It might look like a cute little yellow-flowered plant, but it’s really considered an invasive weed, and it’s spreading into Southern Arizona, according to the Arizona Native Plant Society (AZNPS).
You can call it by several names:
- Globe Chamomile
- Oncosiphon Piluliferum
Although it is named Globe Chamomile, you should not drink it! This is not the same as the Chamomile tea that we enjoy drinking.
Globe Chamomile has distinctive leaves that look similar to carrot leaves. The flowers are little, round and “globe” shaped. The leaves have a pungent odor, thus the nickname, Stinknet. It grows readily in full sunlight.
It was first reported Maricopa County in the 1990’s. “By 2005 it had infested the Ben Avery facility, Cave Creek United States Forest Service Ranger station and parts of the Tonto,” John Scheuring, the Conservation Committee Chairman for AZNPS explained. “By 2015 it had heavily infested lower I-17, and with the wet year 2016 there was an explosion throughout the Phoenix Metro area.”
According to Scheuring, Stinknet, originally from South Africa, was proposed to be added to the AZ Noxious Weeds list in 2007. In an example of unintended consequences, Governor Jan Brewer had imposed a moratorium on all state rule changes, so the addition did not occur. Governor Doug Ducey reinstated that moratorium in 2014. Now the Arizona Department of Agriculture is proposing new wording of a rule change to the legislature this year, and they hope to finally get it added to the list.
Stinknet is a winter annual, and is most likely to germinate, grow and disperse in wet years.
A brochure produced by AZNPS explains, “Globe Chamomile readily infests sunny, disturbed soils that are not shaded by vegetation. It readily takes root in bare areas bordering any vegetation, both residential and wild land.”
How to get rid of it?
In order to control the spread of this weed, AZNPS stresses that removal must take place before the plants go to seed Otherwise, over the course of several seasons, they will form dense stands with prolific seed production.
Most chemicals are largely ineffective. The best way to remove the plants is by digging them up and placing them in a plastic trash bag to prevent the seeds from spreading.