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Saving a Mehrten Meadow

By Karen Callahan

Hell's Half Acre is a botanical heaven in the Sierra Nevada foothills where acres of brilliant wildflowers bloom in spring. Surrounded by trees and shrubs, HHA is a distinctive open habitat sometimes called a "Mehrten meadow". The forest opening is formed by shallow soils underlain by a hard volcanic mudflow, or lahar. Geologists call this a Mehrten Formation. Due to the cement-like layer and gentle slopes, rainfall collects in shallow depressions before slowly draining off or evaporating. Showy, mostly native, annual plants thrive with little competition from invasive species.

In the spring of 1997 the re-zoning and impending development of the 360 acre Kenny Ranch was announced. About 50 acres of the Ranch has been known as "Hell's Half Acre" from its use as a hobo camp, illegal dump, and, possibly, from its rocky, desert-like landscape. Kenny Ranch, on the western edge of the town of Grass Valley, is prime open land planned for commercial and residential development. In reaction to the news about the future of Kenny Ranch, CNPS members and concerned neighbors formed "Friends of Hell's Half Acre" to save this unusual natural area from destruction.

Friends of HHA began meeting with the Kenny Ranch's owners. A wildflower tour of HHA was videotaped for the local cable TV station, and reporters wrote favorable stories for the Grass Valley newspaper. With the enthusiastic leadership of Carolyn Chainey-Davis slide shows were assembled, members researched the Ranch's history, and detailed maps were drawn. Since 1997 Carolyn and other Redbud Chapter members have lead several field trips every spring. These popular field trips have been key to building public interest in HHA's future. The Nevada County Land Trust has provided expertise and support during the long negotiations involving county government and Kenny Ranch's new owners. The future of this Mehrten meadow is still uncertain. Redbud Chapter and other friends of Hell's Half Acre envision a botanical preserve, accessible to wildflower lovers of all ages and abilities.

Gray Pines (Pinus sabiniana) against the clouds of a winter rainstorm.

View of Hell’s Half Acre, elevation 2600’feet, with Limnanthes alba, White Meadowfoam, in the foreground.

White-leaf Manzanita, (Arctostaphylos viscida)

Experts visit HHA to examine the area’s geology, plants, and animals. Botanists Gordon True and Lillian Mott compiled a plant list in the 1970’s. Their list (with additions) is available on Redbud Chapter web page. Lillian’s field trips introduced many people to Hell’s Half Acre.

Several plants typically associated with vernal pools grow at HHA including Orcutt's Quillwort (Isoetes orcuttii), Dwarf Woolly Marbles (Psilocarphus brevissimus var. brevissimus), and the tiny Pansy Monkeyflower (Mimulus angustatus) pictured here.

Lichen-encrusted boulders with Sky Lupine (Lupinus nanus) and Ramm's Madia (Madia rammii).

A field trip in early May, usually the peak of wildflower season. Check our web site for field trip information. HHA is private property and trips are held with the owner's permission.

HHA is home to the largest population in Nevada County of Sanborn's Onion (Allium sanbornii var. sanbornii), a CNPS list 4 species. Several local populations of the uncommon Sanborn's Onion have been recently lost to development.

Pratten's Buckwheat (Eriogonum prattenianum var. prattenianum) was originally collected by Henry Pratten in 1851 in Nevada County.

At least 4 species of Clarkia are found at HHA, including Clarkia williamsonii.

A June sunrise view of Hartweg's Sidalcea (Sidalcea hartwegii) and Paper Onion (Allium amplectens).

Flowers of Creeping Sage (Salvia sonomensis).

Foothills Penstemon (Penstemon heterophyllus) grows on the edges of the Mehrten meadow.

Manzanita Heart with Lichens. 

Thanks to Richard Hanes, Carolyn Chainey-Davis, and Chet Blackburn for their generous assistance. 

About the Photographer

Karen Callahan is a professional photographer with a special interest in the native plants and landscapes of the Northern Sierra Nevada region. Look for her photographs in the newly published "Wildflowers of Nevada and Placer Counties, California" published in 2007 by Redbud Chapter of CNPS. Contact Karen by email at penstemonnccn.net. Photographs copyright by Karen Callahan and all rights reserved.

Photos and text © 1999 Karen Callahan. All rights reserved.

 

 

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