SAVING a RARE PLANT in an URBAN ENVIRONMENT by Keith Greer and Holly Cheong

Home , Monardella, Monardella linoides, Monardella odoratissima, Monardella stoneana

A-Jacks, erosion control devices in Lopez Canyon, San Diego County, used to check water flow and thus protect the habitat of the rare willowy monardella. All images used courtesy of City of San Diego, 2003. SAVING A RARE PLANT IN AN URBAN ENVIRONMENT by Keith Greer and Holly Cheong

or its size, San Diego County is gered willowy monardella (Monardella been covered by impervious surfaces Fblessed with one of highest num- linoides Gray ssp. viminea (E. Greene) such as pavement or structures. ber of endemic species in the Abrams; see sidebars) from changes in When urbanization spreads into un- nation. Considered a hotspot for en- urban hydrology. developed watersheds, the percentage dangered species (Dobson et al. 1997), Willowy monardella occurs in the of impervious land surface increases, San Diego has also undergone waves alluvial terraces and cobble bed of in- resulting in changes to hydrology that of rapid urbanization since the 1950s. termittent streams in Lopez Canyon, include increased stream discharge and While recent conservation efforts a part of the Los Peñasquitos Preserve velocity due to urban runoff, as well as have focused on protecting species located within south and central San changes in the timing of these flows. and their habitats from direct impacts Diego County. While Lopez Canyon White and Greer (2002) documented such as urban development, active is part of a city park managed for its an annual 4% increase in stream dis- land management is equally important natural and cultural resources, indirect charge since 1972 due to watershed to protect species on lands already impacts from watershed urbanization urbanization in nearby Los Peñas- preserved. have threatened the existing monar- quitos Creek. This increased discharge This paper describes efforts of the della population. Since the mid-1970s and velocity has resulted in increased City of San Diego, in conjunction with the 4.5 square mile watershed of Lopez scouring of the streambed, undercut- the nonprofit Friends of Los Peñas- Canyon has been developed into the ting the alluvial terraces in Lopez Can- quitos Canyon, to protect a popula- suburban community of Mira Mesa. yon that support willowy monardella. tion of the federal and state endan- Currently, 65% of the watershed has The loss of alluvial terraces and the

18 FREMONTIA VOLUME 33:1, JANUARY 2005 enlargement of the intermittent stream ceived grant funding from the Califor- (RWQCB) would be very time-con- channel were predicted by Karen nia Department of Fish and Game and suming for the berm design. In addi- Prestegaard (1979) in her masters the- the California Coastal Conservancy to tion, grant funding would have expired sis. Current and pre-urbanization aerial implement an erosion control project before the permitting process for photographs support Prestegaard’s pre- to protect willowy monardella in those agencies could be completed. dictions, and can be seen in Figure 1. Lopez Canyon. The first task was to Also, the berm design could have pos- Since 1995 the Friends of Peñasquitos design the project. Several alternatives sibly impacted an already eroded sewer Canyon have documented the loss of were investigated and rejected prior to line within the canyon. Instead of risk- several large patches of monardella af- settling on the final design. ing unforeseen negative impacts to the ter large storm events. Effective man- The first alternative came from two canyon, the project team decided to agement for willowy monardella in California State Parks engineers who look for another solution. Lopez Canyon requires managing the volunteered their time to survey the After consulting with staff from changes in hydrology caused by water- monardella sites in Lopez Canyon, many agencies, it was determined that shed urbanization. along with a volunteer representing a new form of erosion control, called Recognizing this problem, staff from the Friends of Los Peñasquitos Can- A-Jacks, would be the best solution for the City of San Diego and volunteers yon Preserve. They proposed a series Lopez Canyon. A-Jacks are concrete from the Friends of Peñasquitos de- of grade control structures including armor units designed to interlock into termined that there was a need for hy- drop structures, weirs, gabions, and a flexible, water-permeable chain. A- drologic structures to slow the water bank armoring. Ultimately this pro- Jacks help dissipate water velocity, velocity and reduce scour. In addition, posal was deemed infeasible because protecting channel terraces from they determined that it would also be its cost exceeded the available funds. scouring and erosion, two problems necessary to address changes in hydro- The second alternative came from experts knew they had to solve. A- logic condition in the entire watershed. the Natural Resources Conservation Jacks also collect sediment within the This resulted in a two-phase approach: Service (NRCS) of the USDA. Their water, minimizing impacts down- a long-term goal to address the hydro- engineers drafted plans for a simpler stream from deposition, a third prob- logic changes and a short-term goal of design involving cobble berms to pro- lem in the Canyon’s waterways. protecting the existing patches of wil- tect the two major monardella sites Downstream deposition of sediment lowy monardella. from erosive wintertime flows. These into Los Peñasquitos Lagoon had al- Working with a diverse citizens ad- plans were reviewed in a preliminary ready caused significant impairment visory committee, the Cities of Poway, meeting with the federal and state re- (California State Coastal Conservancy Del Mar, and San Diego began look- source agencies in 2002. The US 1985). Collection of sediment would ing at a comprehensive, long-term ap- Army Corps of Engineers (ACOE) also help stabilize the terraces, pro- proach that would create a watershed argued that the berm for the down- vide additional habitat areas for wil- management plan for the area. Those stream site would redirect a second- lowy monardella, and hide the A-Jacks involved have just started to identify ary channel flow, possibly causing a from view. areas of stream impairment and pos- detrimental change in hydrology. An engineering firm was contracted sible solutions, but what about the It became apparent that obtaining to draft a set of plans using A-Jacks to short-term? approvals from the Corps and the Re- protect the population of monardella In 2001, the City of San Diego re- gional Water Quality Control Board without significantly altering the hy-

FIGURE 1A. Lopez Canyon, San Diego ca. 1969. Aerial photograph FIGURE 1B. Lopez Canyon, San Diego ca. 2002. Aerial photo- of the canyon prior to the development of the suburban graph of the canyon after the development of the suburban community of Mira Mesa. Note the stream bed of Lopez Creek community of Mira Mesa. Note the enlargement of the stream shown as a meandering white line crossing horizontally in the bed throughout the canyon. 2003 locations of willowy monardella center of the photograph. are shown as white triangles.

VOLUME 33:1, JANUARY 2005 FREMONTIA 19 drology of the adjacent channels. Af- ter consultations and site visits with WILLOWY MONARDELLA IN SOUTHERN involved agencies, this third alterna- CALIFORNIA tive was deemed the most feasible. Project construction began on August 11, 2003. Urban Corps of San Willowy monardella (Mon- Diego was hired to conduct the instal- ardella linoides Gary ssp. lation. This non-profit organization, viminea (E. Greene) Abrams) is a which focuses on opportunities to con- state and federally endangered serve our natural resources, provides plant species that is found along job training and educational opportu- drainages within central and nities for young inner-city men and south San Diego County. It is a women ages 18 to 25. Representatives perennial from the Friends of Los Peñasquitos herb that blooms between June and August. Canyon Preserve, Erosion Control This plant species is in the mint family Technologies, and a senior ranger for Los Peñasquitos Canyon Preserve, su- (Lamiaceae) and has a pleasant spearmint aroma. pervised and assisted with the A-Jacks Habitat for willowy monardella is extremely installation. limited. This rare plant species is only found on A small Bobcat or hand tools were terraces along natural drainage courses. As de- used to create the trench for the foot- velopment has increased in San Diego County, ing of the A-Jacks. Once the trench was willowy monardella has been threatened by completed, A-Jacks were installed on floodplain development, increased urban runoff, and invasion by the site in a long, linked chain. A-Jacks weeds. Willowy monardella does not compete well with other plants weigh about 80 pounds each and had and can be choked out by weeds which invade the streamside terraces. to be fitted together exactly to ensure In addition, sparse riparian habitat can turn into thick riparian wood- proper functioning. The installation, land with increased urban runoff, further decreasing habitat areas for which took about one week, was sched- uled to take advantage of the dry sum- willowy monardella. Urban runoff can also erode the streamside mer season when Lopez Creek does terraces where willowy monardella resides, washing the plant and its not flow. Needless to say, it was a la- habitat downstream. The latter example is what has occurred within borious process and the project team, Lopez Canyon. including Urban Corps, maintained a Due to habitat degradation, this plant species is becoming in- great attitude during the hot summer. creasingly rare. Only six known locations continue to persist, with Now that the project has been com- the largest population occurring on military land. Many popula- pleted, City of San Diego staff and the tions in upper Lopez Canyon, Soledad Canyon, and other canyons Friends of Los Peñasquitos Canyon throughout San Diego have been extirpated. It is extremely impor- Preserve hope to preserve and enhance tant that all remaining popu- the natural populations of willowy lations of willowy monar- monardella in Lopez Canyon. Annual surveys, started in 2000 (City of San della be protected and man- Diego 2000), are documenting the ef- aged. Recent taxonomic fectiveness of the A-Jacks. These re- work by Andy Sanders and ports will be provided to the federal Mark Elvin supports the re- and state resource agencies and made classification of willowy available to the public. monardella to its own spe- If our program is successful, in a few cies (Monardella viminea), years additional habitat for willowy with a new species Monar- monardella will be created in Lopez della stoneana (Jennifer’s Canyon by the natural collection of monardella) being described sediment on the A-Jacks. When that from near the US-Mexican occurs, the Friends of Los Peñasquitos Canyon Preserve expect to plant ad- border (see Novon 13(4):426 ditional willowy monardella in Lopez (2003)). Canyon to boost the population. The City of San Diego staff were Willowy monardella (Monardella able to videotape the installation of the linoides ssp. viminea), from Lopez A-Jacks and interview some of the key Canyon, San Diego County. members of the project team. This video documents the work that went

