After spending much of last year familiarizing ourselves with many of the native plants on the property, this year we’ve resolved to try harder when it comes to positively identifying our native grasses.

Western Sweetgrass (Hierochloe occidentalis)

Identification of native grass species, quite simply, can be very confusing.  For much of the year their appearance can be relatively non-descript, especially to novices such as ourselves.  Last year, once a number of our grasses on the property had set their seeds and awns, I made an effort to identify as many as I could, but the vast majority turned out to be undesirable non-native species.

Despite the recent unsettled weather, and there’s much more on the way, a quick walk on the property turned up one native grass that is difficult to miss.  Western Sweetgrass (Hierochloe occidentalis).

This morning, between rain showers, I braved a quick walk on the property, and got caught out in this...hail!

The genus name, Hierochloe, is derived from the Greek Hieros, meaning sacred, and Chloë, meaning shoot or blade.

Western Sweetgrass is also known as California Sweetgrass, or California Vanilla Grass, and is native to the west coast of North America, from California to Washington.  This is an evergreen perennial clumping grass, with broad green blades that grow greater than a foot tall, and spreads via creeping rhizomes.

Clumps of Western Sweetgrass can appear very lush at this time of year, where there's little competition from other plants

The area where I photographed these specimens is being heavily encroached upon by the non-native Myosotis latifolia.  It seems, at least to my eye, that where the Myosotis is most prevalent, the Sweetgrass is sparse if present at all.  I’ll be curious to see if when these Forget-me-nots are removed, if the Sweetgrass is able to fill in those areas

This less robust clump of Western Sweetgrass is almost completely surrounded by Myosotis latifolia

This species isn’t particularly distinctive for much of the year.  By late winter though its flowering culms push at least 8 inches above the grassy blades, making it much easier to distinguish.

In mid-late winter the flowering stems begin to form

At this stage it wasn't obvious which grass species this would prove to be

Just before it blooms the wavy stalks are distinctive enough to help identify this species.

Western Sweetgrass

As the buds mature, the wavy stems become more evident

Western Sweetgrass

Until at last the buds begin to open...

Once in bloom the florets are impossible to miss.

...revealing their pipecleaner-like stamens

The structure of the grass in bloom made identifying it much easier

The blades of this grass are sweetly scented when dried or crushed, hence its common name, but you’ll have to take my word for that as scratch-and-sniff blogs have yet to be invented.  The sweet aroma of this grass is reminiscent of freshly mown hay, which is attributed to the presence of coumarin.

How can a grass be deer-resistant?

Hierochloe occidentalis is highly deer resistant, in fact, here it’s completely untouched.  The production of coumarin, which is a very bitter tasting phenylpropanoid, helps to defend this grass against predation.  This helps to explain why Hierochloe occidentalis is so deer resistant, it simply doesn’t taste good.  So it seems ‘Sweetgrass’ isn’t so sweet after all!

Coumarin in Sweetgrass is a precursor to dicoumarol, a naturally occurring anticoagulant.  Coumarin can be transformed into the anticoagulant dicoumarol, a Vitamin K antagonist, by a number of species of fungi.  Dicoumarol is the compound responsible for ‘bleeding disease’ in livestock that are fed moldy Sweet Clover hay.

Western Sweetgrass contains the bitter tasting compound, coumarin

California Sweetgrass is most at home in coniferous forests, and grows very well in shade.  These specimens are down toward the valley floor tucked under some redwoods, Douglas fir and bigleaf maples, and its preference for damp soils is evident as it becomes more abundant toward the creeks.  We don’t see it at all on the exposed dry orchard slope that receives much more sun, although we do have another bunch grass there that we suspect is native, but is as yet unidentified.

It is important to note that Hierochloe occidentalis, outside of its native range, easily escapes cultivation, and can become highly invasive.

Unfortunately, these specimens of Western Sweetgrass are growing robustly in an area where we were considering keeping a few diary goats in the not too distant future.  It would be a shame to lose such a large collection of this native grass, so we may need to relocate some of this grass out of our future goat’s reach.

Hierochloe occidentalis

Surprisingly, we’ve also discovered a very large collection of Calochortus leaves growing in the same area this winter, presumably Calochortus albus which was found growing elsewhere on the property last spring.  The Calochortus won’t bloom until late April, but we have no intention of leaving those for the goats either.  Rather than move the Calochortus and the sweetgrass, I’m now wondering if it might be easier to consider relocating our future goats instead!

Hierochloe occidentalis

In the meantime we seem to have at least three other species of unidentified clumping grasses at various locations throughout the property that I’m determined to identify. It’s time to hit the books and see if this spring we can finally figure out who’s who!