Arboretum

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.

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. 

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. 

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. 

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. 

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. 

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.

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.

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. 

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.

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. 

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.

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. 

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.