seeds per night. In general, they prefer the seeds of grasses, lambsquarters (Chenopodium album), pigweeds (Amaranthus spp.), and various plants in the mustard family (Brassicaceae). The seeds of these species are small with seed coats that are easily crushed by a beetle’s mandibles. Providing suitable habitat, avoiding insecticides, and minimizing soil disturbance (i.e. reducing or eliminating tillage) are ways that healthy ground beetle populations can be encouraged and maintained. Ground beetles prefer dense vegetation where they can hide during the daytime. Strips of bunchgrasses and herbaceous perennials planted on slightly raised bed (referred to as beetle banks) are ideal because they provide good cover and keep water from puddling up in the beetles’ hiding spots.

The freshness of weed seeds and the time of year they are available may be determining factors in whether or not ground beetles will help control weed populations. A study published in Weed Science (2014), looked at the seed preferences of Harpalus pensylvanicus, a common species of ground beetle that occurs across North America. When given the choice between year old seeds and freshly fallen seeds of giant foxtail (Setaria faberi), the beetles preferred the fresh ones. The study also found that when giant foxtail was shedding the majority of its seeds, the density of beetles was on the decline, meaning that, at least in this particular study, most of the seeds would go uneaten since fewer beetles were around when the majority of the seeds were made available. Creating habitat that extends the ground beetles’ stay is important if the goal is to maximize the number of weed seeds consumed.

Harpalus pensylvanica via wikimedia commons

Of course, the seeds of all weed species are not considered equal when it comes to ground beetle predation. Several studies have sought to determine which species ground beetles prefer, offering seeds of a variety of weeds in both laboratory and field settings and seeing what the beetles go for. Pinning this down is difficult though because there are numerous species of ground beetles, all varying in size and activity. Their abundances vary from year to year and throughout the year, as do their food sources. Since most of them are generalists, they will feed on what is available at the time. A study published in European Journal of Entomology (2003) found a correlation between seed size and body mass – small beetles were consuming small seeds and large beetles were consuming large seeds, relatively speaking.

Another study published in European Journal of Entomology (2014) compared the preferences of ground beetles in the laboratory to those in the field and found that, in both instances, the seeds of field pansy (Viola arvensis) and shepherd’s purse (Capsella bursa-pastoris) were the preferred choice. The authors note that both species have lipid-rich seeds (or high “energy content”). Might that be a reason for their preference? Or maybe it’s simply a matter of availability and “the history of individual predators and [their] previous encounters with weed seed.” After all, V. arvensis was “the most abundant seed available on the soil surface” in this particular study.

Pterostichus melanarius via wikimedia commons

A study published in PLOS One (2017), looked at the role that scent might play in seed selection by ground beetles. Three species of beetles were offered the seeds of three different weed species in the mustard family. The seeds of Brassica napus were preferred over the other two by all three beetle species. The beetles were also offered both imbibed and non-imbibed seeds of all three plants. Imbibed simply means that the seeds have taken in water, which “can result in the release of volatile compounds such as ethanol and acetaldehyde.” The researchers wondered if the odors emitted from the imbibed seeds would “affect seed discovery and ultimately, seed consumption.” This seemed to be the case as all three beetle species exhibited a preference for the imbibed seeds.

Clearly, ground beetles are fascinating study subjects, and there is still so much to learn about them and their eating habits. If indeed their presence is limiting the spread of weeds and reducing weed populations, they should be happily invited into our farms and gardens and efforts should be made to provide them with quality habitat. For a bit more about ground beetles, check out this episode of Boise Biophilia.

Further Reading: