Arboretum

Learn more about the plants and trees you can see on the Dunn School campus. 

Hesperoyucca whipplei/Our Lord’s Candle/Chaparral yucca

Chaparral Yucca (Yucca), a spiky, succulent shrub, native to southern California and Baja Mexico, grows
in Chaparral, Coastal Sage Scrub, and Oak Woodland plant communities. Yucca requires 5-10 years to reach maturity, noted by a 10–15-foot-tall spectacular flowering spike displaying bell shaped, purplish flowers. Yucca is dependent on its relationship with the nocturnal Yucca Moth (Tegeticula species) for
flower pollination. Before flowering, plants produce smaller plants, ‘pups’, genetically identical to the
original. Once pollinated, Yucca’s life cycle starts again: the plant dies while the stalk will remain upright
for years.

Yucca’s distinct features include parallel leaf veins which extend from the base to the tip of each leaf
(typical of a monocot). Yucca’s veining pattern allows the plant to be a useful source of natural fiber
obtained by pounding leaves until they split apart into fibrous strands. The fiber is used to make
materials such as sandals, cloth, and rope. Indigenous people use Yucca for fiber and food; its base,
seeds, and fruits are edible.

Plant Type: Succulent

Size: 2-12’ Tall, 2-3’ Wide

Form: Fountain

Growth Rate: Moderate

Dormancy: Summer Semi-deciduous

Fragrance: Slight

Flower Color: Cream, pink, purple, white

Flowering Season: Spring, summer

Supported Wildlife: Yucca moth, Tegeticula sp. with which it has co evolved, California Thrashers, butterflies and other insects such as Yucca Giant-Skipper, Navel Orangeworm

Landscaping information:

Sun: Full sun 

Water Requirements: Extremely low to very low water (maximum once-a-month supplemental summer irrigation, once established)

Soil Drainage: Fast 

Common Uses: Ground cover, deer resistant, bird gardens

Reference:

https://calscape.org/loc-California/Hesperoyucca%20whipplei%20(Chaparral%20Yucca)?newsearch=


 

Opuntia basilaris/Prickly Pear

Beavertail Prickly Pear Cactus, (Prickly Pear) is a spiny, padded cactus native to southern California and Baja California. Prickly Pear features yellow, pink, or red flowers turning into edible, purplish red fruits. Glochids, small, barbed bristles which easily penetrate and irritate the skin, cover Prickly Pear’s fruits and pads in clumps and surrounding spines. 

Plant Type: Shrub, Succulent

Size: 3.3’ Tall

Growth Rate: Moderate

Fragrance: Pleasant

Flower Color: Yellow, purple, or red

Flowering Season: Spring

Supported wildlife: Birds and insects such as caterpillars, butterflies (example Dyotopasta yumaella)

Landscaping information:

Sun: Full sun 

Water Requirements: Very low

Soil Drainage: Fast, preferring sand or sandstone areas

Common uses: Hedges, deer resistant, bird gardens

Information derived from:

https://calscape.org/loc-California/Prickly%20Pear%20(Opuntia%20littoralis)?newsearch=1

 


 

Quercus lobata/White Oak/Valley Oak

Valley Oak, a mighty California oak often reaches 70 feet or taller with equal or greater spread, is possibly the largest North American oak tree. Because of its grand size, Valley Oaks are planted successfully in large landscape settings and may live six hundred years.

Valley Oak distinguishes itself from its cousin, Coast Live Oak, by bark patterns, leaf shape, and texture. Valley Oak’s bark is more uniform than the ridged, alligator-like hide of Coast Live Oak. Valley Oak’s species name, ‘lobata,’ comes from the deeply rounded, lobed-leaf edges which also distinguish it from Coast Live Oak. Valley Oak leaves have a slightly fuzzy, velvety texture, pale green underside and matte green top, and measure twice as long as wide. Valley Oak leaves turn yellow in fall before turning dull brown and falling off entirely in winter. 

Valley Oak performs best away from any regularly irrigated garden areas. Even within 30 feet of irrigated planting beds, the additional water may cause limbs to become heavy and break. Its roots seek out water sources and do well located near streams and ponds.

