Tips for garden writers from a science writer

Much as I am itching to continue the current discussion on cultivars of native plants, I’ve got to wait until next week (my seminar schedule has me hammered – doing my third one this week tomorrow).  So instead I thought I’d throw out some suggestions for those nonscientists who blog and/or write about all things planted.

First of all, I do enjoy reading blogs, articles and books by nonscientists who venture into plant and soil sciences.  But there are common errors that both interrupt the flow and – fairly or unfairly – can cause me to question the writer’s grasp of the subject matter.  Here are some of them in no particular order:

Nomenclature:

1)  Common names are not capitalized unless they contain a proper noun.  (This is a general taxonomic rule for plants – and sorry, I didn’t write the rules!)

2)  Scientific names are always italicized or underlined; the first letter of the genus is capitalized, the species name is usually not.  (Also, they’re not “Latin names” – many scientific names actually come from Greek roots.)

3)  While we’re on scientific names and in a nod to our discussion of cultivars, let’s address that one too.  When a scientific name is followed by a cultivar name, the cultivar name is either preceded by cv., or is set off in single quotes.  The cultivar name is capitalized.  So this is how the weeping blue atlas cedar would appear: Cedrus atlantica ‘Glauca Pendula’ or Cedrus atlantica cv. Glauca Pendula.

4)  Plant family names always end in -aceae, which literally means “family.”  When someone writes “the Asteraceae family” they are being redundant.  (This always reminds me of a scene from Mickey Blue Eyes, where the characters are discussing a restaurant called “The La Trattoria” – which, of course, translates to “the the restaurant.”)

Scientific information:

1)  The word “data” is a plural noun (datum is the singular form).  Therefore, “data” must take plural verbs.

2)  “Proving” that a product or practice works.  The philosophy behind the scientific method states that one can never definitively “prove” anything.  Thus, we can have results that support a hypothesis, or we can disprove it.  (Yes, marketers do this, but garden writers shouldn’t.)

Terminology:

1)  “Pesticide” is a generic word that means “pest killer”.  Herbicides kill plants, fungicides kill fungi, and so on.  Many nonscientists incorrectly think that pesticide means the same thing as insecticide.  It does not.

2)  Flowers and fruits are reproductive structures of angiosperms (the flowering plants). Conifers do not have flowers, nor do they have fruits; their seeds are born on cones.  Many scientists, as well as nonscientists, incorrectly label the cones of Ginkgo and Taxus (yew) as fruits.

I’m sure my GP colleagues can come up with some other ones, and maybe you can as well.  Comment away!

Cake and Cultivars

I was working on something entirely different, but thought better of it. I’d like to continue Bert’s (now Dr. Mister Smartypants) really intriguing discussion.

Because when I read it, I felt a pang of…guilt? Confusion?

I’d describe my usual perspective on the “native” topic as ultra-liberal, highly plant-introduction-centric. New plant? Gimme!!! (“Native” shall appear in this post surrounded by quotes throughout, as a safety measure.)

Commenter Wes perceptively noted “part of the gardening public is becoming so enamored with the concept
of natives that I think they are grasping at straws to to assuage their
belief in ecological principal. In my opinion, many want to have their
cake and eat it too.”  As a card-carrying member of the gardening public, yes, I do like using “native” plants, there is some portion of “feel good” to it, and I adore it when a hot new cultivar is also a “native”. And many breeders, propagators, growers, and garden centers would like to assist me with this.

A good example:  the “American Beauties Native Plants” program from a large propagation nursery in Pennsylvania. Some straight species, lots of cultivars, all with marketing materials to match (tags, pots, banners).
Has “Big Plant Introduction and Branding” (really, not that big or scary an entity) co-opted “native”?  Discuss.

