Ainsworth Linear Arboretum tour – April 6, 2013

I found this event on the Portland Parks and Recreation Arbor Month calendar.  I’ve wanted to know more about these trees along the median of NE Ainsworth for some time, and today was a perfect introduction, thanks to the leadership of Karl Dawson of Portland Parks and Recreation and Jim Gersbach, founder & curator of the arboretum.

Apologies in advance for the lack of photos – I’ll be back to this place quite a bit I’m sure, as the season moves forward to provide leafier subjects.

The arboretum is part of Jim’s effort to diversify Portland’s urban forest, a much recognized need following increased awareness about the vulnerability of the urban forest with a majority of trees represented by only a handful of species.  Large old maple trees are aging out, and we’re losing elms to Dutch elm disease.  Introducing an alternative to the convention of boulevard tree plantings of all one species, the Ainsworth Linear Arboretum reveals the diversity of trees that can be grown in our city.  At least sixty species are already represented in this 2-mile section of street median and wide curbside planting strip. Check here for more information on the arboretum, as well as the Friends of Trees blog.

Despite pouring rain as I write this Saturday night, and all of the previous night, the morning and midday dry weather encouraged me to walk over to the tour meeting spot from my home. Today’s tour covered just a section of the arboretum from NE 6th.  I’m not exactly sure how far east we walked, but we didn’t make as far as Alberta Park, which is at the corner of NE 19th.


Here Karl shows us the palmately compound leaf of a horse chestnut tree, Aesculus hippocastanum, which is common in some of Portland’s older neighborhoods.  He explained that residents tended to plant trees that were familiar to them as they settled this area from the east. Though not native to the US, this tree is widely planted.

Bigleaf maple, Acer macrophyllum, is a native tree distinguished from other maples (I learned today) by it’s pendent inflorescence. Flowers are held upright in other species.


Saucer magnolia, Magnolia soulangiana (I think) — we talked a bit about the ancient origins of magnolias. Pollination by beetles explains the robust structure of their flowers. 


The Ginkgo biloba were just beginning to leaf out.  Ginkgo trees always make me think of my native Japan, but I was reminded today that they are native to Oregon too — if you look in the fossil record back a few million years.

IMG_3006   IMG_3011

Jim Gersbach shows us a variegated tulip tree, Liriodendron tulipifera.  I assume it’s the cultivar called ‘Aureomarginatum.’  The foliage of this tree is going to be really eye catching when it gets a bit larger.  By the way, if you want to find out more about trees, Jim is definitely the person you want to hang out with.  All I can say is wow, he knows a LOT.  And no doubt what we learned from him today is just the tip of the iceberg.



Jim points out the opposite branching on this Raywood ash, Fraxinus angustifolia ‘Raywood.’


A disease resistant elm from Asia (oops, didn’t get the name) to please the folks who want a replacement for elms that are being lost:



Dramatic colors on these upheld new leaves of a tupelo (Nyssa sp.)

If you’d like to take this tour –which I highly recommend — there’s a map for self-guiding, or wait for the next tour, offered twice a year in the fall and spring.

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6 Responses to Ainsworth Linear Arboretum tour – April 6, 2013

  1. Julie Fukuda says:

    Oh, how I envy you the opportunity! For first class requirements, Scouts have to learn to identify ten trees. I have a few choice places to walk with them, where I can teach them once and let them test themselves along the route. I like about twenty varieties with lots of repeats so would love a walk that offered so much. Even the local parks tend to cut down anything they consider “junk” trees… those hardy volunteers like mulberry or fatsia or umbrella palms (planted by birds)

  2. I am embarrassed to admit I’ve never walked more than just the stretch from 37th to about 29th…I really need to see more of this treasure, thanks for the push!

  3. Jim says:

    Julie –
    The Nyssa species in your photo is the Chinese tupelo – Nyssa sinensis. Their new foliage emerges distinctly red in color. Has the same great red fall color as the American species.

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