20 FREMONTIA VOLUME 33:1, JANUARY 2005 A BRIEF EXPLANATION OF THE MONARDELLA LINOIDES AND M. ODORATISSIMA ALLIES IN SOUTHERN CALIFORNIA

he genus Monardella consists of approximately with running surface water for 24 to 48 hours after T50 taxa of annual and perennial herbs that a rain) that cut through cismontane marine and are found throughout western North America with alluvial terraces of central San Diego within 20 km almost all taxa occurring either partially or wholly in of the Pacific Ocean. Monardella viminea has a California. Monardella species vary mostly in their relatively sparse pubescence (especially compared vegetative characters (as opposed to floral charac- to the closely related M. linoides ssp. linoides) and is ters), notably pubescence and the size and shape of conspicuously and rather densely glandular on the their leaves and bracts. Speciation in Monardella stems and leaves. The leaves are broadly linear to seems to be driven, in part, by a combination of narrowly lanceolate with a length to width ratio of isolation and vegetative and/or physiological adap- between 7 and 10 to 1. The inflorescence bracts tation to local conditions (personal observation, M. are conspicuously longer than the calyces. Monar- Elvin and A.C. Sanders). della viminea has a strong sweet scent of the sort Many taxonomic problems exist in Monardella. typically associated with Monardella. The Monardella populations in southern California Plants in the Monardella odoratissima species are no exception. They appear to be very similar group generally have wide leaves (lance-ovate) and and it can be difficult to distinguish between the glabrous to sparsely pubescent herbage. Their taxa; however, they can be separated into natural leaves have a distinct petiole, an acute base, and a groups based on a series of shared characters. The relatively broad blade that expands quickly to the M. odoratissima and M. linoides species groups are widest point. The stems and leaves are generally among the most difficult to distinguish in the ge- either glabrous or sparsely pubescent to sparsely nus. The taxa in these groups have regularly been short-villous. Monardella odoratissima is only repre- confused in the field and herbaria, but can be recog- sented in southern California by the derivative taxa nized by small but consistent differences between M. australis and the new species, M. stoneana (which them. was recently published in Novon 13(4)). Plants in the Monardella linoides species group Monardella stoneana (Jennifer’s monardella) is a generally have narrow leaves (broadly linear) and low, compact and non-rhizomatous perennial. It herbage covered with a short dense pubescence. grows in intermittent streams that carry water for Their leaves have a winged petiole, an attenuate several weeks to months during and after the winter base, and a consistently narrowish blade that ex- rainy season. It most often grows among boulders, pands gradually to the widest point. The stems and stones, and in cracks of the bedrock of these inter- leaves have a short dense pubescence in most cases, mittent streams in rocky gorges in the mountains with mixed long and short dense hairs in a few just east of San Diego and into northern Baja Cali- populations (e.g., M. robisonii). Monardella linoides is fornia, Mexico. Monardella stoneana stems are rather represented in southern California by a number of stout compared to the other species in the genus. It taxa including several subspecies of M. linoides, M. is sparsely pubescent to almost glabrous and less robisonii, and M. viminea (a former subspecies of M. glandular than both M. odoratissima and M. viminea. linoides). Its leaves are lanceolate to lance-ovate with a length Monardella viminea (willowy monardella) is a to width ratio of between 3 and 5:1. The inflores- wispy low growing non-rhizomatous perennial with cence bracts are noticeably rather small, of more or stems that drape out from the center, which is how less the same length as the calyces. Monardella it got its common name. It grows on secondary stoneana has a strong and pungent, minty scent. alluvial benches in ephemeral washes (drainages —Mark Elvin