Finally, some advice, please:  in our campus garden, we’ve nearly an acre of new plantings in a meadow style that consists of lots of cultivars and some interspecific hybrids; all of “native” plants (even the freakin’ buffalo grass is a cultivar). How in the heck should I refer to these plants, let alone the entire concept, in our educational/interpretive materials?  Any and all suggestions will be considered.

Can cultivars be considered native plants?

One of the questions that arise in discussing native plants is the question of whether ornamental cultivars (e.g., ‘October golory’ red maple) can or should be considered ‘native’.  In short, my answer is ‘No.’

Here’s my rationale on this.  First, when we think about natives we need to put political boundaries out of minds and think about ecosystems. Political boundaries – a ‘Michigan native’ or ‘an Oregon native’ – are meaningless in a biological context.  What’s important is what ecosystem the plant occurs in naturally.  In addition to taking an ecological approach to defining natives we also need to consider its seed source or geographic origin.  Why is it important to consider seed origin or ‘provenance’?  Species that occur over broad geographic areas or even across relatively small areas with diverse environments can show tremendous amounts of intra-species variation.   Sticking with red maple as an example, we know that red maples from the southern end of the range are different from the northern end of the range.   How are they different? Lots of ways; growth rate, frost hardiness, drought tolerance, date of bud break and bud set.  Provenances can even vary in insect and disease resistance.

 


Native range of red maple

If we’re dealing with an ornamental cultivar, do we know the original seed source or provenance?   Sometimes yes, sometimes no, sometimes maybe.  Think for a minute how most ornamental cultivars come to be.  Some are developed through intentional crosses in breeding programs.  The breeder may or may not know the geographic origins of the plants with which they are working.  Or they may produce interspecfic hybrids of species that would not cross in nature.  Some cultivars are identified by chance selection; an alert plantsperson finds a tree with an interesting trait (great fall color) in the woods or at an arboretum.  They collect scion wood, propagate the trees and try them out to see if they are true to type.  If the original find was in a native woodlot and the plantsperson kept some records, we may know the seed source.  If the tree was discovered in a secondary location, such as an arboretum, it may not be possible to know the origin.

 

So, if a breeder works with trees of known origin or a plantsperson develops a cultivar from a chance find in a known location AND the plants are planted back in a similar ecosystem in that geographic area, we can consider them native, right?  As Lee Corso would say, “Not so fast, my friend.”  We still need to consider that matter of propagation.  Most tree and shrub cultivars are partly or entirely clonal.  Cultivars that are produced from rooting cuttings; for example, many arborvitae, are entirely clonal.  Cultivars that are produced by grafting, like most shade trees, are clonal from the graft union up.  The absolute genetic uniformity that comes from clonal material is great for maintaining the ornamental trait of interest but does next to nothing to promote genetic diversity within the species.  From my ultra-conservative, highly forestry-centric perspective, the only way to consider a plant truly native, it needs to be propagated from seed and planted in an ecosystem in the geographic region from which it evolved.  Few, if any, cultivars can meet that test.

Mystery tongue identified

A few brave souls dared to take on Friday’s puzzle.  Here’s a more revealing photo; the "tongue" is actually the top of a pitcher plant: 

Kudos to Hap for correctly identifying the genus (Sarracenia) of this carnivorous plant.  This particular one is S. purpurea, which is distinctive in that it has dark red, open pitchers rather than hooded ones.  You can easily see the downward slanting hairs in the throat of the pitchers.  These hairs, as Diana pointed out, keep trapped insects from climbing back out of the pitcher. 

This pitcher plant is part of my nifty bog garden that we put together this year.  If any of them get big enough, I’ll have to try Hap’s unorthodox method of slug disposal.

The New Evidence Against Glyphosate

This past week Susan over at Garden Rant asked me about a paper which she had recently read which “proved” that Round-up caused birth defects.  This study was interesting because it took embryos of chickens, exposed them to glyphosate (the active ingredient in Round-up) and then looked at the problems which the embryos had.  Indeed, there were problems at concentrations of glyphosate much lower than what you’d see in normal agricultural applications.  This is similar to other studies which “prove” how toxic glyphosate is which have been conducted over the years where various types of cells have been removed from human bodies, exposed to glyphosate, and then the resulting cellular damage has been taken as an indication that this herbicide is incredibly dangerous to us.

