For the ravens that fly low over the Huckleberry parking lot, recent weekends of overflow cars but no picnic crumbs must have presented a puzzle. I visited this botanic preserve on Father’s Day and found cars parked out for yards on Skyline Blvd. even though the picnic area was closed by COVID-19 precautions. I also discovered ocean spray (Holodiscus discolor) blossoming cream florets over the parked cars and orange monkeyflowers (Diplacus aurantiacus) sprawling in the shade.
If you want to discover which native plants still grow in the Oakland hills with minimal pressure from exotic species, then there are few better places to start than in Huckleberry Botanic Regional Preserve. The Huckleberry Interpretive Loop Trail follows a relatively flat, narrow path from the Skyline entrance, then turns left and descends into a botanically rich canyon before heading uphill to complete the loop. Visitors can take a self-guided tour brochure at the trailhead and match plants listed with trail signs.
Instead of rehashing the brochure’s information, let me report on the trail plants beyond the brochure descriptions. To begin with, although this park’s location connects Reinhardt Redwood Regional Park and Sibley Volcanic Regional Preserve, Huckleberry has plant populations that are rare or absent in the neighboring parks. Within Huckleberry, outliers from coastal plant communities as well as some from more interior habitats meet in a mixture unique to this location. On the loop trail, chinquapins (Chrysolepis chrysophylla) and canyon live oaks (Quercus chrysolepis) mingle with Douglas iris (Iris douglasiana) and western leatherwood (Dirca occidentalis), an uncommon mixing. Huckleberry’s rocky soil and location in a summer fog corridor support its unique plant community.
Brittleleaf and pallid manzanitas (Arctostaphylos crustacea and A. pallida) grow in this park, a truly rare combination in the East Bay. The East Bay Regional Park District is revising its management plan for Huckleberry to better protect the pallid manzanitas, which grow only in several East Bay locations and nowhere else in the world. As you start on the upper portion of the loop trail, please note the sign asking visitors not to cut or remove manzanita branches. Last year, visitors cut off several pallid manzanita branches where they leaned over the trail.
One of the greatest threats to pallid manzanitas at Huckleberry is Phytophthora cinnamomi, a plant pathogen in the same genus as the organism that causes sudden oak death. This soil-borne pathogen causes root and crown rot in the pallid manzanita and many other woody species, which die within months after they first show signs of infection. Our CNPS East Bay restoration crew uses rubbing alcohol and brushes to clean shoes and tools before leaving the park. Phytophthora spores travel in soil, and these spores can then reproduce in new locations and inflict more damage. By cleaning your shoes after hiking at Huckleberry, you may also be saving plants wherever you next walk.
Along the upper portion of the loop trail are two “manzanita barrens” with populations of manzanitas growing in their exposed, rocky soil. At least some of the manzanita barrens at Huckleberry grew out of areas graded for development just before the East Bay Regional Park District acquired this land for a botanic preserve. Pioneer plants, like manzanitas, start growth in full sun, but oaks, bay trees, and shade-tolerant plants arise in the shady spots in the barrens. After some years, they will overtop and shade out the manzanitas. Where the trail turns downhill past the last manzanita sign (#15), shade from oaks and bays will let you know right away that you’ve left the summer sun behind in the manzanita barrens.
As the plant succession signs hint, plants sometimes migrate their growth away from identifying signs to sunnier areas nearby. It is not lack of observation that may be keeping you from finding a plant next to its sign. Cell phones usually work in Huckleberry, so I recommend looking at the illustrated plant list for the park in Calflora’s “Great Places” feature. Not only can you compare photos of the plant that you see, you can also learn some species not described in the brochure. For example, after you look at the signs for ferns on the lower half of the loop (#17-19), you might also use the plant list on Calflora to look for unmarked ferns in the park, such as goldback (Pentagramma triangularis), polypody (Polypodium species), and bracken (Pteridium aquilinum var. pubescens) ferns. If your interest extends to bryophytes (non-vascular plants), you can check out mosses and liverworts on iNaturalist’s illustrated Huckleberry Botanic Preserve Monitoring page.
As you climb the last portion of the loop trail, you can see the exotic/native margin below the stand of blue gum eucalyptus (Eucalyptus globulus) north of the parking lot. Our chapter’s restoration crew cleared out much of the French broom (Genista monspessulana), poison hemlock (Conium maculatum), and greater periwinkle (Vinca major) that spilled down from the parking lot. Native hoary nettles (Urtica dioica ssp. holosericea), bracken ferns, and poison oak (Toxicodendron diversilobum) have been filling the cleared areas. However, this slope will present other growth in coming seasons as plant succession keeps changing the picture.
If you go: The parking lot and main entrance to Huckleberry Botanic Regional Preserve are located on Skyline Blvd. just south of Elverton Drive in the Oakland hills. Find more information, including a wildflower list, on the East Bay Regional Park District’s page for Huckleberry. Explore more about the plants of Huckleberry on Calflora.
— Janet Gawthrop, CNPS East Bay Field Trips Chair