Woodrushes: A Different Kind of Rush

 

Luzula acuminata, single flowers

When I first keyed out a streamside woodrush in my yard some years ago, I was surprised to realize how different it was in appearance to the rushes I’ve seen in wet areas or even in standing water. Woodrush (Luzula spp.) looks more grass-like than those aquatic rushes (Juncus spp.) and the flowers are arranged differently.

Recently I shared a photo of a pretty woodrush with a friend. After our discussion about it, I realized that I might actually have several different species because some grow in different areas and are noticeably taller than others.

In an earlier blog that I did about sedges (Carex spp.), I mentioned the rhyme for grasses, sedges, and rushes. Apparently these still follow the “rushes are round” when it comes to the stem and don't have the nodes/joints that distinguish true grasses.

The plants are flowering now and I have them in 3 places: they are abundant in the front lawn near the street; there is a single plant in the woods behind the house; and the largest area of woods is well-populated with a small form that loves to grow in moss.

Using a number of identification keys, photos on the internet, and herbarium records for my county, I have tried my best to figure out if these are 3 different species or two. There are 4 different species reported for my county.  

Solitary seeds forming on L. acuminata

Streamside Luzula (multiple flowers)

Since one plant has single flowers, it was easy to key that one out to hairy woodrush (Luzula acuminata) because it is the only species that does. Given my location, it is likely L. acuminata ssp. carolinae. That was the lone plant behind the house. From there, the remaining plants have multiple flowers and the identification points were a bit more subjective (is the inflorescence divergent, even widely spreading, or simply erect)?  

Clearly the last two have different growing habits and even the flowers seem slightly different when viewed with a hand lens. I take little pleasure in knowing that others have struggled to distinguish common woodrush (L. multiflora) from hedgehog woodrush (L. echinata) and sometimes they have been lumped together. In the end I have decided that the ones in the lawn are species L. echinata because of the more spreading inflorescence. The one in the woods, which is smaller in stature than the others, is still a mystery. Perhaps when the seeds develop, I’ll have another clue to consider.

Multiple flowers, L. echinata

Spreading inflorescence, L. echinata