page_title: Vernal pool
section_title: Flora
hierarchical_section_title: Vernal pool / Flora
context_page_description: Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. They are considered to be a distinctive type of wetland usually devoid of fish, and thus allow the safe development of natal amphibian and insect species unable to withstand competition or predation by fish. Certain tropical fish lineages have however adapted to this habitat specifically.
  Vernal pools are a type of wetland. They can be surrounded by many communities/species including deciduous forest, grassland, lodgepole pine forest, blue oak woodland, sagebrush steppe, succulent coastal scrub and prairie. These pools are characteristic of Mediterranean climates, but occur in many other ecosystems.
context_section_description: In vernal pools, flowering occurs simultaneously because of the seasonality of favorable conditions. Vernal pool ecosystems may include both cosmopolitan species and endemic species adapted to unique environmental conditions. These conditions include moisture gradients, salinity gradients, and reduced levels of competition. Mircrotopographical gradients also contribute to species distribution in vernal pool communities, where plants that flower sooner in the season are more likely to be found at slightly higher elevations than later flowering species. Many vernal pool plants have buried seeds which accumulate in the soil. Different species are suited to different moisture levels, and as water evaporates from the edges of a pool, distinctive zonation of species can be seen. Most pools receive annual deposition of tree leaves, which are critical to maintaining local life due to leaf detritus.
  Many upland perennial plants are unable to withstand the period of flooding. Many wetland plants are unable to withstand the period of desiccation. Therefore, venal pools are a distinctive habitat that provides a refuge from both terrestrial and fully aquatic plants. When dissolved carbon dioxide is depleted by daytime photosynthesis, vernal pool species like Howell's quillwort (Isoetes howellii) and pygmyweed (Crassula aquatica) collect carbon dioxide nocturnally using Crassulacean acid metabolism. Vernal pool basin habitats favor annual plants with some uniquely adapted perennials which suffer extensive mortality resembling annual reproduction. Annuals comprise approximately 80 percent of vernal pool flora. Listed below are some genera of the approximately one hundred vascular plant species associated with California vernal pool habitats. A typical pool will include only 15 to 25 species.
  Cosmopolitan aquatic flora
  quillworts (perennial)
  water clover (perennial)
  pillworts (perennial)
  water starworts
  succulents
  waterworts
  mousetail
  buttercups
  spikerushes (perennial)
  lilaea
  Vernal pool specialists
  stickyseeds
  calicoflowers
  button parsleys (perennial)
  snorkelwort
  false Venus' looking glass
  pincushion plants
  popcornflowers
  woollyheads
  Colusa grass
  Orcutt grass
  Solano grass
  Upland plants commonly found at vernal pools in California include yellow pansies, several sweet-scented clovers, yellow and bright lavender monkeyflowers, star lilies, and yarrow.
  Vernal pools are often threatened by development in the same way that other wetlands are. As a result, most pools have been converted into residential zones, roads, and industrial parks. That is why most extant pools occur on protected or private land such as national parks, and ranches.
  A large number of rare, endangered species, and endemic species occur in vernal pool areas. For example, the San Diego mesa mint, a highly endangered plant, is found exclusively in vernal pools in the San Diego area. Another example is the wildflower Lasthenia conjugens, which is found in limited parts of the San Francisco Bay Area. A third example is the herb Limnanthes vinculans endemic to Sonoma County, California.
caption: Vernal pool flowers, with different species occurring in zones related to soil moisture and temperature gradients formed as the pool dries out. Sacramento National Wildlife Refuge, Calif.
exif: {}