Tree Aeonium (Aeonium arborescens). A branched 3-foot-tall succulent, with rosettes of 2-3-inch spathulate (rounded end) leaves at the tips of stems. Yellow flowers form in long clusters in mid-spring to early summer.
Stonecrops plant family (Crassulaceae), native to the Canary Islands (Atlantic Ocean) and west coast of Morocco. (Courtesy Tom Karwin) Crimson Spot Rockrose (Cistus ladanifer) Upright shrub 5-6 feet with sticky slender dark green leaves grayish and fragrant in the heat of summer. The beautiful 3-4-inch-wide flowers are the largest of the Cistus genus.
The plant’s fragrant resin (gum labdanum) has been used in perfumes. Rock-rose plant family (Cistaceae), native to Southern Europe (Spain, Portugal). (Courtesy Tom Karwin) Globe Daisy (Globularia sarcophylla 'Blue Eyes') Shrubby perennial to 2 feet and 3-4 feet wide, with leathery, silver-green foliage.
From the early summer through fall, it creates attractive 1 in. “powder puff’ flowers, lavender white with cobalt centers. This cultivar is the natural hybrid of two species in the Globe Daisy plant family (Globulariaceae), native to the Canary Islands (Atlantic Ocean).
(Courtesy Tom Karwin) Mediterranean Spurge (Euphorbia characias wulfenii) This compact evergreen shrub grows up to 4 feet tall and, with many medium to tall unbranched stems with long narrow leaves, clothed densely in short hair (tomentose), and yellow floral nectar glands within the yellow cup-like cyathia (“false flower”), which are borne in large dense spherical to oblong clusters, from spring to early summer. This whole, highly specialized arrangement resembles a single flower. Spurge plant family (Euphorbiaceae), native to southern France.
(Courtesy Tom Karwin) Red-leaved Castor Bean (Ricinus communis ‘New Zealand Purple’) An evergreen herbaceous or semi-woody large shrub or small tree, growing 6-10 feet tall. The oversized, tropical-looking leaves and bizarre seed pods make this plant an exotic addition to the ornamental garden. The seeds (not true beans), used to produce castor oil, contain ricin, a naturally occurring carbohydrate-binding protein, that is highly toxic when inhaled, ingested, or injected.
Another member of the Spurge plant family (Euphorbiaceae), native to southeastern Mediterranean Basin, Eastern Africa, and India, and widely grown. (Courtesy Tom Karwin) Upright Rosemary (Salvia officinalis ‘Tuscan Blue’, previously known as Rosmarinus officinalis) An erect shrub 4-6 feet tall and 4-5 feet wide, with fine, aromatic, olive-green foliage. Bright lavender-blue flowers bloom in the winter through spring.
Rosemary is used as a decorative plant in gardens and its leaves are used in the fragrance industry and for flavoring various foods. A member of the large Mint or Sage plant family (Lamiaceae), native to the Mediterranean Region. (Courtesy Tom Karwin) Tree Aeonium (Aeonium arborescens).
A branched 3-foot-tall succulent, with rosettes of 2-3-inch spathulate (rounded end) leaves at the tips of stems. Yellow flowers form in long clusters in mid-spring to early summer. Stonecrops plant family (Crassulaceae), native to the Canary Islands (Atlantic Ocean) and west coast of Morocco.
(Courtesy Tom Karwin) In this column, we have often referred to the world’s five “Mediterranean climate” regions: the Mediterranean Basin, South Africa, Chile’s western coast, Australia’s southwestern coast and the California Floristic Province. To be clear, the California Floristic Province excludes the state’s southern desert areas and extends a bit into Oregon’s west coast and Baja California. These five regions, also called “summer-dry” regions, have similar climates.
The practical effect of this similarity is that people living in one of the regions, e.g., the California Floristic Province, could garden readily and easily with plants from the other summer-dry regions.
Each of these five regions has numerous unique plants that have evolved naturally within the region, creating opportunities for gardeners to introduce climate-compatible exotic plants into their gardens, and to grow them successfully. Gardeners interested in exotic plants could explore plants from areas other than the summer-dry regions. Gardening in mild-climate environments, such as the Monterey Bay region, could grow plants from any of the summer-dry regions.
Some exotic introductions might require special care during periods of higher or lower temperatures for which the plants are unaccustomed. The readers of this column could have a horticultural interest in plants native to the Mediterranean Climate regions, beginning with the plants of California Floristic Province. We have often focused on California’s native plants, so we should also look closely at the plants of the four other regions.
