Most folks think of only nurtured green gardens and dry yellow-brown range and grasslands during the summertime here in Northern California. It may take some by surprise that there are a few native annual plants, referred to as "summer annuals", that grow and bloom in these dry conditions. These include plants with common names like dove weed, blue curls, tarweed, and others.
Here at the UC-Hopland Research & Extension Center, one of the common summer annuals is a plant called Vinegar Weed or Blue Curls (Trichostema lanceolatum). It is named that because of the strong vinegar odor that comes from the volatile oils found in the foliage. These oils also have phytotoxic affects near the plant itself ... meaning that the oils kill or injure other plants thus reducing competition.
The plant is very well adapted to the dry summer native range of California where it thrives in grassland areas with sun-baked, hard and dry, clay-type soils. The long blue stamens (the "curls"), as the Latin genus name suggests (trichos = "hair" and stema = "stamens") have very long thin stamens that curl downward as an insect alights upon the flower. As this happens, as with this honeybee, the stamens curl down onto the back of the insect and drop pollen ... which is then carried to other flowers by the insect-pollinator.
