Redstem Filaree (Erodium cicutarium) is a winter annual or biennual here in Northern Colorado. The weed got its’ name from the red stems on the plant which makes it easily identifiable. The stems are hairy and plants grow in a rosette pattern. Some of the information I read said this weed germinates in early spring. Interestingly, the above pictures were taken in October after a snow. You can see there were mature plants and newly germinated seeds. Redstem Filaree spreads by seed so controlling seed production is key. It is extremely drought tolerant and once established is extremely hard to eradicate and is considered a noxious weed in Colorado.
Some interesting facts – before it flowers it does have some medicinal properties one of which is listed is as an antidote to strychnine. Redstem Filaree is also in the Geranium family. Other names for this plant are – Common Stork’s Bill, Stork’s Bill and Pinweed.
For information from CSU here is a fact sheet.