Proposed Street Tree Species List Changes for 2018

Representatives from San Francisco Public Works, Friends of the Urban Forest, the Department of the Environment, and other local experts contributed to the following proposed changes for the 2018 Street Tree Species.

Background: The street tree list is broken into three sections:

1) Section 1: Tree species, varieties, and cultivars that do well in most locations in San Francisco 2) Section 2: Tree species, varieties, and cultivars that do well with certain special consideration 3) Section 3: Tree species, varieties, and cultivars that are experimental

In addition to the changes to each section outlined below, common names for each species were added to the list.

Section 1

Botanical Name Common name Source Size Type Additions Crataegus phaenopyrum Washington hawthorn promoted from S2 small D Melaleuca quinquenervia broad-leaf paperbark promoted from S2 medium E Olea europaea (fruitless cultivars) fruitless olive promoted from S2 medium E Podocarpus gracilior/ Afrocarpus falcatus fern pine promoted from S2 medium E 'D.D. Blanchard' cultivar added to Magnolia grandiflora

Reassigned Arbutus 'Marina' strawberry tree demoted to S2 small E Ceanothus 'Ray Hartman' California lilac tree demoted to S2 small E Cordyline australis cabbage tree demoted to S2 small E

Deleted Prunus serrulata 'Kwanzan' flowering cherry small D 'Bloodgood' and 'Yarwood' cultivars removed from Platanus x acerifolia

KEY new promoted demoted removed changed D = deciduous E = evergreen

Section 2 Botanical name Common name Source Size Type Additions Arbutus 'Marina' strawberry tree demoted from S1 small E Ceanothus 'Ray Hartman' California lilac tree demoted from S1 small E Cordyline australis cabbage tree demoted from S1 small E promoted from Quercus tomentella island oak S3 large E Melaleuca linariifolia flax-leaf paperbark NEW medium E Koelreuteria bipinnata Chinese flame tree NEW medium D

Reassigned Crataegus phaenopyrum Washington hawthorn promoted to S1 small D Melalueca quinquenervia broad-leaf paperbark promoted to S1 medium E Olea europaea (fruitless cultivars) fruitless olive promoted to S1 medium E Podocarpus gracilior/ Afrocarpus falcatus fern pine promoted to S1 medium E Acer rubrum 'Armstrong' columnar red maple demoted to S3 large D Eucalyptus polyanthemos silver dollar gum demoted to S3 large E Liriodendron tulipifera tulip tree demoted to S3 large D Melalueca styphelioides prickly-leaf paperbark demoted to S3 medium E

Deleted Acacia baileyana Bailey's acacia medium E Agonis flexuosa 'After Dark' After Dark peppermint tree medium E Liquidambar styraciflua American sweetgum large D Pittosporum crassifolium karo small E Pittosporum eugenioides tarata/lemonwood medium E Prunus cerasifera 'Krauter Vesuvius' purple-leaf plum small D Pyrus calleryana 'New Bradford' New Bradford pear medium D Tristaniopsis laurina 'Elegant' elegant tristania/elegant water gum small E

Other Geijera parvifolia moved from "medium" to "large" Metrosideros exelsa moved from "medium" to "large" Brahea edulis moved from "large" to "medium"

