The East Bay Regional Parks Botanic Garden in Tilden Park Revisited

Mr Roof came home from army service in Europe… and returned to work at the Tilden Botanic Garden in February 1946. Although the garden’s basic plantings had been saved, during the four war years the garden had reverted to an incredible coastal jungle. Weeds were everywhere and were head high. The grass in the meadows was three feet tall, matted and rematted, tough and hard to clear. The creek was a jungle of willows; wide thickets of poison oak had reclaimed what had been the most pleasant open stretches of the garden.

Rimo Bacigalupi, in Journal of the California Horticultural Society
January 1965

In 1965 Dr Rimo Bacigalupi described the twenty-five-year-old East Bay Regional Parks Botanic Garden in Berkeley’s Tilden Park in the Journal of the California Horticultural Society (Vol. 26, No. 1). A close friend and colleague of James B. Roof, the garden’s founding director, Dr Bacigalupi was able to recount the garden’s history from the vantage point of one who had been there through all of the critical developments of the first quarter century. He tells us how Howard McMinn, professor of botany at Mills College in Oakland, conceived of the need for a native plant botanical garden in northern California in 1938, and of the vital roles played by August Vollmer and Aurelia Reinhardt, both members of the board of directors of the East Bay Regional Park District, and, of course, by Jim Roof. He explains that the garden is positioned favorably — in the zone of transition between two vast phytogeographic areas (the North and South Coast Ranges), and also in an area of compromise between interior heat and mild coastal influences — to allow cultivation of the broadest possible variety of plants native to California, from Mexico to Oregon and from Nevada to the Pacific. Dr Bacigalupi’s descriptions of the garden — exemplified especially by its aspen­-fringed Sierran meadows — must have inspired many native plant enthusiasts to seek out this California native showplace in the Berkeley hills.

The garden recently celebrated its fiftieth anniversary, and this seems a good time to take stock of what has occurred during its second twenty-five years and to suggest the broad outlines of where we may be heading in the years to come.

Conifers and Other Trees

In 1965 the garden’s famous conifer collection was very young, resembling the fine open meadows dotted and fringed with Shasta red fir saplings near the top of Anthony Peak in Mendocino National Forest, a site Roof loved and wrote about most poetically. Today many of the conifers are quite mature, and the same can be said of the hardwoods. As the trees grew, the garden began to lose some of the open feeling of its broad, central Sierran spaces. So we have gradually, and selectively, removed surplus trees from the meadows, leaving taller groves on slopes or on the margins of the garden. The open spaces provide beckoning vistas and help to maintain a sense of depth.

Roof’s original arboreal collections have come of age in splendor. The old nutmeg (Torreya californica), from near El Portal in Yosemite, is spectacular. Our Santa Lucia firs (Abies bracteata) were like Christmas trees in the photograph Dr Bacigalupi showed in 1965; today they are outstanding groves of mature trees, many with the narrow, spire-like top characteristic of trees in the wild, and all heavily laden with sap-dripping, bristly cones in most years. Grand fir (Abies grandis), red cedar (Thuja plicata), Sitka spruce (Picea sitchensis), and western hemlock (Tsuga heterophylla) are other mature conifers that make superb displays.

Black cottonwood (Populus trichocarpa), from San Luis Obispo County, lights up a comer of the garden in fall

Black cottonwood (Populus trichocarpa), from San Luis Obispo County, lights up a comer of the garden in fall

Roof tried a number of selections of white fir (Abies concolor). After fifty years of trials, the most reliable is from a population on Mt. Piños in Ventura and Kern counties. These trees have attractive gray foliage, and they have kept their full form, with lower branches intact, longer than our Sierran trees. Roof’s collections of Pacific silver fir (Abies amabilis) and weeping spruce (Picea breweriana) from the Klamath Mountains were planted together on a cool slope, where they are full-formed and thriving, but remain the size of saplings. Infested with oak root fungus and balsam woolly aphid, two of the most dreaded afflictions that can assail a fir, the garden’s original noble firs (Abies procera) long ago lost their former beauty and were removed, but saplings are replacing them. The original grove of eight-foot-high bristlecone pines (Pinus longaeva) succumbed to borers and bark beetles that took advantage of trees weakened from growing in the most vicious potters’ clay in the garden. We now have a new batch of small bristlecones planted out in friable soil.

