Puccinellia howellii

Puccinellia howellii is a rare species of grass known by the common name Howell's alkaligrass.[1] It is endemic to Shasta County, California, where it is known from a single population in Whiskeytown National Recreation Area near Whiskeytown. Its entire population is contained in a 1-acre (4,000 m2) complex of three saline mineral springs directly next to Highway 299.[2] The grass was first described to science in 1990[3] and no other populations were discovered despite extensive searches of the area.[4]

Puccinellia howellii

Critically Imperiled  (NatureServe)
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Poales
Family: Poaceae
Subfamily: Pooideae
Genus: Puccinellia
Species:
P. howellii
Binomial name
Puccinellia howellii
J.I.Davis

The hillsides surrounding the salt springs where the rare grass grows burned in the 2018 Carr Fire. However the bare, wet gravel slopes of the springs were largely unburned and the Puccinellia population persists.

Description

Puccinellia howellii is perennial bunchgrass, and grows in clumpy monotypic stands of stems up to 60 centimeters tall. The inflorescence is an array of branches a few centimeters long, the lower ones reflexed as the fruit matures. The grass reproduces only by seed, and seed is not produced until the individual is two years old or more.[4] The plants are mostly dormant during warm months when the soil salinity is highest, and the seed germinates during wet seasons when water flow dilutes the salt.[4]

The single population of the grass is made up of several thousand individuals, a dominant species of the vegetation in this tiny network of mineral springs.[4][5] It grows alongside other halophytes such as saltgrass (Distichlis spicata) and seaside arrowgrass (Triglochin maritima).[2]

Endangered status

Threats to this already extremely rare grass include polluted surface runoff from the highway which is just steps away from its habitat,[6] alterations in the specific moisture, pH, and salinity requirements of the plant season by season,[2] and changes in the sediment amounts entering the habitat by water flow.[2] In this habitat, freshwater is considered a pollutant, because it reduces the salinity too much for the grass to survive; management plans highlight the importance of diverting freshwater away from the springs.[2]

Other threats include grazing by black-tailed deer (Odocoileus hemionus columbianus), garbage from the road, and random events that could affect the entire population.[4]

References
  1. USDA, NRCS (n.d.). "Puccinellia howellii". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 15 October 2015.
  2. Cooper, D. J. and E. C. Wolf. (2007). A restoration and monitoring plan for Puccinellia howellii, Whiskeytown National Recreation Area, California. Archived 2011-07-15 at the Wayback Machine Colorado State University.
  3. Davis, J. I. (1990). Puccinellia howellii (Poaceae), a new species from California. Madroño. 37:1 55-58.
  4. Center for Plant Conservation Archived 2010-10-29 at the Wayback Machine
  5. Grass Manual Treatment Archived 2011-06-11 at the Wayback Machine
  6. California Native Plant Society Rare Plant Profile
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