By PATRICIA SIMPSON
When I’m out in the field at this time of year, one of the plants that visitors are most curious about is Stephanomeria diegensis, commonly known as San Diego wirelettuce or San Diego wreath plant.
This usually tall and twiggy-looking native plant stands out in a Seussian way. In the spring, most people will dismiss it as just another common non-native invasive, such as prickly lettuce (Lactuca serriola) or another thistle-like relative. Young plants bear broad dented leaves that spread on the ground in a circle. But in the hot summer sun, San Diego wirelettuce starts growing up and up with a central stem that produces “twiggy” branches all the way around. Some larger plants may reach 6 to 8 feet in height.
San Diego wirelettuce acquires its full whimsical appearance when it blooms in the summer and well into the fall. The small clusters of delicate, mostly white, sometimes pinkish, flowers almost look like large snowflakes suspended in the air and since wirelettuce tends to thrive on disturbed slopes, a patch of these plants can look quite striking.
In addition to San Diego wirelettuce, Mission Trails might also be home to another Stephanomeria species: Stephanomeria exigua, commonly known as twiggy wreath plant or small wirelettuce. As the common name indicates, S. exigua is usually smaller in size, but the two species can be very difficult to tell apart. Examination of the seeds with a hand lens or macro-photographs is often necessary to tell the two apart.
In this observation of the month, Alan King took nice shots of the seeds and the iNaturalist community was able to confirm the identification of his plant as San Diego wirelettuce. Visit bit.ly/2SL0UTZ.
Because of its long-lasting blooms, San Diego wirelettuce is particularly important to pollinators that have a life cycle extending into the cooler months of fall, such as some of our native bees.
Now that you know all about San Diego wirelettuce, you’ll start noticing the plants on the side of the freeway. But please, keep your eyes on the road!
— Patricia Simpson is a trail guide at Mission Trails Regional Park.