This description comes from the 2nd edition Jepson Manual: Vascular Plants of California. Diplacus douglasii is a diminutive annual herb that produces a magenta flower. The overall stature of the plant is very small, varying in height from 0.3 – 4 centimeters tall. Like other monkeyflowers, the flowers are bisexual and bilaterally symmetrical, with fused petals that form a tube-throat. The throat has gold and purple stripes, which form bold mottling. The tube and upper lips are magenta, and the lower lobes are so reduced that they appear absent. The flowers can be open or cleistogamous, staying closed and self-pollinating. The flower is persistent and sits atop a 2 – 4 millimeter pedicel. The calyx is generally green, hairy, and ranges in size from 8 – 14 millimeters, with unequal lobes. The leaves are ovate to obovate blades, which range in size from 5 – 28 millimeters. The upper side of the leaves are a shiny green and are generally hairy. The seeds are hard, asymmetrically-ovid, and range in size from 2.5 – 6.5 millimeters.
Distribution
Diplacus douglasii occurs between 45 – 1200 meters elevation in the mountains and foothills of the Cascade and Sierra Nevada Ranges in California and Oregon. It is also found in Southwestern Oregon, Central Western California, and in the Warner Mountains of California D. douglasii is classified as a serpentine indicator and hence is most commonly found serpentine soils, but can also be found on bare clay or granitic soils. As a hydrophyte, it is generally found along the upper banks of small creeks, and is classified as a facultative wetland species. However, it is important to note that D. douglasii is equally likely to be found in wetland and non wetland habitats, also occurring in chaparral and foothill woodland communities.
Ecology
Diplacus douglasii flowers between February and April. Growing on serpentine soils, it has adaptations to survive conditions most plants can't tolerate. Serpentine soils are known to be deficient in essential nutrients for plants. In addition to being low in essential plant nutrients such as nitrogen, calcium, phosphorus, potassium and sulfur, serpentine soils also have high levels of magnesium and heavy metals including nickel, cobalt and chromium, which are toxic to most plants. Other plants commonly found growing alongside M. douglasii include: Creek clematis Bigleaf maple Yellow monkey flower Narrowleaf willow California wild rose Alkali rye California mugwort White alder California bay Red fescue California blackberry Black cottonwood California box elder Columbine
Research
Monkeyflowers "have become model systems for the study of evolutionary processes in nature", because of their diversity in life history and morphology, varied reproduction and ease to work with in experimental settings. They have currently sequenced the full genome for Erythranthe douglasii with 100bp paired-end at 40X coverage. Because of its affinity for serpentine soils, studying D. douglasii presents an opportunity to better understand adaptive traits in extreme environmental conditions. Researchers have found that distinct populations of D. douglasii appear to have different environmental response thresholds for when they begin producing more cleistogamous versus open flowers. This means that different populations have varying rates of inbreeding, resource use, and ability to survive hot and dry conditions. Understanding this mechanism could give scientists insight into how plants adapt to climatic shifts of warmer and drier conditions.
