American Weeds in Japan

 

I visited Japan earlier this month and was surprised to spot several of our native plants behaving badly in unmanaged spaces such as along railroad tracks and on the edges of fields. The first one I noticed was mare’s tail (Erigeron canadensis syn. Conyza canadensis), an annual plant that was growing in cracks and untended sidewalk plots near our hotel in Tokyo. It was amusing to see this little weed work its way into the urban environment.

Solidago altissima

Erigeron canadensis

A trip to Mt. Fuji took us by train through rural areas and revealed a far more serious invasive: tall goldenrod (Solidago altissima). The spread of this plant in large groups and across large areas was disturbing (no pun intended). This website explains that it was intentionally brought in as an ornamental and for honeybee support around 1900 and tends to be its most aggressive in untended areas.

Aggressive spread of goldenrod

Other invasive American plants can be found on this list, including giant and common ragweed (Ambrosia), broomsedge (Andropogon), tickseed (Bidens), black locust (Robinia pseudoacacia), pokeweed (Phytolacca americana), and ticktrefoil (Desmodium). I personally saw all these things just in our short visit and limited travels.

Giant ragweed

Pokeweed

I saw other American natives being used deliberately as ornamentals such as black-eyed Susans (Rudbeckia) and scarlet hibiscus (Hibiscus coccineus). A visit to an ornamental garden in the Mt Fuji area found plants like sourwood (Oxydendrum arboreum), oakleaf hydrangea (Hydrangea quercifolia), and muhly grass (Muhlenbergia capillaris).

Other exotic plants that are invasive for us were also invasive for them, of course, but I was also particularly on the lookout for some of their native plants that are invasive to us—kudzu and Japanese knotweed, for example—and I did see them growing rampantly in untended areas, especially along railways. I also was curious about finding their native Jorō spiders and we did, particularly in the more natural areas around Mt Fuji. The webs were big and communal, just like here.

Cryptomeria japonica at
Kitaguchi Hongu Fuji Sengen Shrine 

My trip would not have been complete without admiring some of their beautiful Japanese maples both in gardens and in the wild. 

We also found lots of Japanese cedar (Cryptomeria japonica), both in the wild and at temples and shrines (these enormous trees are sometimes called Japanese Temple Cedars and are quite revered). Azaleas were not blooming but they were frequently used as urban street shrubs, and of course Japanese cherry trees were everywhere (again, not blooming).

October 2024 Moment in Nature

While autumn temperatures may go up and down, confusing humans as to whether it's "fall fall" or just "false fall," the plants know what to do. Late season native fruits are ripening and one that I always look out for is our native persimmon (Diospyros virginiana). 

I found this one on a tree near my neighborhood, same as every year, and the comfort of natural rhythms is very soothing in an ever-changing world.

While this particular discovery is my #momentinnature for this month, I will share with you a previous instance, full of the mischief of the upcoming holiday.

Strange Fruit: Oak Galls

Native oaks (Quercus spp.) are keystone species for insects and the ecosystems in Georgia. Over 550 species of Lepidoptera (butterflies and moths) use them as a host plant, and their larvae (caterpillars) are important sources of food for birds and other predators. Other insects rely on oaks too and sometimes their use of oaks creates growths that might appear to be flowers or fruit. These growths are the plants’ response to the egg-laying activities of small wasps or midges. According to this article, there are around 800 different types of galls to be found on oaks in the US/Mexico/Canada areas.

I have seen a number of different types of oak galls in my area and I have pictures of some but not all of them. I will supplement this post with photos from others (each image is credited unless it is mine). Perhaps the most noticeable of the oak galls in my area is the Wool Sower Gall. When it is at its best, it is a fluffy white ball with red spots created at leaf buds. Identification groups get dozens of requests to identify “this tree” when the galls are prolific.

Wool Sower Gall on white oak (Quercus alba)

Some galls are leaf galls – meaning the tiny insects lay eggs in the leaf – while others are stem galls. A friend of mine recently found an excellent example of a mid-rib type of gall, perhaps the Clustered Midrib Gall Wasp (Andricus dimorphus).

Mid-rib leaf gall (D. Lane photo)

Another fairly noticeable type is the Oak Apple Gall. By the time most people find it on the ground where it fell, it is a lightweight, papery husk.

Oak Apple Gall (Joe Boggs photo)

One year there was an abundance small, hard red galls that look like aborted fruits. The identification groups in Georgia got numerous questions on what tree produced these.

Small galls that look like fruits (wasp larva in center)

In researching for this article, I found great information on an Ohio website. It contains a number of articles on the different types of oak galls. It is one of the few sites that presents information without trying to give guidance on how to kill them. 

Most galls seem harmless to the tree, but some can cause minor twig damage. None are fatal to the host plant. The diversity of shapes and sizing is incredible. Look out for galls on your oak trees and be amazed at what nature can do.

A Collection of October Posts

 

This blog is seasonal. Every week the topic has something to do with what’s happening: in the yard, in the season, even what’s happening with me. For those of you who haven’t been following since day 1 (Mapleleaf viburnum: October 14, 2010), you can still enjoy the posts by scrolling through the archives on the right side of the blog.

I find it entertaining to occasionally go back and see what I posted about in the same season, even in the same month. October can be such a good month for being outdoors, enjoying an abundance of fall flowers, and delighting in the beginning of the fall color season. Here are a few of my favorite October posts over the last few years.

October is a great time to fall in love with our native asters. I have posted about them several times over the years, highlighting the different species in my area (with more in this post too) as well as tried to demystify the species of small white ones. Not only are asters number two on the list of keystone perennials, but they also are huge sources of late season nectar and pollen for native bees and butterflies. Add more to your garden!

New England aster

It’s a good time to evaluate or appreciate what you have in the home garden. Is your garden supporting the fall migration of butterflies like the Monarch? This post highlights some fall nectar plants (spoiler alert, it mentions asters as well as other plants). This earlier post is similar but you might find it inspiring.

Monarch on Blue mistflower

Other posts that seek to inspire you include this one with the Lorax to remind us that we have the power to make change in a positive direction. This next one specifically talks about including host plants for our native butterflies. It has a printable chart. This third post is your reminder to be diverse in the garden, not just for host plants but for nectar too.

If you’re just done with flowers and want to bask in the glow of the trees, here are two posts for you. One is about planting native trees that give you double duty or the more recent “Get a Tree That Does More.” Dreaming about driving up to the mountains for leaf-watching? Bring It Home: Fall Color gives you ideas for having good fall color in your own yard.