''Cneoridium'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus in the citrus family which contains the single species ''Cneoridium dumosum'', commonly known as bushrue or coast spice bush. This

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...

shrub is native to the coast of

southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most po ...

and

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

, thriving in hot, dry conditions. This plant is characterized by a distinctive citrusy aroma and small, white flowers that appear from winter to spring. The flowers eventually become round berries that resemble a miniature version of the common

citrus ''Citrus'' is a genus of flowering plant, flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as Orange (fruit), oranges, Lemon, lemons, grapefruits, pomelos, and lim ...

fruit. Widely known and utilized by the

indigenous peoples Indigenous peoples are culturally distinct ethnic groups whose members are directly descended from the earliest known inhabitants of a particular geographic region and, to some extent, maintain the language and culture of those original people ...

for centuries, this species was first discovered to Western science by

Thomas Nuttall Thomas Nuttall (5 January 1786 – 10 September 1859) was an England, English botany, botanist and zoologist who lived and worked in America from 1808 until 1841. Nuttall was born in the village of Long Preston, near Settle, North Yorkshire, S ...

, on his trip to

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...

. Today this species is listed as imperiled, with some of its habitats threatened by coastal development,

urbanization Urbanization (or urbanisation) refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. It is predominantly t ...

, military operations and

fire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts in wild land areas require different techniques, equipment, and training from the more familiar structure fire fighting found in populated a ...

. It has also found its way into

horticultural Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...

circles in the regions where it is native, providing gardeners with a low-maintenance shrub that gives off rewarding flowers. Despite attractive qualities like its distinctive fragrance and flowers, this species may cause blistering and burning rashes in people after contact with its foliage, a phenomenon common with members of the citrus family, known as phytophotodermatitis.

Description

This

, intricately branched

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

may exceed a meter and a half in height and sprawl about as wide, with a rounded form. Its twigs are covered in small, linear to oblong- shaped green

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

1 to 2.5 cm in length and arranged opposite of each other. The leaves are glabrous and are dotted with small

glands In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...

. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

is a cyme or cluster with 1 to 3 flowers. Each

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

is just over a centimeter wide with four or rarely five rounded white

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

s and eight yellow-anthered white

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...

s. The leaves of this plant are aromatic, while the flowers also give off a fragrance described as a "wonderful citrusy sweet perfume." The bunching fruits are round green

berries A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit, although many pips or seeds may be present. Common examples are strawberries, raspb ...

about half a centimeter wide covered in a thin peel which is gland-pitted like that of a common citrus fruit. In age the berries change to a reddish to brown color. Each berry contains one or two spherical seeds.

Phytochemistry

Numerous chemicals have been isolated from this plant, including osthol, imperatorin, isoimperatorin,

bergapten Bergapten (5-methoxypsoralen) is a naturally-occurring organic chemical compound produced by numerous plant species, especially from the carrot family Apiaceae and the citrus family Rutaceae. For example, bergapten has been extracted from 24 ...

, isopimpinellin, xanthotoxin,

justicidin A Justicidin A is a organic compound isolated from ''Justicia procumbens''. It is classified as a lignan. The compound may possess cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some t ...

and marmesin. This plant is also capable of causing phytophotodermatitis on humans after skin contact, and it can sometimes be severe if exposure is for several hours. After the plant's foliage is contacted, light-sensitizing chemicals in the oils of the plant combined with ultraviolet radiation initiate an inflammatory reaction that can present as a burning, blistering rash. This effect is variable from person to person, with some people not blistering at all.

Taxonomy

Taxonomic history and classification

This species was first discovered to Western science by

, an

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...

botanist and naturalist. Nuttalll had arrived in

aboard the hide ship ''Pilgrim'', staying in the harbor for three weeks as he waited for a Bryant and Sturgis ship to sail him back to

Boston Boston (), officially the City of Boston, is the state capital and most populous city of the Commonwealth of Massachusetts, as well as the cultural and financial center of the New England region of the United States. It is the 24th- mo ...