KEY new promoted demoted removed changed D = deciduous E = evergreen

Section 3: Botanical name Common name Source Size Type Additions Aesculus hippocastanum horse chestnut NEW medium D Agonis flexuosa 'Burgundy' Burgundy peppermint willow NEW medium E Archontophoenix cunninghamiana king palm NEW medium palm Brachychiton acerifolius flame tree NEW large E Brahea clara Mexican blue palm NEW medium palm Butia odorata southern jelly palm NEW small palm Ceanothus 'Cliff Schmidt' California lilac tree NEW small E Ceanothus arboreus California lilac tree NEW small E Ceratonia siliqua carob tree NEW large E Corymbia maculata spotted gum NEW large E Corymbia papuana ghost gum NEW large E Eucalyptus nicholii willow-leaf peppermint NEW large E Howea forsteriana Kentia palm NEW medium palm Melaleuca ericifolia swamp paperbark NEW medium E Melaleuca squamophloia scaly paperbark NEW medium E Parajubaea sunkha Sunkha palm NEW medium palm Parajubaea torallyi Bolivian mountain coconut NEW large palm Platanus racemosa 'Roberts' California sycamore, Roberts NEW large D Prunus subhirtella 'Autumnalis' Higan cherry NEW small E Quercus agrifolia coast live oak NEW large E Quercus coccinea scarlet oak NEW large E Tilia tomentosa silver linden NEW large D Trachycarpus fortunei Chinese windmill palm NEW medium palm Trachycarpus fortunei 'Wagnerianus' Chusan windmill palm NEW medium palm Acer rubrum 'Armstrong' columnar red maple demoted from S2 large D Liriodendron tulipifera tulip tree demoted from S2 large D Melaleuca styphelioides prickly-leaf paperbark demoted from S2 medium E

Reassigned Quercus tomentella island oak promoted to S2 large E

KEY new promoted demoted removed changed D = deciduous E = evergreen

2018 Recommended Street Tree Species List San Francisco Urban Forestry Council Approved [date]

The Urban Forestry Council annually reviews and updates this list of trees in collaboration with public and non-profit urban forestry stakeholders, including San Francisco Public Works – Bureau of Urban Forestry and Friends of the Urban Forest.

While this list recommends species that are known to do well in many locations in San Francisco, no tree is perfect for every potential tree planting location. This list should be used as a guideline for choosing which street tree to plant but should not be used without the help of an arborist or other tree professional.

All street trees must be approved by Public Works before planting. The application form to plant a street tree can be found on their website: http://sfpublicworks.org/plant-street-tree Photo by Scott Szarapka on Unsplash

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Section 1: Tree species, varieties, and cultivars that do well in most locations in San Francisco. Size Evergreen/ Species Notes Deciduous Small Evergreen Laurus nobilis ‘Saratoga’ Saratoga bay laurel Uneven performer, prefers heat, needs some Less than wind protection, susceptible to pests 20’ tall at Magnolia grandiflora ‘Little Gem’ Little Gem magnolia maturity Deciduous Crataegus phaenopyrum Washington hawthorn Subject to pests, has thorns, may be susceptible to fireblight. Medium Evergreen Agonis flexuosa (green) peppermint willow Standard green-leaf species only. ‘After Dark’ 20-35’ tall variety NOT recommended. Fast grower – at more than 12” annually, requires extensive maturity maintenance when young. Callistemon viminalis weeping bottlebrush Has sticky flowers Magnolia grandiflora ‘St. Mary,’ southern magnolia Melaleuca quinquenervia broad-leaf paperbark Grows fast, dense, irregular form, prefers wind protection Olea europaea (any fruitless variety) fruitless olive Needs a very large basin, prefers wind protection Podocarpus gracilior/Afrocarpus falcatus fern pine Slow rooter. Tristaniopsis laurina tristania; water gum Standard species only. ‘Elegant’ variety NOT recommended. Formerly known as Tristania laurina, slow grower – less than 6” annually Large Evergreen Lagunaria patersonii primrose tree Grows well in windy areas More than Lophostemon confertus Brisbane box Formerly Tristania conferta, fast grower 35’ tall at Magnolia grandiflora ‘Sam Sommers,’ southern magnolia maturity ‘Majestic Beauty,’ ‘D.D. Blanchard’ Pittosporum undulatum victorian box Self-sows, do not plant near natural areas Deciduous Ginkgo biloba ‘Autumn Gold,’ ‘Princeton ginkgo; maidenhair Slow grower, prefers wind protection Sentry,’ ‘Saratoga’ Platanus x acerifolia ‘Columbia’ London plane; sycamore Prefers wind protection, susceptible to anthracnose and powdery mildew Ulmus parvifolia ‘Drake,’ ‘Sempervirens’ Chinese elm Fast grower, requires extensive pruning and maintenance