into this project and provides a valu- Although this project underwent a vision, this project might still be in the able guide for anyone considering a significant number of design changes, design and permitting stage. The hope similar project. The video, titled the it was ultimately successful. One of the is that this project will stop the on- “Lopez Canyon Willowy Monardella main reasons for its success is the in- slaught of urban runoff on this sensi- Protection Project,” is available from corporation of volunteers into the tive plant species and stabilize the the City of San Diego. project. Without their assistance and eroded terraces for future populations

VOLUME 33:1, JANUARY 2005 FREMONTIA 21 of willowy monardella. Although the ACKNOWLEDGMENTS REFERENCES damage to the watershed will not be undone by this project, it will reduce This project was funded through Dobson, A.P., J.P. Rodriguez, W.M. further sediment deposition down- grants from the California Department Roberts, and D.S. Wilcove. 1997. stream and minimize erosion within of Fish and Game Local Assistance Geographic distribution of endan- Lopez Canyon. Program and the Coastal Conservancy gered species in the United States. Future projects included in the Wetlands Recovery Project Small Science 275:550–553. Lopez Canyon watershed manage- Grant Program. Volunteer assistance California State Coastal Conservancy. ment plan can build off of this effort was also provided by the Friends of Los 1985. The Los Peñasquitos Lagoon to improve the quality of this canyon Peñasquitos Canyon Preserve, NRCS, and its habitats. and California State Parks. Enhancement Plan. 90 pp. City of San Diego. 2000. Summary of monitoring results for Monardella linoides ssp. viminea. 8 pp. Prestegaard, K.A. 1979. Stream and lagoon channels of Los Peñasquitos watershed, California with an evaluation of possible effects of proposed urbanization. Masters Thesis, University of California. Berkeley CA. White, M.D., and K.A. Greer. 2002. The effects of watershed urbanization on stream hydrologic characteristics and riparian vegetation of Los Peñasquitos Creek. Conservation Biology Insti- tute Report. Available at www. consbio.org/cbi/pdf/san_diego/ penasquitos.pdf.

Keith Greer and Holly Cheong, City of San Diego, 202 C Street MS 5A, San Diego, CA 92101. [email protected]; [email protected]

Clockwise from top: Completed installation of the erosion control devices. • The A-Jacks should trap sediment, as well as protect the alluvial terraces, allowing the devices to be partially buried from view in the future. • A-Jacks erosion control device. • Urban Corps of San Diego installing A-Jacks around the alluvial terraces supporting willowy monardella.

22 FREMONTIA VOLUME 33:1, JANUARY 2005