Valley Oak grow in large, open land areas creating the scenic, and now rare, ‘Oak Savanna’ (Savanna). In Savannas, Valley Oak naturally distance themselves with enough space to reach their largest form growing unrestricted in any direction by competing trees. Valley Oaks prefer drier areas on south and southwest facing slopes and flats, and the Savannas create a picturesque, silhouetted pattern of fully formed trees, widely spaced, growing amid native grasslands. 

Plant Type: Tree

Size: 60-100’ tall, 50’ Wide

Growth Rate: Fast, moderate

Dormancy: Winter deciduous

Fragrance: Pleasant

Flower Color: Cream, yellow, green

Flowering Season: Spring, winter

Supported wildlife: Mammals, birds, and insects, among many such as squirrels, butterflies, caterpillars (Mournful Duskywing, Elegant Sheepmoth)

Landscaping information:

Sun: Full sun 

Water Requirements: Low (maximum once-a-month supplemental summer irrigation, once established)

Soil Drainage: Medium

Common uses: Deer resistant, bird garden, butterfly garden

Reference:

https://calscape.org/loc-California/Quercus%20lobata%20(Valley%20Oak)?newsearch=1


 

Quercus agrifolia/Red Oak/Coast Live Oak

Coast Live Oak (Live Oak) is a long-living, evergreen, iconic California oak, native to southern California. Shorter than the Valley Oak, Live Oak often starts-out scrubby and gangly when young and matures into variable forms with many branches. Live Oak leaves are concave, waxy, oval, and dark green with spiny leaf-edges designed for maximum solar-ray absorption. 

Live Oaks establish themselves in Oak Woodlands where multiple trees intersect, their trunks support branches which twist and bend searching for sunlight. Live Oaks typically inhabit north and northeastern facing slopes, coastal hills, plains, and near perennial streams. 

Live Oaks sprout readily from acorns which land in shaded, well-mulched, leaf littered locations. Live Oaks prefer dry conditions under their canopies, stretching their roots to water sources keeping the area closest to the trunk dry. They prefer their own leaves as mulch covering their roots which results in a buildup of mycorrhizal fungi and do not require added fertilization once established. 

Plant Type: Tree

Form: Highly varied shape, scrubby when young growing into medium sized tree with rounded, dense crown

Size: 25-82’ Tall, 15-35’ Wide

Growth Rate: Moderate to slow

Dormancy: Evergreen

Fragrance: None

Flower Color: Cream, yellow, green

Flowering Season: Spring, winter

Supported wildlife: Birds, butterflies, caterpillars (Mournful Duskywing, California Sister, Polyphemus moth, among many others)

Landscaping information:

Sun: Full sun, part shade 

Water Requirements: Low (maximum once-a-month supplemental summer irrigation, once established)

Soil Drainage: Medium

Common uses: Bank stabilization, hedges, deer resistant, bird gardens, butterfly gardens 

Reference: 

https://calscape.org/loc-California/Quercus%20agrifolia%20(Coast%20Live%20Oak)?newsearch=1

 


 

Quercus douglasii/Blue Oak/Mountain Oak/Iron oak

Blue Oak, a medium-sized, irregularly shaped, deciduous tree, populates California’s coastal ranges. Appearing greener and bluer than other oaks, its dark blue-green leaf tint forms a striking contrast to the Blue Oak’s light gray, almost white, bark. 

The most drought tolerant of California oaks, Blue Oak tends to support a smaller canopy than its cousins, investing more energy into root growth. In addition to California coastal ranges, Blue Oak commonly inhabits Sierra Nevada foothills along with Gray Pine (Pinus sabiniana) and completely encircles the Central Valley from Shasta to Los Angeles County. 