2 Section 2: Tree species, varieties, and cultivars that do well with certain special considerations; may not appropriate for planting broadly throughout San Francisco. Size Evergreen/ Species Notes Deciduous Small Evergreen Arbutus x ‘Marina’ strawberry tree Fruit drop can range from low volume to Less than significant. May be short lived; may need to 20’ tall at be replanted in 20-25 years maturity Callistemon citrinus lemon bottlebrush Grows low, and wide canopy and needs a wide sidewalk, sticky flowers Ceanothus ‘Ray Hartman’ California lilac tree Not good for narrow sidewalks

Cordyline australis Cabbage tree Needs very large basin, take care when planting near natural areas Elaeocarpus decipiens Japanese blueberry Slow growing, keep out of strong/prevailing wind, flowers but may not produce fruit at maturity Leptospermum laevigatum Australian tea tree Poor rooter, may not root well in sandy soil. Magnolia doltsopa sweet michelia Formerly Michelia doltsopa; uneven performer, grafted trees grows very slowly, prefers heat, wind protection Magnolia champaca/M. x alba champak Formerly Michelia champaca; needs wind protection, wide sidewalk, gets powdery mildew and very slow grower Pyrus kawakamii evergreen pear Plant in only warmest areas of city, semi- evergreen, leaf spot/fungus likely to occur and may cause premature leaf drop, does not flower well in our climate, susceptible to fireblight Deciduous Acer buergerianum trident maple Prefers heat, wind protection Medium Evergreen Brahea edulus Guadalupe palm Palm tree. Very slow growing in San 20-35’ tall Francisco, needs a large basin. at Eriobotrya deflexa bronze loquat Needs wind protection, does not perform maturity well in sandy soils, susceptible to fireblight Jacaranda mimosifolia jacaranda Uneven performer; prefers heat, wind protection, good drainage; spring leaf drop flax-leaf paperbark Melaleuca linariifolia (NEW) Phoenix dactylifera ‘Medjool’ or ‘Zahidi’ date palm Needs a large basin and wide sidewalk 3 Syagrus romanzoffiana queen palm Needs heat, wind protection Deciduous Aesculus x carnea red horse chestnut gets windburn easily in summer even in protected sites Koelreuteria bipinnata Chinese flame tree NEW Koelreuteria paniculata golden raintree Uneven performer, prefers heat, wind protection Pistacia chinensis ‘Keith Davey’ or Chinese pistache Prefers heat, wind protection standard Large Evergreen Corymbia ficifolia red flowering gum Needs a very large basin, wide sidewalk, More than drops large seed pods 35’ tall at Geijera parvifolia Australian willow Prefers heat, wind protection maturity Hymenosporum flavum sweetshade Uneven performer, prefers heat, wind protection, good drainage Lyonothamnus floribundus asplenifolius Catalina ironwood Prefers heat, wind protection, prone to transplant shock, very susceptible to phytophthora Metrosideros excelsa New Zealand Christmas tree Needs a very large basin, and very wide sidewalks Quercus suber cork oak Needs a large basin, wide sidewalk Quercus tomentella island oak Availability improving Washingtonia robusta Mexican fan palm Prefers some warmth Deciduous Tilia cordata little-leaf linden Susceptible to aphids and sooty mold.