The delicate tracery of aspens in winter — a grove referred to by James Roof as the ballerinas

The delicate tracery of aspens in winter — a grove referred to by James Roof as the ballerinas

The real charm of the garden comes from its open vistas surrounded by rich, multi-hued, texturally varied mixtures of conifers and hardwoods. Some of the outstanding hardwood trees are ironwood (Lyonothamnus floribundus), Catalina cherry (Prunus lyonii), black cottonwood (Populus trichocarpa), black oak (Quercus kelloggii), and vine maple (Acer circinatum). Deciduous trees and shrubs provide wonder­ful fall color, and not only from their leaves. Many have intensely colored twigs that paint the garden in cheerful tones throughout the winter. The garden’s high-mountain feeling is probably most evident in winter, when the Sierran meadow is surrounded and broken up by the maroon twigs of American dogwood (Cornus stolonifera) and Mackenzie willow (Salix mackenziana), the yellow of buttonwillow (Cephalanthus occidentalis), the yellowish green of other low-statured montane willows, and the stark white trunks of aspen (Populus tremuloides). We intend to spread these influences, introducing more plants with colorful twigs and bark in parts of the garden that seem monotonously gray-green in winter.

Annuals and Perennials

The garden has proceeded through a predictable pattern of plantings. In its early years, trees and shrubs were emphasized to establish a stable framework. That accomplished, Roof was able to experiment more with annuals and perennials. His most impressive accomplishment in this regard was the creation of a realistic and floristically rich sea bluff, using mostly plants gleaned from Pt. Reyes before it became federal land. Roof often said that he never planted a poppy in the garden. Prior to the policy of suppressing fires and the elimination of grazing, both of which contributed to encroachment by coyote brush (Baccharis pilularis), the ridges of Tilden Park were sheeted with poppies. Clearing, weeding, graveling, and base rocking in the garden provided ideal habitat for poppies, which came in by themselves and spread everywhere.

Roof did bring in other wildflowers, which make extensive displays of color, for example, a large-flowered farewell-to-spring (Clarkia rubicunda) from San Bruno Mountain and Chinese houses (Collinsia heterophylla) from the east side of the Berkeley hills. When Wayne Roderick took over in 1974 as the garden’s second director, he expanded the herbaceous collections, especially the collection of bulbs. With so many herbaceous plants endangered and close to eradication in the wild, the gar­den’s emphasis on perennials will not diminish.

The west half of the garden is underlain by impenetrable gray clays of the eight-million-year-old Siesta Formation. Much of the garden, therefore, can be considered to be a helpful demonstration of plants that can be grown on local clays. More discriminating plants must be grown on raised mounds of well drained soil. Most of the garden’s mounds are made of quarry base rock, the sterile, unsorted, crushed debris from local quarries. Composition is usually not particularly important, but it is critical to use base rock that is on the looser end of the spectrum, that is, with less clay. Roof had an alpine garden, of which he was justly proud. In it he grew white mountain heather (Cassiope mertensiana) and purple mountain heather (Phyllodoce breweri), timberline columbine (Aquilegia pubescens), and other choice tundra plants. He had a theory that they needed shade to survive lowland culture, so he built his rock garden beneath a grove of Jeffrey pines. In time, irrepressible pine roots invaded and enveloped the alpine garden, choking out the perennials, and it has been impossible to reestablish them there.

In the process of trying out new sites for our high-elevation perennials, we have also experimented with new soil mixes, taking advantage of some of the horticultural advances of the last ten years. We discovered also that most of the alpines did well in full sun, especially if they had a somewhat northerly exposure, a nearby (but not too close) grove of trees to give afternoon shade and coolness, or some big rocks to shade them immediately. The most successful new soil so far has been a sharp, well aerated mix of equal parts granitic gravel, coarse granitic sand, and nitrolized fir bark. Alpines thrive in it.

Southern styrax (Styrax officinalis var. fulvescens) is among the most flowery, fragrant, and reliable of shrubs for dry California gardens

Southern styrax (Styrax officinalis var. fulvescens) is among the most flowery, fragrant, and reliable of shrubs for dry California gardens

Special Plants

The basic organization of the garden is one of ecological-geographical sections, and a number of subsections have been developed since 1965. The spectacular Antioch primrose (Oenothera deltoides howellii) and the Antioch wallflower (Erysimum capitatum angustatum), both of which are on the federal list of endangered species, are thriving in the Antioch Dunes subsection. The wallflower is so at home that it has been invading adjacent parts of the Foothill section, and there is now a sizable colony, which contributes to the security of this species on the planet.