. Nuttall was one of few naturalists to step foot in the region at the time, being preceded by Menzies, Botta, Coulter, and Deppe, all of whom had only stopped in San Diego briefly. In Nuttall's stay in San Diego, he collected around 44 species of plants. Nuttall likely encountered this species on Point Loma, as he spent extensive time on the peninsula (for it was the original anchorage in the San Diego Bay) and it is home to an abundant population of this plant. From Nuttall's work, eminent North American botanists

John Torrey John Torrey (August 15, 1796 – March 10, 1873) was an American botany, botanist, chemist, and physician. Throughout much of his career, he was a teacher of chemistry, often at multiple universities, while he also pursued botanical work, focus ...

and

Asa Gray Asa Gray (November 18, 1810 – January 30, 1888) is considered the most important American botanist of the 19th century. His ''Darwiniana'' was considered an important explanation of how religion and science were not necessarily mutually excl ...

described this species as ''Pitavia dumosa'' in their ''Flora of North America''. However, the pair had failed to find Nuttall's notes on the plant, and had to

describe Shneur Hasofer is a Hasidic musician known as DeScribe. Hasofer's musical style has been characterized as "Hasidic hip-hop," "Hasidic rap" and "Hasidic R&B". Background Hasofer was born to a Chabad Hasidic family in Melbourne, Australia. Hasof ...

this species based on incomplete specimens. The botanists also noted that this species appeared to differ from the ''

Pitavia ''Pitavia'' is a genus of plant in family Rutaceae. It contains the following species (but this list may be incomplete): * ''Pitavia punctata ''Pitavia punctata'' is a species of tree endemic to Chile in the family Rutaceae. It is endemic to ...

'' genus as circumscribed by Jussieu. Botanist Joseph Dalton Hooker later combined this species into ''Cneoridium dumosum'', but he produced a ''nomen invalidum'' ( invalid name) as he failed to specify the rank. Henri Ernest Baillon later corrected Hooker's mistake in 1873, with the fourth volume of his publication ''Histoire des Plantes'', leading to the current name ''Cneoridium dumosum'' (Nutt.) Hook.f. ex Baill. The genus ''Cneoridium'' is placed in the subfamily

Amyridoideae ''Amyridoideae'' is a subfamily of the family Rutaceae. The circumscription of the family has varied considerably. A 2014 classification placed a large proportion of the genera in the family Rutaceae in Amyridoideae. A more recent 2021 classificati ...

, placing it as a close relative to '' Amyris'', its

sister clade In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

, and ''

Stauranthus ''Stauranthus'' is a genus of flowering plants belonging to the family Rutaceae The Rutaceae is a family, commonly known as the ruemorphological features, such as their fleshy fruits, characterized in this genus by the berries.

Etymology

The generic name ''Cneoridium'' derives from the diminutive form of ''

Cneorum ''Cneorum'' is a genus of flowering plants in the rue or citrus family Rutaceae. The two species are native to Europe and the Canary Islands. Species , Plants of the World Online accepted the following two species: *'' Cneorum pulverulentum'' Ven ...

'', the spurge olive, which in turn comes from the Greek ''kneoron'', which was applied to some dwarf shrubs resembling the olive. The first letter of ''Cneoridium'' is silent, with the name pronounced like "Nee-oh-rí-di-um." The specific epithet ''dumosum'' is derived from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''dūmōsus'', which means bushy or shrubby. The common name "spice bush" likely refers to the shrub's aromatic leaves.

Distribution and habitat

This species is distributed within the states of

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

and

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. In California, this species occurs on the southern coast in

and Orange counties, and on

San Clemente Island San Clemente Island (Tongva: ''Kinkipar''; Spanish: ''Isla de San Clemente'') is the southernmost of the Channel Islands of California. It is owned and operated by the United States Navy, and is a part of Los Angeles County. It is administered b ...

. In Baja California, this species is found throughout the northwestern portion of the state south to the

Central Desert The deserts of Australia or the Australian deserts cover about , or 18% of the Australian mainland, but about 35% of the Australian continent receives so little rain, it is practically desert. Collectively known as the Great Australian desert, th ...

. It also has a disjunct distribution in the Sierra de San Borja near Bahia de Los Angeles in southern Baja California. Plants of this species primarily occur on bluffs, mesa, hillsides and washes near the coast, and the slightly inland foothills of the

Peninsular Ranges The Peninsular Ranges (also called the Lower California province) are a group of mountain ranges that stretch from Southern California to the southern tip of the Baja California peninsula; they are part of the North American Coast Ranges, which ...

