Osculating Relations

CoCo Tin

In English, Interstitial is defined as ‘of, forming, or occupying interstices.’ Its ecological definition speaks to (minute animals) living in the spaces between individual sand grains in the soil or aquatic sediments.

In Chinese, “間隙” translates more directly –and spatially– as a gap, an interval, or a break. Moreover, in reference to geology, 間隙 relates to diastem, a short interruption in sedimentation with little or no erosion, or can also be described as very short unconformities.

Inspiring the above (mis)translations, slippages, and overlapping registrations between English and Chinese languages/cultures is the flourishing Ailanthus altissima. While colloquially known as the Tree of Heaven, a resilient weed species commonly found in the United States, their other names, medicinal applications, and osculating relations are what I hope to tease out as a companion to Che Yeh’s exhibition, Interstitial Lives.

Devilish Invader or sought-after guest?

Ailanthus altissima, on the venerable Nature Conservancy website, is described as a fast-growing weed, a non-native species reaching for the sky. Together, their resiliency and unpleasant odour (when crushed), is decisively labeled an invasive species, a devilish invader. (A leafy incoming attacker!) But how exactly did this invader come to the United States?

Early official records show Ailanthus’s travel from Peking to Paris in the 1740s, a transcontinental trip via Siberia accompanied by Pierre d’Incarville. The plant arrived in America via England, some 40 years later in 1784. William Hamilton of Philadelphia was the first to introduce this Tree of Heaven into his private garden. By the 1820s, demand for this small tree in the public realm appeared for their aesthetic and utility: Ailanthus was able to thrive in the poorest of soils and immune to the dirt and smoke of cities. Prince and Parsons Nurseries of Flushing, Long Island, New York, handled their distribution, planting them in New York, Brooklyn, Baltimore, and Boston. This short but crucial piece of history begs us to wonder: Was the Tree of Heaven an unwelcomed, devilish invader or a sought-after guest, groomed as a spatial remedy to beautify industrial American cities?

But perhaps most interesting to me is Ailanthus’s arrival in the US as a medicinal cure. In the 1850s, literature cites that Chinese immigrants may have carried their seeds as medicinal plants with them to California, used as an astringent, antispasmodic, and anthelmintic.

Dating much earlier to 731 AD, in China, the first recorded use of Ailanthus root was for mental illness; the bark of the root (best) or stem, preferably collected in the Spring, was, and is still, used in combination with various other plants and herbs in therapeutic concoctions. In 684 AD, other literature points to the use of leaves for their slightly poisonous quality. When taken internally, they affect the nervous system, making unsettled minds sleepy, slowing of breath, and weakening of the pulse. For external use, Ailanthus leaves can also be boiled in water to make a wash to cure skin ailments such as boils and even baldness. In Traditional Chinese medicine, Ailanthus's bark, root, stem, and leaves, are associated with cooling properties, eliminating ‘damp heat.’ Thus, the Tree of Heaven cannot be conformed to the binaries of a poison or a remedy. They occupy the interstitial space of both, replenishing human life by temporarily spoiling it.

Natural Herbicide: quassinoids and the compound ailanthone

While the Tree of Heaven’s medicinal applications are somewhat known in the US, their qualities as a natural (insect) repellent are much less documented. An article from 1997 published by the Arnold Arboretum of Harvard University, titled, ‘Allelopathy and the Secret Life of Ailanthus altissima,’ elaborates on the potential for the species as a source of natural herbicide.

The Tree of Heaven produces a class of bitter-tasting secondary metabolites, organic compounds that are not directly involved in the normal growth, development, or reproduction of the organism. These quassinoids contain the phytotoxic compound ailanthone, found in high effects in the inner bark of the trunk, the bark of roots, and branches. The article illustrates the author/botanist’s laboratory experimentation with ailanthone as a natural herbicidal compound, meaning an ability to reduce (pre-emergence) and temporarily injure ‘invasive’ crops (post-emergence) without long-term soil degradation. This begs us to wonder, what about alianthone’s toxicity concerning itself, the Tree of Heaven? Interestingly, some evidence suggests that the toxicity is a function to protect against fungal pathogens and a deterrent to herbivores for its extremely bitter taste. While more studies are needed for large-scale applications of Ailanthus as a natural herbicide, the results are promising.

In the spatial, medical, and even molecular realm, the Tree of Heaven is perhaps what Algerian-French philosopher Jacques Derrida would describe as pharmakon—a remedy and a poison, both good and evil, and a dilemma of the interior and the exterior. Cross-species kinship is an entanglement of many relations and scales, from cities to bodies, trees to compounds. Simultaneously, amidst and beyond the interstices of Boston’s Chinatown neighbourhood of buildings, highways, and fences, Ailanthus altissima pollinates across time and cultures, not only penetrating neoliberal urbanization– but the foundational understanding of what it means to be a devilish invader or welcomed guest, remedy or poison, herb or herbicide—forever osculating in, however long or short, relations.

CoCo Chi Ting Tin【田智婷】is an architectural designer and writer from Hong Kong, currently rooted in New York City.