Plant Type: Tree

Form: Upright, rounded, upright columnar

Size: 16-82’ Tall, 30’ Wide

Growth Rate: Slow

Dormancy: Summer semi-deciduous, winter deciduous

Fragrance: None

Flower Color: Cream, yellow, green

Flowering Season: Spring

Supported wildlife: Birds, butterflies, caterpillars (California sister, Propertius Duskywing, Mournful Duskywing, others)

Landscaping information:

Sun: Full sun, part shade 

Water Requirements: Low (maximum once-a-month supplemental summer irrigation, once established)

Soil Drainage: Fast

Common uses: Bank stabilization, deer resistant, bird gardens, butterfly gardens

Reference: 

https://calscape.org/loc-California/Quercus%20douglasii%20(Blue%20Oak)?newsearch=1

https://www.fs.fed.us/database/feis/plants/tree/quedou/all.html 


 

Quercus Suber/Cork Oak

Cork Oak, an oak tree native to western Africa and southwestern Europe, is distinctive for its spongy bark, used to make bottle stoppers, flooring, and other items for generations. Cork consists of dead plant cells, cellulose macromolecule suberin, a macromolecule which is highly hydrophobic (water-repelling) and slightly rubbery. Because of its water-repelling, dense composition, Cork Oak bark insulates for heat, sound, and repels water.

Cork Oak bark is carefully harvested without power tools. Harvesting is a process involving skilled workers and occurs once the tree reaches 25-30 years old, then every 9-11 years, up to 12 times during the tree’s lifetime. Skilled workers gradually remove several inches of bark at a time. The first- and second-year harvests are typically used for flooring or insulation, respectively. The third and fourth harvests are considered the best quality, yielding the most versatile cork. 

Cork Oak’s leaves are leathery and alternately placed and the tree produce acorns in clusters 2-4.6 cm long. The trunk is deeply textured and ridged deeply and withstands frost and high air temperatures, enduring drought by reducing its metabolism. 

Plant Type: Tree

Size: 50-70’ Tall, 40-50’ Wide

Growth Rate: Moderate

Dormancy: Evergreen

Fragrance: None

Flower Color: Cream, yellow, green

Flowering Season: Spring

Supported wildlife: Birds, moths, butterflies

Landscaping information:

Sun: Full sun 

Water Requirements: Low (maximum once-a-month supplemental summer irrigation, once established)

Soil Drainage: Fast

Common uses: Hedges, specimen plant

Reference: 

https://plantmaster.com/plants/eplant.php?plantnum=541

https://en.wikipedia.org/wiki/Quercus_suber


 

Salvia apiana/White Sage

White Sage is a perennial shrub native to southern California and Baja California and typically found in Coastal Sage Scrub habitat. Coastal Sage Scrub habitats occur primarily in dry, foggy areas along coastal and inland areas where the marine layer reaches into foothills and canyons. The leaves, light green when new, turn silver white as they age. White Sage, called we’wey and considered sacred by Chumash people, is edible and used for ceremonial and medicinal purpose. White Sage seeds when ground make ‘pinole’ and represents a staple food for native California tribes. 

Because of ‘smudge stick’ popularity,’ White Sage and surrounding habitat suffer from illegal plant harvesting on private and public lands. Although White Sage is not currently listed by California Fish and Wildlife as threatened or endangered, its survival is challenged by poaching, development, climate change, drought, and wildfire.

Plant Type: Shrub

Size: 3-5’ Tall, 3-8’ Wide

Form: Mounding

Growth Rate: Fast, moderate

Dormancy: Summer Semi-deciduous

Fragrance: Pleasant

Flower Color: White, or lavender spotted

Flowering Season: Winter, spring, summer

Supported wildlife: Hummingbirds, carpenter bees, bumble bees, insects (Alfalfa looper moth, Bilobed looper moth, Wavy lined emerald, Hawaiian beet webworm, others)

Landscaping information:

Sun: Full sun, 

Extremely low to very low water requirements (max 1x month summer irrigation once established)

Soil Drainage: Fast to medium preferred

Common uses: Bank stabilization, groundcover, Bird/insect gardens

Reference:

https://calscape.org/loc-California/White%20Sage%20(Salvia%20apiana)?newsearch=1

 


 

Parkinsonia microphylla/ Foothill Palo Verde

Palo Verde, a distinctive, green-barked tree is native to the southwestern United States, southeastern California, southern Arizona, and northwestern Mexico. It is slow-growing, long-lived and mostly found on rocky slopes. The green trunk allows for photosynthesis when the tree is leafless. Because of Palo Verde’s sculptural quality, it is often used as an accent, rather than a shade tree. Its yellow-greenish leaves are very tiny and drop during excessively dry and or hot periods. While new growth on Palo Verde is thorny, the ‘Desert Museum’ cultivar is grown for its thornless habit and longer flowering season. As part of the Fabaceae (Legume) family, Palo Verde forms long pea-like seed pods and is a nitrogen-fixing plant providing needed nitrogen to the soil. Because of ‘smudge stick’ popularity,’ White Sage and surrounding habitat suffer from illegal plant harvesting on private and public lands. Although White Sage is not currently listed by California Fish and Wildlife as threatened or endangered, its survival is challenged by poaching, development, climate change, drought, and wildfire.