A nearby talus slope displays many denizens of rock slides, such as Lindley’s blazing star (Mentzelia lindleyi) and giant blazing star (Mentzelia laevicaulis), that would be difficult to maintain with anything less than perfect drainage. A pond features many of California’s most attractive aquatic plants, among which water shield (Brasenia schreberi) and buckbean (Menyanthes trifoliata) are especially useful to water-garden makers. The moist beds at pond’s edge are massed with bunches of the glaucous sedge (Carex spissa) and tight green groundcovers consisting of mixtures of Pt. Reyes checker mallow (Sidalcea calycosa subsp. rhizomata), oval-leaved leatheroot (Psoralea orbicularis), and whorled marsh pennywort (Hydrocotyle verticillata).

Roof’s wild meadow, which was a sward of exotic annual grasses punctuated by mule ears (Wyethia angustifolia), is now a meadow of native bunchgrasses that were growing in the Berkeley hills aboriginally. It is especially popular with visitors, some of whom wonder why we keep an unkempt grass patch and others who are dazzled by the vibrant mix of airy, nodding, stiff, and delicate inflorescences.

The garden has come to be noted for certain collections in addition to its conifers. There is the world’s most complete collection of manzanitas (which has figured prominently in two revisions of the genus and in many technical reports), and there is perhaps the richest array of native perennial grasses in any garden in the western states.

Snow mountain buckwheat (Eriogonum nervulosum), a difficult garden subject that, in the wild, inhabits deep, sliding serpentine talus slopes

Snow mountain buckwheat (Eriogonum nervulosum), a difficult garden subject that, in the wild, inhabits deep, sliding serpentine talus slopes

Some exciting plants to look for are the delicate but dense, highly floriferous, miniature manzanita, Arctostaphylos myrtifolia, endemic to the heat-baked Eocene sandstones of Ione; a huge carpet of Sonoma sage (Salvia sonomensis) that drapes itself over a west-facing rocky bank in purple masses, blooming profusely and looking thrifty year round with no more care than the casual removal of a few stray vetches, the only weed capable of penetrating it; southern styrax (Styrax officinalis var. fulvescens), with waxy white flowers perfuming the entire east half of the garden; a collection of bearberries (Arctostaphylos uva-ursi) that fascinates and bewilders because, although hailing from nearly every known locality in California, no two seem alike; the crimson-flowered, moonscape-dwelling Snow Mountain buckwheat (Eriogonum nervulosum); the feathery, massed panicles of nodding needlegrass (Stipa cernua), which far surpasses the coarser captivations of its well known sister, purple needlegrass (Stipa pulchra); lots of azaleas; and a delightful display of mariposa lilies and other bulbs. These are some of our favorites; but the list is almost endless.

New Structures and Facilities

Some of the most conspicuous changes since 1965 have been in the garden’s structure and facilities. At that time there was no heated building in which staff and visitors could take shelter from the cold or the rain. In 1973 a small visitor center was built, with a crew office, reception room, and auditorium. In 1978 the main nursery was enlarged, and in 1985 a second greenhouse was built. These expanded propagation facilities both meet the garden’s need for nursery space and provide additional room for plant sale stock.

Basket grass (Muhlenbergia rigens), California native alternative to pampas grass, screening the garden’s Juniper Lodge

Basket grass (Muhlenbergia rigens), California native alternative to pampas grass, screening the garden’s Juniper Lodge

In 1986, with the help of the California Conservation Corps and Jeff Ingraca, a gifted park district carpenter, the rustic Juniper Lodge in the middle of the garden was rebuilt. This building, essentially a tool room and potting shed, had served at one time as a park office. Jim Roof took special care to give the building a low profile, fitting it into the glacial moraine topography of the Sierran meadows. However, after his retirement, the lodge was occupied by a zealous clan of garden volunteers, who needed and deserved more capacious accommodations for their propagating activities. There was also a problem with dry rot and a roof that was little better than a sagging tarpaulin. The new lodge was designed to give the impression of a cookhouse at a mountain forestry camp, and it fits well into the garden’s Sierran scene. It should serve the needs of garden volunteers for many years.

