- Author: Guy B Kyser
Puncturevine (Tribulus terrestris) kept a low profile during the drought years but seems to have exploded following this year's rains. (It is still ‘lying low', so to speak, but there is a lot more of it.)
Also known as goatheads or caltrop, puncturevine is a prostrate annual that produces large, hard, spiked seeds. The seeds disseminate by sticking to animals, tires, and feet, and can easily puncture bike and ATV tires. I tried to do a puncturevine study once but couldn't get the seeds to germinate; my theory now is that the seeds have to be run over by a vehicle before they'll sprout. Conveniently, the plant is commonly found along dirt roads, on roadsides, and on the edges of ag...
- Author: Guy B Kyser
Was happy to hear a Cap Public Radio story this morning about poison hemlock (Conium maculatum). I had some thoughts on the report.
1) Poison hemlock is not native to Nevada, as the story suggested... it's a European weed (think Socrates). Maybe the writers heard "naturalized".
2) People don't normally get violently ill just from touching poison hemlock. (I wouldn't roll around in it, though, and I would wash hands after touching it.)
3) Emphasize, emphasize, emphasize the purple spots on the stem! (Hence "maculatum".) That's how you can...
- Author: Joseph DiTomaso
In 1997-1998, the big El Nino year in California, yellow starthistle (Centaurea solstitialis) (YST) infestations throughout the state were probably the largest that I have seen in my time in California. Not only were the infestations the densest, but the size of the plants often exceeded six feet tall. The reason for this is that water uptake by the roots of YST in the Sacramento Valley and surrounding foothills is highest between March and June in both shallow and deep soils. In contrast, water uptake by annual grasses is highest earlier in the season and only in shallow soils. During the El Nino year of 1997-1998, there was plenty of available soil water long after grasses had completed their life cycle and the extensive...
- Author: Joseph DiTomaso
Yellow starthistle (Centaurea solstitialis) (YST) is the most pervasive invasive and noxious weed in California. Previous work showed that YST uses substantially more water than forage annual grasses it typically displaces. Soil moisture was 20% higher in annual grass test sites compared to YST test sites. Because yellow starthistle is found (sometimes in very extensive stands) on millions of acres of California, it is possible that removal of the thistle could substantially increase groundwater recharge and subsequent surface runoff. This could greatly improve range conditions, wildlife habitat and water supply, especially in the Sacramento Valley where groundwater levels are generally still...
- Author: Guy B Kyser
The Economist reports that Hungarian biologists have trained rabbits to preferentially eat common milkweed (Asclepias syriaca), an invasive plant (and a native to North America).