Arboretum Day 2022: Companion Trees and the Arboretum Heritage Project

It is our honor to extend a cordial in-person invitation to our third-annual Arboretum Day, here at Cypress Lawn Arboretum and Botanical Gardens on November 12th, 2022.

RSVPs to this special event, stewarding forward the legacy of our Memorial Park’s many trees, may be made here on our Heritage Foundation website.


Celebrating 130 years and 130 species in the living collection of the Arboretum, this special community event in our “Tree City USA” Town of Colma will showcase the diverse trees of the Memorial Park, honor our champion Monterey Cypress by the foundational entry archway, and continue our living legacy with the planting of companion trees for old heritage specimens along Cypress Avenue of our original East Campus.





Several heritage plantings of the Arboretum have thrived in this place, a key part of our Bay Area urban forest, for a century and beyond. Here in our Memorial Park, we cherish and celebrate our eldest trees, especially because we know these noble veterans will not be around forever. Despite their impressive longevity, as time goes on, the natural arboricultural symptoms of aging will surely come to pass.  Arborists and foresters know of this process as senescence.

The energy needed for resilient growth or the sealing of wounds may be less in post-mature trees. Oftentimes, veteran trees may even shed entire branch systems to conserve resources and extend their own lives, in a process called natural retrenchment. Even so, decay and decline, or death, are truly a part of the virtuous cycle of life, with people as with trees here in our garden cemetery.

In growing on through senescence, the trees share a story of wisdom, strength, and hope! In the forests — and in this urban forest landscape — veteran trees will occasionally produce a great number of seeds, as a late offering of resilience for future generations. The seedlings of tomorrow are often beginning their lives in the cones and fruits growing in the canopies of their elders.

In modern arboriculture, the idea of planting a companion tree champions this natural intention, with a bit of help from humanity to move things along. Placing a young tree of the same species, or genus, very near the location of its elder kin offers us all the hope of carrying forward a multi-generational heritage.

There are several benefits, both to the veteran and the youthful companion, in this planting process. For one, the transplant shock of a young tree adapting to the culture and conditions of its new home — wind, heat, and intense weather — may stress a seedling during the first few years of establishment. Planting it near the canopy, or in the lee, of a post-mature neighbor can offer some protection from the environmental extremes of the local climate.  The support of our elders is such a gift in this life, for people and trees alike.



Another support system may be found in the soil surrounding a veteran tree. Beneficial fungi in the ground, known as mycorrhizae, can promote healthy relationships in the root systems of young plantings. The mycelium network of fungus, hidden out of sight underground, lives as a community support system for trees young and old, throughout Cypress Lawn Arboretum. In these meaningful ways, the kinship of veteran companions may help the next generation find a good footing and establish a strong foundation in their new home.

In early November — the regionally appropriate time for planting here in the Mediterranean microclimate of coastal California — we will take the first steps towards introducing the next generation of trees in our cherished Arboretum.


The Arboretum Heritage Project will embrace the concept of companion trees to establish the forest of our future. Leading up to our Arboretum Day celebration, we will plant companion trees up and down the Avenue to accompany the following veterans:

  • Quercus suber | Cork oak, of the Mediterranean basin
  • Platanus x acerifolia | London planetree
  • Schinus molle | Peruvian pepper tree
  • Taxus baccata ‘Fastigiata’ | Irish yew
  • Corymbia ficifolia |Red-flowering gum, of Australia
  • Quercus agrifolia | Coast live oak, of California
  • Metrosideros excelsa | Pohutukawa, of New Zealand
  • Laurus nobilis | European laurel
  • Ginkgo biloba | Maidenhair, of China

On November 12th, you’re welcome to join us in the growing tradition of Arboretum Day, celebrating life both young and old here at Cypress Lawn. Our champion Hesperocyparis macrocarpa, located just inside the threshold of our 1892 archway, will be honored with a companion planting or two of its own.

With this gift of reciprocity to our most veteran trees, the heritage of the Arboretum may live and grow onwards, branching out in the seasons to come. Conserving the past by promoting the future — that is the mission of our burgeoning Arboretum Heritage Project. So come and take a walk, help us plant a tree, and perhaps we can all grow a little more together …