|Wispy inflorescence of Ventenata dubia in foreground|
In an earlier post I discussed how a group of winter annual grasses are spreading like wildfire in the vast Sagebrush ecosystem in the western part of the USA.
This armageddon is destroying not only the pristine sagebrush shrubs which are critical to numerous animals like the sage grouse, but it also is significantly lowering the forage value of the land as palatable perennial grasses are replaced by the mostly unpalatable invasives.
In addition to earlier invasives like Bromus tectorum (cheatgrass) and Taeniatherum caput-medusae (medusahead grass), a newer species has been creating problems for land managers.
|Distribution of V.dubia (EDDMaps, 2022)|
Ventenata dubia was first discovered in Washington State in the early 1950s. It is native to Southern Europe and North Africa, and it has rapidly spread at the rate of 1.2 million hectares per year (Native Invasive Plant Council, 2001), which means an area three times the size of Rhode Island is being invaded every year! It now is found in 11 states and 5 Canadian provinces, and land managers are frantically trying to slow its spread while it is still possible to do so.
|Invasion by Ventenata dubia (photo credit: Novak et al)|
Like other winter annual grasses that have caused havoc in the local ecosystem, V. dubia tends to create a so-called grass-fire cycle, where its presence increases the probability of fires, which in turn removes its competitors and allows it to overran the area. Another way that winter annuals can outcompete other plants is by germinating in fall or early winter, and senescing by mid-summer. This gives it a head start when it comes to taking advantage of the early spring moisture.
|The grass-fire cycle of T. caput-medusae|
This species has only recently arrived in Montana, and while botanizing in a local park in the city of Bozeman, I stumbled on a small cluster hidden amongst the other grasses.
On first look, the grass does not exactly inspire dread. Unlike T. caput-medusae with its alien looking inflorescence, or B. tectorum with its multitudes of sharp spear-like awns, V. dubia looks like a puny weakling that would roll over with the smallest puff of wind.
|The sharp spear-like awns on B.tectorum is more intimidating than the diffused panicles of V. dubia|
|Ventenata dubia whole plant. Notice weak shallow roots|
|Very long ligule of V. dubia and the remnant dark red color of a node|
|Dried spikelets of V. dubia with ribbed glumes and lemma with long awns.|