[MAIPC] Philly Street Trees

Nathan Hartshorne nshartshorne at gmail.com
Tue Feb 7 06:09:13 PST 2017

So with some spare time due to rain, I googled up quite a few of the
species on the list (but certainly not all).  For the most part, it was
difficult to find information since they are not as distributed or studied
as plants like Norway Maple.  Many appeared in Invasives.org or
Invasiveplantatlas, but didn't say much.  Many of the cultivars are harder
to learn about.  Acer x freemanii is a cross between Red and Silver maples,
so I am not sure what to even think about that, but it does easily grow in
a forest setting.  Some species, like Carolina Silverbell and American
Yellowwood are regionally non-native.

It is good to note that generally it seemed that species not known for
invasions were chosen.  However, the four main caveats there are:
1)  Maybe it can hybridize with natives or other introduced species
2)  Callery Pear was infertile until people imported more trees and they
could then cross.
3)  Many species do not appear invasive, such as Autumn olive until one day
suddenly, they are.
4)  Accidental introduction of pathogen that kills natives.  Hopefully this
is more unlikely today, but who knows.

Here is some information I found:
Aesculus hippocastanum

Styrax japonicas  http://www.njisst.org/files/plantidfactsheets.pdf  -
Listed as "moderate" as a threat code by the NJ Invasive Species Strike

Acer Campestre
Other sources have said this has become invasive in some areas.

Cornus Mas  http://hvp.osu.edu/pocketgardener/source/description/co_mas.html
This source does call it invasive, but I didn't see much else.  It does
produce fruit that birds would love to distribute.

Crataegus laevigata - Was listed as invasive in Canada, though I realize
this cultivar may be less fertile (or more fertile).

I will write Lori Hayes and start a conversation.  Let me know if you want
to be individually added to it.


On Fri, Feb 3, 2017 at 9:25 AM, Muth, Norris (MUTH) <MUTH at juniata.edu>

> Nathan,
> I’m glad you picked up on this. Perhaps someone on the listserve has a
> contact with Philadelphia Parks and Rec.
> My personal view is that we might want to try to move towards something of
> a white-list type of advice where MAIPC or others could work towards
> getting these lists moved more and more towards native species and
> non-invasives (dare I say, that have gone through “extreme vetting?” I
> dare). If we could get some evidence-based information on where these
> non-natives have been used and for how long, it might be reasonable to give
> them a different designation than less well studied non-natives. I see this
> approach as entirely a pragmatic one (I’d prefer that nurseries produced
> far more diversity and abundance of native species so that they would be
> easier to recommend or mandate) - but at least this approach could make
> some inroads towards these types of plantings doing less damage and it
> might be more successful than a full frontal assault that could be more
> easily ignored and would be difficult to implement at best.
> Best,
> Norris
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ~~~~~~~~~~~~~~~~~~~~~~~~~
> Norris Z. Muth, Associate Professor of Biology
> muth at juniata.edu<mailto:muth at juniata.edu>
> office: 1054 VonLiebig Center for Science
> Office Hours Spring 2017
> M&F 11-noon,  T 2-2:30, Th 1-2:30, or by appointment
> Juniata College
> 1700 Moore St.
> Huntingdon, PA 16652
> tel: 814-641-3632
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ~~~~~~~~~~~~~~~~~~~~~~~~~
> From: Nathan Hartshorne <nshartshorne at gmail.com<mailto:
> nshartshorne at gmail.com>>
> Date: Thursday, February 2, 2017 at 5:05 PM
> To: "MAIPC Listserve (maipc at lists.maipc.org<mailto:maipc at lists.maipc.org>)"
> <maipc at lists.maipc.org<mailto:maipc at lists.maipc.org>>
> Subject: [MAIPC] Philly Street Trees
> Hi all,
> My roommate was applying for an internship with them and came across the
> list of approved Philly street trees.  Recently Philly has made a push for
> more planting similar to NYC's.  Well, she knows a lot about invasives due
> to her proximity to me talking about them.  We were very disappointed to
> find a number of non-natives (regionally non-native as well).  Other than
> crabapples (which I can't tell what species they are since they are all
> cultivars), I didn't immediately recognize any as commonly naturalizing,
> but as we all know that doesn't mean much for the future, and doesn't do as
> much for the environment anyways.
> So I was wondering what we could do as an organization (aside from me
> writing a letter to them since I live here).  An impact here could make a
> huge difference given the geographical size of the city.  Perhaps any
> contacts with NYC million trees program could be useful.  Here is the list:
> http://www.phila.gov/ParksandRecreation/environment/Documents/PPR%
> 20Approved%20Street%20Tree%20List.pdf
> Nathan
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