Plant Type: Tree

Size: 8.2-16.4’ Tall, 12’ Wide

Growth Rate: Fast, moderate

Dormancy: Summer Semi-deciduous

Fragrance: None

Flower Color: Cream, yellow, green

Flowering Season: Spring

Supported wildlife: Hummingbirds, insects (Forsebia moth, Juno buckmoth, The Darter moth), pods useful for mammals

Landscaping information:

Sun: Full sun 

Water Requirements: Extremely low to very low water (maximum once-a-month time supplemental summer irrigation, once established)

Soil Drainage: Fast

Common uses: Hedges, specimen plant

Reference: 

https://calscape.org/loc-California/Foothill%20Palo%20Verde%20(Parkinsonia%20microphylla)?newsearch=1


 

Parkinsonia praecox/Palo Brea/Sonoran Palo Verde

Palo Brea is an umbrella-shaped tree with spreading, pendulous, branches, inhabits California’s southwest desert, Mexico, and areas of Columbia, Peru, and Ecuador. In spring, masses of yellow flowers are followed by light brown seed pods. Palo Brea, often selected as a large, specimen tree, is most successful planted where it can grow to full width without pruning. With its green trunk, Palo Brea photosynthesizes even when leaves drop during exceptionally hot and dry weather. The leaves are small, pinnate (leaflets on either side of the stem), and green. 

Plant Type: Tree

Form: Umbrella, spreading branches, low hanging 

Size: 20-25’ Tall, 18-24’ Wide

Growth Rate: Fast, moderate

Dormancy: Summer, Semi-deciduous

Fragrance: None

Flower Color: Yellow

Flowering Season: Spring

Landscaping information:

Sun: Full sun 

Wildlife supported: Native birds

Water Requirements: Extremely low to very low water (maximum once-a-month time supplemental summer irrigation, once established)

Soil Drainage: Requires well-drained soil

Common uses: Large open areas as specimen plant

Reference: 

https://www.public.asu.edu/~camartin/plants/Plant%20html%20files/parkinsoniapraecox.html

 


 

Metasequoia glyptostroboides/ Dawn Redwood/ Water Fir

Dawn Redwood, the shortest redwood and native to south central China, inhabits wet, lower slopes, and along stream valleys. As a deciduous conifer, it loses its needles in the fall which turn a bronzy red before dropping. Dawn Redwood was thought to be extinct because only fossil records remained until the 1940’s when a living specimen was identified in central China.

Plant Type: Tree

Size: 60- 100’ tall, 25-40’ wide

Growth Rate: Fast

Dormancy: Winter deciduous

Fragrance: None

Flower Color: Inconspicuous flowers 

Foliage: Dark green to light green, opposite branching pattern with branchlets of long, simple needles that appear flattened 

Flowering Season: Spring, inconspicuous

Landscaping information:

Sun: Full sun 

Water requirement:  Medium to high 

Soil Type: Sandy, loamy, rocky 

Common uses: Specimen plant, privacy screen, windbreak, wildlife garden

Reference: 

https://plantmaster.com/plants/eplant.php?plantnum=25738


 

Cedrus deodara/Deodar Cedar

Deodar Cedar is a conical-shaped, cone-bearing, evergreen tree with pendulous, spreading branches. Deodar Cedar is easily identified because it uppermost branches delicately tilt downwards at the tips. Native to east-Afghanistan, southwestern Tibet, western Nepal, northern Pakistan, and northern central India, Deodar Cedar is heat and drought tolerant once established. 

