Setaria helvola (Yellow Bristle Grass) is a species of annualgrass in the family true grasses. They have white flowers. Individuals can grow to 3 feet.
Definition: Of plant duration, a plant whose life span ends within one year after germination, e.g. a winter annual germinating in the autumn and flowering in the spring (esp. in Mediterranean climates), approximately synonymous to therophyte, c.f. biennial, ephemeral, perennial, c.f. also of flowering with respect to architecture, hapaxanthic, monocarpic, pleonanthic.
Definition: The relative tolerance of the plant to calcareous soil. Calcareous soil is defined as soil containing sufficient free CaCO3 and other carbonates to effervesce visibly or audibly when treated with cold 0.1M HCl. These soils usually contain from 10 to almost 1000g/kg CaCO3 equivalent.
Definition: The ability of an organism to resist burning.
Comment: If a plant can carry a fire—and most can—it is scored as "not fire resistant" in the USDA PLANTS database where this characteristic is evaluated with reference to problem fires in California. http://plants.usda.gov/charinfo.html
Definition: The minimum tolerable temperature is the lowest temperature recorded in the plant’s historical range. If this is not available, the record low January temperature recorded at climate stations within the current geographical range of the plant is used. This definition does not apply to summer annuals.
Definition: Minimum tolerable rainfall (in inches), expressed as the average annual minimum precipitation that occurs 20% of the time (i.e., the probability of it being this dry in any given year is 20%) at the driest climate station within the known geographical range of the plant. geographical range of the plant. For cultivars, the geographical range is defined as the area to which the cultivar is well adapted rather than marginally adapted.
Comment: Minimum precipitation tolerance: Minimum tolerable rainfall, expressed as the average annual minimum precipitation that occurs 20% of the time (i.e., the probability of it being this dry in any given year is 20%) at the driest climate station within the known geographical range of the plant. Maximum precipitation tolerance: Maximum tolerable rainfall, expressed as the annual average precipitation of the wettest climate station within the known geographical range of the plant. For cultivars, the geographical range is defined as the area to which the cultivar is well adapted rather than marginally adapted.
