Cneoridium

It is not recommended to touch this plant, as it may cause phytophotodermatitis.

Numerous chemicals have been isolated from this plant, including osthol, imperatorin, isoimperatorin, bergapten, isopimpinellin, xanthotoxin, justicidin A and marmesin.[8] 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.[9] 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.[3] This effect is variable from person to person, with some people not blistering at all.[10]

This species was first discovered to Western science by Thomas Nuttall, an English botanist and naturalist. Nuttall had arrived in San Diego 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. Nuttall was one of few naturalists to set 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.[11] 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)[12] and it is home to an abundant population of this plant.[13]

From Nuttall's work, eminent North American botanists John Torrey and Asa Gray 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 this species based on incomplete specimens. The botanists also noted that this species appeared to differ from the Pitavia genus as circumscribed by Jussieu.[14] Botanist Joseph Dalton Hooker later combined this species into Cneoridium dumosum,[15] but he produced a nomen invalidum (invalid name) as he failed to specify the rank.[16] 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.[17]

The genus Cneoridium is placed in the subfamily Amyridoideae, placing it as a close relative to Amyris, its sister clade, and Stauranthus. The three genera also share morphological features, such as their fleshy fruits, characterized in this genus by the berries.[18]

The generic name Cneoridium derives from the diminutive form of Cneorum, the spurge olive, which in turn comes from the Greek kneoron,[19] which was applied to some dwarf shrubs resembling the olive.[20][21] The first letter of Cneoridium is silent, with the name pronounced like "Nee-oh-rí-di-um."[22] The specific epithet dumosum is derived from the Latin dūmōsus, which means bushy or shrubby.[23] The common name "spice bush" likely refers to the shrub's aromatic leaves.[7]

Introduced into cultivation by Theodore Payne,[13] 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.[27] Native to a large number of habitats, from the moist coast to the dry inland hills, it is adaptable to irrigation. 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.[10]

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.[10] This plant will frequently bloom in winter to spring, with rewarding January flowers.[5]

This plant can be propagated by cuttings or seed. 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 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.[28] 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 at 55 °F for a couple of weeks.[29]

This species was utilized for medicinal purposes by the indigenous Luiseño and Kumeyaay 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.[30] They would also use it to cure earaches, by placing the raw leaves in the ear with a small amount of warm olive oil.[31] Delfina Cuero of the Kumeyaay people reported using the boiled plant as a mouthwash and gargle, and also for toothaches.[32]