Studies where embryos or cells removed from the human body are tested against poisons have a glaring weakness which needs to be appreciated before we go off the deep end thinking that they prove that glyphosate is killing us.  They’re conducted in a system that isn’t at all natural.  That’s not to say they have no importance, but it’s like saying that, because it’s known that an air bubble in your bloodstream will kill you, air is dangerous.  Or like saying that, because salt injected into your bloodstream is deadly, you shouldn’t eat it.  Both air and salt can be deadly if they are in your bloodstream above a certain level, but we need to be careful to look at the specific situation with which we are dealing and take that into account when we make our judgments about how toxic particular things are to us.

I can’t argue that glyphosate can be toxic to people.  This morning I did a little literature search on it and actually found cases where people had committed suicide by drinking agricultural formulation of glyphosate  – mostly in the Eastern world.  It would be a nasty way to go too – you’d need to ingest a lot of the stuff and the primary problems would be that parts of your gastrointestinal system would be corroded.  Ouch!

If you’re going to use a glyphosate herbicide use it carefully and in accordance with its label.  Don’t go splashing it around willy-nilly.  Don’t drink it.  Don’t get it on anyone.  Don’t use more than you need to.  To do any of these things is not only dangerous, it’s also stupid.  That said, I can’t find any reason to think that glyphosate is anything but what it appears to be – an effective weed killer that is on the safer end of the spectrum relative to other chemical weed killers (and here I’m including organic weed killers too – Ever been exposed to those 20% acetic acid vinegar herbicides?  I tried one this summer — Just being near it made my eyes burn.)

Off with their heads!

About a year ago I posted my thoughts about the nursery production practice of heading young trees (“whips”) to stimulate lateral branching or columnar form or whatever.  (You can find this original column here.)  A healthy discussion ensued, much of which revolved around the need for appropriate follow-up pruning to ensure the development of a stable crown structure of headed trees.

Fast forward to last month, where a column I wrote for NPM (Nursery Production and Management) magazine hit the web.  And then the fan.

I made some people very unhappy with this article.  I had a lengthy and productive conversation with one such person last week, during which we agreed on many things, including (1) trees that are headed develop multiple leaders; (2) multiple leaders, however they’re created, need to be thinned to one central leader; and (3) uncontrolled multiple leaders can create hazardous conditions.  The bottom line, from a nursery production perspective, is that headed trees require regular pruning to create and maintain natural, structurally sound crowns.

And here’s my problem:  how many homeowners are going to perform this regular pruning?  Furthermore, how many homeowners KNOW how to perform corrective pruning?  We all know that number is going to be abysmally small.  Even for those situations where competent arborists could do this regular pruning, how many communities budget for this activity?

More troubling for me as a scientist is the lack of peer-reviewed scientific papers on this practice.  Though there are numerous papers documenting the effects of pruning, I can’t find any that specifically look at the long-term effect of heading trees during nursery production. You’ve heard all of us GP’s say it before – unless you can show us the data in a published and peer-reviewed format, we can’t regard anecdotes as anything but.

The nursery industry has invested a lot of time and money in a practice that leads to problems for which no one will claim responsibility.  Production nurseries wash their hands of the issue once the trees leave their facility.  Many retail nurseries don’t perform the necessary follow up pruning while the trees are in their care (do any retail nurseries do this?  Are they aware of the problem?).  Homeowners don’t receive information or training on how or why to perform corrective pruning.

What I’d really like to see the nursery production industry focus on is consumer education.  The metamorphosis of a sapling into a maturing tree is a wondrous thing.  Rather than interfere with the process, we need to cultivate patience as well as a respect for tree physiology.