4 Section 3: Tree species, varieties, and cultivars which are experimental or potentially problematic. San Francisco does not have many of these species planted yet and would like to plant more of these trees to test how they do. *Permission from the Bureau of Urban Forestry is required to plant any species below. Approval is will vary depending on the planting site. Size Evergreen/ Species Common Name Notes Deciduous Small - Evergreen Butia odorata southern jelly palm NEW Less than Ceanothus ‘Cliff Schmidt’; Ceanothus California lilac tree NEW 20’ tall at arboreus maturity Prunus lyonii Catalina cherry Fruit drop may get messy Eucalyptus conferruminata/E. lehmanni bushy yate Wide canopy – large space needed Deciduous Crataegus x lavallei Lavalle hawthorn Appears to be less susceptible to fireblight and other pests than other Crataegus Prunus subhirtella ‘Autumnalis’ Higan cherry NEW; tolerates mild winters better than other flowering cherry species Medium Evergreen Agonis flexuosa ‘Burgundy’ Burgundy peppermint willow Better form and structure than other dark- 20-35’ tall leaf cultivars; fast grower at Archontophoenix cunninghamiana king palm NEW; needs wind protection and water maturity Banksia integrifolia coast banksia Requires extensive early maintenance Brahea clara Mexican blue palm NEW Brachychiton populneus bottle tree Prefers heat and wind protection, needs a large basin due to thick trunk Cassia leptophylla gold medallion tree Semi-evergreen, requires extensive early maintenance Cedrella fissilis Brazilian cedarwood Ceiba speciosa silk floss tree Prefers heat, wind protection Howea forsteriana Kentia palm NEW Melaleuca ericifolia swamp paperbark NEW Melaleuca squamophloia scaly paperbark NEW Melaleuca styphelioides prickly-leaf paperbark Can root poorly, and prickly leaves Parajubaea sunkha Sunkha palm NEW Pittosporum rhombifolium/ Queensland pittosporum Use in warmer parts of the City Auranticarpa rhombifolia Trachycarpus fortunei, standard & Chinese windmill palm NEW ‘Wagnerianus’ Cupaniopsis anacardioides carrotwood Uneven performer; needs heat & wind protection

5 Deciduous Aesculus hippocastanum horse chestnut Celtis sinensis Chinese hackberry Prefers heat, wind protection, uneven performer, gets pests Corylus colurna Turkish hazel Large Evergreen Brachychiton acerifolius flame tree NEW: semi-deciduous More Ceratonia siliqua carob tree NEW: needs large basin & wide sidewalk than 35’ Corymbia maculata/Eucalyptus m. spotted gum NEW tall at Corymbia papuana/Eucalyptus p. ghost gum NEW: Reqs. warmth; possible lignotubers maturity Eucalyptus nicholii willow-leaf peppermint NEW Eucalyptus polyanthemos silver dollar gum Needs a large basin, fast grower, high maintenance Parajubaea torallyi Bolivian mountain coconut palm NEW Quercus agrifolia coast live oak NEW; Requires large sidewalk/basin and wind protection; likely unsuitable for most street tree locations. Quercus ilex holly oak Needs wind protection, sidewalk space, gets powdery mildew Quercus virginiana southern live oak Quillaja saponaria Chilean soapbark Availability improving Deciduous Acer x freemanii Freeman maple Acer rubrum ‘Armstrong’ columnar red maple Prefers heat Liriodendron tulipifera tulip tree Uneven performer, susceptible to aphids followed by sooty mold. Platanus x acerifolia ‘Liberty’ London plane, sycamore Prefers wind protection, susceptible to anthracnose and powdery mildew Platanus racemosa ‘Roberts’ California sycamore (Roberts) NEW Quercus coccinea scarlet oak NEW Quercus frainetto ‘Forest Green’ Italian oak Quercus phellos willow oak Tilia tomentosa silver linden NEW Ulmus parvifolia x carpinifolia ‘Frontier’ frontier elm Ulmus propinqua ‘Emerald Sunshine’ emerald sunshine elm Ulmus wilsoniana ‘Prospector’ prospector elm Ulmus japonica x wilsoniana ‘Accolade’ accolade elm Zelkova serrata Japanese zelkova Needs wide sidewalk

*For more information about planting trees under and around power lines, visit the Right Tree, Right Place website: http://www.pge.com/en/mybusiness/services/maint/vegman/customerresources/righttree/index.page 6