Monday, December 22, 2014

Street Plants in Laramie in December?!

From asphalt and snow, some grass will grow.
When Lucy suggested we post about street plants four times a year, I was not optimistic for December.  We live at 7000 ft elevation in the continental interior, far from the equator.  I set out looking for an escaped juniper or pine tree, that seemed my best bet.  I didn’t find any, but in the process I learned that I hadn’t given our herbaceous plants enough credit.  Some stay green through the winter.  I wonder if they photosynthesize on sunny days, when they’re not covered with snow?

The Easter daisies (Townsendia hookeri) in my garden and out on the prairie keep their leaves through the winter.
An Easter daisy’s version of green.  Plant is six inches across.
There’s still a bit of green grass along the Laramie River bike path.
Green grass tips (look close).
The willows are dormant now, but come spring they will keep working to break up the asphalt and reclaim their habitat.

Yesterday afternoon I made a reconnaissance around the old packing sheds across from my house, thinking there might be a protected spot where a plant waif could grow.  But no, everything was dead ... except ...
... in a driveway a flash of green stopped me.  Not only were there green leaves, there were flowers too!  But the light was low, the wind was howling, and I left photo-less.

This morning was calm, not even a breeze.  About a half inch of snow had fallen overnight, so I brushed it away until I relocated the knotweed.
Prostrate knotweed, Polygonum aviculare.
Prostrate knotweed is a very common weed, quick to colonize disturbed habitat.  Several sources note that it’s adept at colonizing cracks in sidewalks and streets.
Sometimes prostrate knotweed grows upright too.
Optimistic (green) knotweed and grass.

The snow was not helpful in shooting closeups, so I collected a sprig of knotweed to take home for portraits.
It's called “knot”weed because the stem nodes are swollen (click on image above).  The Greeks called them “many knees” – hence the name of the genus:  Poly-gonum.
Short branches at base, with green and white flowers.
Swollen stem nodes, each with a leaf and flowers.
Prostrate knotweed flowers are 4-5 mm long.

For more on street plants and their fans, check out Lucy’s December street plants gathering.  And rejoice! the days are getting longer :-)


  1. This was fun! So good to hear from a gardener in your part of the country. I thought about looking for street plants, but most of them here such as Washingtonia palm are growing in the cracks in the freeways, not conducive to picture taking!

    1. ooohhh :( I would love to see some Washingtonia!

  2. It's like being a detective - and I enjoy the way you go in closer and closer. I first became aware of Polygonum aviculare agg. in September this year . . . also while looking for plants to put in a Street Plant Post! (Except here it seems to be called Knot Grass.) Like you too - I was fascinated by its lumpiness and the way it has tiny flowers tucked in where one would never notice were it not for crawling around on the pavement specially to see them!

    1. A friend suggested I collect a herbarium specimen ... with a December collection date! I should have thought of that, but now the knotweed is buried in snow and we have an arctic air mass coming our way. It will be interesting to see if the knotweed hangs in there, perhaps protected by snow