Streptanthus callistus

{{Short description|Species of flowering plant}}

{{Speciesbox

| image = Streptanthus callistus 123519271.jpg

| status = {{TNCStatus}}

| status_system = TNC

| genus = Streptanthus

| species = callistus

| authority = J.L.Morrison

}}

Streptanthus callistus is a rare species of flowering plant in the mustard family known by the common name Mount Hamilton jewelflower.{{cite web|url=http://www.morgan-hill.ca.gov/DocumentCenter/Home/View/5105|title=Biological Evaluation, Monterey S. of Watsonville Biological Evaluation Santa Clara County, California, Live Oak Associates, Inc.}} It is endemic to Santa Clara County, California, where it is known from only about five occurrences around Mount Hamilton.[http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Streptanthus+callistus The Nature Conservancy] It grows in chaparral and woodlands and on dry scree. It is an annual herb producing a small stem up to 8 or 9 centimeters tall with a bristly base. The toothed oval leaves are under 2 centimeters long. The inflorescence is a cluster-like raceme of flowers, the top ones sterile. The fertile flowers on the lower raceme have calyces of bristly purple-green sepals under a centimeter long with flaring purple petals at the tip. The sterile flowers at the top of the raceme have narrow, elongated, hairless purple sepals. The fruit is a cylindrical, bristle-studded silique measuring up to 2 or 2.5 centimeters long.