. It is found in

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...

coastal sage scrub Coastal sage scrub, also known as coastal scrub, CSS, or soft chaparral, is a low scrubland plant community of the California coastal sage and chaparral subecoregion, found in coastal California and northwestern coastal Baja California. It is w ...

and coastal succulent scrub habitats below 1000 meters. This plant is considered to play an important role in the habitat for the San Quintin Quail ( Callipepla californica subsp. plumbea).

Uses

Cultivation

Introduced into cultivation by

Theodore Payne Theodore Payne (June 19, 1872 - May 6, 1963), was an English horticulturist, gardener, landscape designer, and botanist. His best known work was done over his adult life in Southern California. Biography Payne was born at Manor Farm, Church Brampt ...

, this diminutive woody shrub has a reputation of being difficult to establish, but given proper care it is a long-lived, slow-growing plant that thrives on neglect. Native to a large number of habitats, from the moist coast to the dry inland hills, it is adaptable to

irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...

. It tolerates hot, dry climates with some afternoon shade, often staying green with no water after establishment. It may be watered sparingly during the hot season to help keep the leaves more vibrantly green. It is also recommended to keep plants away from pathways because of the risk of phytophotodermatitis triggered by the foliage. Although more commonly grown by nurseries for habitat restoration, bushrue can be utilized in local native gardens, with their moderate size compatible with small gardens. It often goes dormant in summer, with the leaves becoming dull green, and in the fall or winter they may turn yellow or orange with frost. This plant will frequently bloom in winter to spring, with rewarding January flowers. This plant can be propagated by cuttings or

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

. Cuttings must be taken in winter or spring from stems at least 1 year old, and treated with rooting hormone after the foliage is removed from the bottom half of the cutting. Cuttings are then placed in a mix of half

peat Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...

and half moist perlite, watered, and situated in a plastic bag that is not entirely sealed. The plastic bag is then placed in a warm spot with indirect sunlight. To propagate from seed, berries must be picked when they are a distinctive chocolate-brown color at the end of summer. Seed germination rates can approach 100% when they are also

stratified Stratification may refer to: Mathematics * Stratification (mathematics), any consistent assignment of numbers to predicate symbols * Data stratification in statistics Earth sciences * Stable and unstable stratification * Stratification, or st ...

at 55 °F for a couple of weeks.

Ethnobotany

This species was utilized for medicinal purposes by the indigenous Luiseño and

Kumeyaay The Kumeyaay, also known as Tipai-Ipai or by their historical Spanish name Diegueño, is a tribe of Indigenous peoples of the Americas who live at the northern border of Baja California in Mexico and the southern border of California in the Unit ...

peoples for centuries. The Luiseño would make an infusion by boiling the leaves of this plant, noting that it had a blood-thinning effect that included diuretic action. They would also use it to cure earaches, by placing the raw leaves in the ear with a small amount of warm olive oil.

Delfina Cuero Delfina Cuero (ca 1900 – 1972) was a Native American writer of the Kumeyaay people. The daughter of Vincente Cuero and Cidilda Quaha, she was born in Xamca (later known as Jamacha). The Kumeyaay people, whose traditional lands straddle the M ...

of the Kumeyaay people reported using the boiled plant as a mouthwash and gargle, and also for toothaches.

Gallery

File:Cneoridium dumosum 59668373.jpg, Flowering in habitat File:Cneoridium dumosum 120150255.jpg, Flowers with berries File:Cneoridium dumosum 73339797.jpg, The unripe red and green berries File:C. dumosum 2.jpg, Flowers with foliage File:Cneoridium dumosum 139607075.jpg, The berries, after turning brown in the summer sun

References

External links

Jepson Manual Treatment - ''Cneoridium dumosum''

USDA Plants Profile

Cneoridium dumosum - Photo gallery
{{Taxonbar, from1=Q15930442, from2=Q5137348 Flora of California Flora of Baja California Rutaceae Monotypic Rutaceae genera Taxa named by Henri Ernest Baillon Taxa named by William Jackson Hooker Taxa named by Thomas Nuttall Plants used in traditional Native American medicine