We begin with the plants of the Mediterranean Basin. Today’s photo gallery features plants from this region, with selections from my garden’s Mediterranean bed. As described below, the large Mediterranean Basin region includes many native plants and plant communities.
With this in mind, our photo gallery represents only a sampling of this diverse region. The Mediterranean Basin includes parts of several nations: Spain, France, the Balkan States, Greece, Turkey, Syria, Lebanon, Israel, Egypt, Libya, Morocco and Algeria. It also includes about 5,000 islands in the Mediterranean Sea and several Atlantic islands: the Canaries, Madeira, the Savage Islands (Selvages), the Azores and Cape Verde.
This region has well over 13,000 plant species that are endemic, i.e., found nowhere else on Earth.
In addition to being one of the world’s five summer-dry climate regions, the Mediterranean Basin is the largest one of the world’s 36 biodiversity hotspots. The California Floristic Province, where Monterey Bay area gardeners live, is also one of the world’s biodiversity hotspots. Biodiversity hotspots are places that are biologically rich and deeply threatened by climate change and human activities, such as habitat loss, pollution, tourism and scarce water resources.
The Critical Ecosystem Partnership Fund qualifies an area as a biodiversity hotspot when it (a) contains 1,500 species of endemic vascular plants and (b) has lost at least 70% of its primary native vegetation. Biodiversity hotspots represent a small portion of the world’s landmass and include a population of 2 billion people. For a map of the world’s biodiversity hotspots: tinyurl.
com/4dkubz86 . For more about the Critical Ecosystem Partnership Fund: www.cepf.
net/our-work/biodiversity . For the fund’s focus on the California Floristic Province: tinyurl.com/39wfmjy3 .
Searching for plants native to the Mediterranean Basin or Mediterranean bioregion can be challenging. Garden centers and mail-order nurseries often label their plant offerings about exposure (sun, shade) or type (fruit tree, vine, succulent, annual, groundcover, vegetable, bulb). Plant-origin labeling is limited to California natives.
Plants from other geographic areas are not identified. Proper labeling of individual plants includes irrigation information but is unlikely to identify a plant as “summer-dry.” The easy approach is to assume that a garden center offers mostly plants compatible with the local climate and separates other plants, e.
g., orchids, in an indoor plant hothouse. A Google search for “Mediterranean plants” produces links to plants included in the five Mediterranean climate regions, but not plants specific to the Mediterranean Basin region.
An artificial intelligence search (ChatGPT.com) for “plants endemic to the Mediterranean Basin” yielded the following list of 15 garden plants (we omitted the brief descriptions and habitat notes): • Olea europaea (Olive Tree) • Quercus suber (Cork Oak) • Cistus spp. (Rockrose) • Lavandula spp.
(Lavender) • Arbutus unedo (Strawberry Tree) • Ceratonia siliqua (Carob Tree) • Pinus halepensis (Aleppo Pine) • Phlomis fruticosa (Jerusalem Sage) • Nerium oleander (Oleander) • Pistacia lentiscus (Mastic Tree) • Erica multiflora (Mediterranean Heath) • Rosmarinus officinalis (Rosemary) • Juniperus oxycedrus (Prickly Juniper) • Arum italicum (Italian Arum) • Cyclamen spp. (Cyclamen) This sample of the region’s reported 13,000 endemic species is a good first step for this plant search! The next logical step would be to narrow the search to specific countries, “plants endemic to Italy’s Mediterranean Basin region.” ChatGPT produced a list of 16 plants meeting the criteria (not yet verified).
We are not including that list in today’s column. Instead, we invite interested readers to visit ChatGPT.com to generate lists of endemic plants in any of the region’s 12 nations or five Atlantic islands listed above.
Enjoy your new gardening tool: artificial intelligence! Tom Karwin is a past president of Friends of the UC Santa Cruz Arboretum and the Monterey Bay Iris Society, a past president and Lifetime Member of the Monterey Bay Area Cactus & Succulent Society, and a Lifetime UC Master Gardener (Certified 1999-2009). He is now a board member of the Santa Cruz Hostel Society, and active with the Pacific Horticultural Society. To view photos from his garden, https://www.
facebook.com/ongardeningcom-566511763375123/ . For garden coaching info and an archive of On Gardening columns, visit ongardening.
com for earlier columns or visit www.santacruzsentinel.com/ and search for “Karwin” for more recent columns.
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