Poor Man's Weather-glass

The other day while walking our trails, I saw one of my favorite little weeds (have I already called a plant one of my favorite weeds on this blog?). Scarlet Pimpernel (Anagallis arvensis) is in the Primrose Family (Primulaceae) and has been introduced to most states and provinces in North America from Eurasia. I have never seen this plant act aggressively.

The genus name Anagallis comes from the Greek words for "to delight in again," which is a reference to the plant closing its flowers as inclement weather approaches and opening them again once clouds have passed. This is also where the common names Poor Man's Weather-glass and Poor Man's Barometer originate. There is apparently a blue-flowered subspecies (Anagallis arvensis ssp. foemina) that is common in some parts of the geographical range, but I have never seen it. Scarlet Pimpernel can be found along roadsides, in gardens, in waste areas, and in pastures.