Plant Type: Tree

Size: 60- 100’ Tall, 40-60’ wide

Growth Rate: Fast, moderate

Dormancy: Evergreen

Fragrance: None

Flower Color: Inconspicuous flowers 

Foliage: Light silvery green needles, about two” long 

Flowering Season: Spring, barrel shaped cones in fall and winter

Landscaping information:

Sun: Full sun 

Water Requirements: Medium

Soil Type: Sandy, clay, unparticular 

Common uses: Specimen plant, privacy screen, windbreak, wildlife garden

Reference: 

https://plantmaster.com/plants/eplant.php?plantnum=123

 


 

Cedrus atlantica/Atlantic Cedar

Atlantic Cedar, an evergreen, cone-bearing tree, native to northern Africa and the Middle East, establish mountainside forests in its native habitat. Atlantic Cedar has blunted, short needles, about one inch long. The glaucous variety commonly used as a landscape plant, features bluish greenish leaves adding interesting color and texture to the garden. Because of is aromatic oils, it is useful as a natural insect deterrent. Atlantic Cedar is a long-lived tree, known to survive 150 years.

Plant Type: Tree

Size: 25-60’ Tall, 25-40’ Wide

Growth Rate: Moderate to slow

Dormancy: Evergreen

Fragrance: None

Flower Color: N/a, Inconspicuous flowers

Flowering Season: Spring pollen

Supported wildlife: Birds, mammals

Landscaping information:

Sun: Full sun

Water requirements: medium, more tolerant of hot and dry than most cedars

Soil Type: Sandy, clay, loam, rocky, unparticular about soil type

Common uses: Specimen plant, windbreak

Reference: 

https://plantmaster.com/plants/eplant.php?plantnum=120


 

Sequoia sempervirens/ Coast Redwood

Coast Redwood is a coastal redwood species and famously includes the tallest trees on earth. Habitat ranges from northern California to southwestern Oregon. This region provides wet winters and cool foggy summers best suited for this tree; summer fog drip is important to the trees’ overall water budget. Because of adequate water within its habitat, Coast Redwoods grow readily and quickly in their native range. Outside of their native range they show signs of stress with shortened lifespans because of sensitivity to poor air quality, low humidity, and drying winds. 

Plant Type: Tree

Size: 60-380’ Tall, 45’ Wide

Form: Upright, columnar

Growth Rate: Fast

Dormancy: Evergreen

Fragrance: Pleasant

Flower Color: Yellow to cream, though largely inconspicuous

Flowering Season: Fall, summer

Supported wildlife: Moths and caterpillars

Landscaping information:

Sun: Full sun, to part shade

Water requirements: Low, though summer fog drip is a crucial part of plant’s overall moisture requirement (in a landscape setting, summer irrigation of max one time per month once established)

Soil Type: Prefers deep woodland soil with high organic content, PH 6-7

Common uses: This tree is typically too large for most residential purposes, found growing from Monterey County to southern Oregon along moist forested area along the coast.

Reference:

https://calscape.org/loc-California/Sequoia-sempervirens-(Coast-Redwood)?srchcr=sc62828b5134834

 


 

Sequoia giganteum/Giant Redwood

Sequoia National Park in the Sierra Mountains received its name from these giants. The Giant Redwood include the world’s largest trees by volume, while not the tallest, they are impressive to behold as they are stout as well as tall. Also incredibly long lived, the oldest known Giant Redwood based on ring count, is 3,500 years old. Leaves are evergreen, awl-shaped, and arranged spirally on shoots. Their bark is fibrous, rough, and up to three-feet thick at the base providing fire protection to the type of fires typical of historical California. California’s present-day fires are significantly hotter, drier, and can be much more damaging to these iconic trees.

Plant Type: Tree

Size: 35-311’ Tall, 50-60’ Wide

Form: Pyramidal, upright, columnar

Growth Rate: Slow

Dormancy: Evergreen

Fragrance: Unpleasant

Flower Color: Green to cream, though largely inconspicuous

Flowering Season: Spring 

Landscaping information:

Sun: Full sun, to part shade

Water requirements: Low, fog drip is part of moisture requirement, (summer irrigation of max twice per month once established)

Soil Type: Prefers deep rich, PH 5-7

Common uses: This tree is typically too large for most residential purposes, found in the Sierra mountains in large groves on moist, west facing slopes, and in mountain valleys along with firs and pines.

Reference:

https://calscape.org/loc-California/Sequoia-sempervirens-(Coast-Redwood)?srchcr=sc62828b5134834