Into the interior rockwork of the old lodge Roof had placed brass plaques bearing the names of famous towns of the Mother Lode. By giving the garden a Gold Rush theme, he sought to make it seem all the more Californian. These plaques have been preserved in the reconstruction. Roof also used walls of native rock and flagstone steps throughout the garden, which resembled Gold Country masonry and dry rock walls.

With the expanding ecological awareness of the 1970s and 1980s, which movement Jim Roof helped to inspire, native American values were embraced, and naturalism in the landscape was increasingly emphasized. The one thing that did not seem natural and rustic in Roof’s landscape was the unrelieved regularity of the rock walls and exposed concrete. Taking inspiration from the splendid work of Philip Johnson at other Bay Area botanical gardens, we have built naturalistic rock outcrops in focal planting areas, and we are reducing the number of artificial walls. The best of these walls, old and lichen-encrusted, will remain. The low, weathered, zig-zagging split rail fences also will remain; they work remarkably well for protecting planting beds, and they do their job unobtrusively.

Fremontodendron californicum ‘Margo’, a new cultivar recently introduced by the garden, differs from the famous Pine Hill fremontia (F. decumbens) in its larger, deeper yellow flowers

Fremontodendron californicum ‘Margo’, a new cultivar recently introduced by the garden, differs from the famous Pine Hill fremontia (F. decumbens) in its larger, deeper yellow flowers

Preservation and Education

Since its founding, the garden has been dedicated to the horticultural preservation of rare and endangered plants. Only recently have we had the opportunity to do what garden preservation is ultimately designed for: reintroduction to the wild. A botanical garden can be seen as an ark, temporarily holding threatened plants until better times, propagating and increasing them, and reintroducing (or relocating) them when safe wild havens can be secured. Walter Knight did this in 1966 when he sowed seed of the Antioch primrose on Brannan Island, and later on Brown’s Island, in the Sacramento River Delta. More recently, we have worked with San Mateo County parks staff to reintroduce to San Bruno Mountain one plant that was completely extinct in the wild — Leo Brewer’s manzanita (Arctostaphylos uva-ursi var. leobreweri) — and two that were locally extinct but that had been collected originally on the mountain before it became a park — San Francisco dune tansy (Tanacetum douglasi (T. camphoratum) and Pacific may lily (Maianthemum dilatatum).

Botanical gardens can prepare for opportunities of this kind by collecting seeds from plants at the range limits of their species, or in areas where a species is rare, although it may be common elsewhere. Even a common plant is best collected where it is rare, for that is where it is most likely to be eradicated, whether by human ignorance or greed or by climatic change.

Botanic garden facilities and talents also can be used for enhancement of existing populations. For example, we have been propagating Alameda manzanita (Arctostaphylos pallida), which is on the state list of endangered plants, to expand one of its two populations (at Huckleberry Regional Botanic Preserve in the Oakland hills) onto suitable sites nearby and to replace ancient individuals that had died out as the chaparral ecosystem aged. This kind of work is for us among the most satisfying we can pursue.

The garden produces a journal, The Four Seasons, which at the time of Dr Bacigalupi’s writing, was in volume one. In December 1991 we began volume nine. The journal is an important vehicle for research on manzanitas, and it also publishes technical and popular papers on all aspects of native plants.

In addition to the many plants introduced to the trade over the years (including the well known Garrya elliptica ‘James Roof’), our plant sales make available to the public horticultural treasures not commonly found in nurseries. We also offer a slide-lecture series on Saturdays in winter, so that mountain-starved lowlanders can go to the field, at least vicariously, even if the roads are buried in snow. The garden’s collections are a living laboratory, used year round by classes of all ages. Countless students receive their basic training here.

And for all visitors, the garden provides a protected, secluded, and peaceful haven for studying, strolling, picnicking, birdwatching, contemplating, or napping. Many people feel that the best time to visit the garden is in spring, when so much is in bloom, but you should not miss the fall color — or the winter color with bright-twig dogwoods, buttonwillows, and willows and the fragrant blooms of manzanitas. And there is nothing quite like the day after a big rainstorm, when the whole place is dashing with water and everything is fresh, and you wonder if you have ever really breathed before. For a while you may be liberated from that familiar longing to be striding across the barrens of an alpine pass. No need; you are already there.