The smell of freshly cut grass is an odour caused by green leaf volatiles (GLVs) released when it is damaged. Mechanical damage to grass from activities such as lawnmowing results in the release of cis-3-hexenal and other compounds that contribute to a grassy or "green" smell. cis-3-Hexenal has a low odour detection threshold that humans can perceive at concentrations as low as 0.25 parts per billion.
The GLVs responsible for the smell of freshly cut grass play a role in plant communication and plant defence against herbivory, functioning as a distress signal warning other plants of imminent danger and, in some instances, as a way to attract predators of grass-eating insects. For humans, the smell of freshly cut grass is connected through olfactory memory to past experiences involving the odour and may evoke nostalgia, eliciting associations with spring or summer.
When grass is cut or damaged, lipoxygenase enzymes begin a breakdown of membranes in the plant's cells, producing linoleic and linolenic acids. Exposure to oxygen leads to the formation of cis-3-hexenal, which rapidly breaks down to cis-3-hexenol (leaf alcohol) and (E)-2-hexenal (leaf aldehyde). These green leaf volatiles (GLVs) are a combination of alcohols, aldehydes, and esters. The oxygenated hydrocarbons cause a "green" odour. [1]
The main compound responsible for the smell of freshly cut grass is cis-3-hexenal. It has a low odour detection threshold that humans can perceive at concentrations as low as 0.25 parts per billion. The compound is highly unstable and breaks down into (E)-2-hexenal (leaf aldehyde), [2] which may account for why the smell is said to fade rapidly. [3]
The composition of green leaf volatiles produced by cut grasses varies. In lawns, hayfields, and meadows, other plant species such as clover may be present. Sweet clover may impart a haylike or vanilla-like scent due to the presence of coumarin. [4]
While grasses release hydrocarbons passively and in response to strong sunlight, when cut or damaged, the emissions may increase by a factor of 180. [5] A second release of volatile organic compounds occurs after grass has been cut. An experiment analysing cut red fescue grass ( Festuca rubra ) and white clover ( Trifolium repens ) found prolonged releases of (Z)-3-hexenal, (Z)-3-hexenol, and hexenyl acetate. The emissions also included acetaldehyde, acetone, butanone, methanol, and possibly formaldehyde. [6] Highly reactive hydrocarbons released by cut grass combine with gases such as nitrogen oxides and exacerbate photochemical smog and urban air pollution by contributing to the formation of aerosols and ozone. [7] [8] In cities, lawnmowing can account for 10% of the total hydrocarbon release into the atmosphere. [5]
Green leaf volatiles (GLVs) are volatile organic compounds that play an important role in plant communication and plant defence against herbivory. The release of GLVs functions as a distress signal to other plants that danger is imminent. GLVs may also attract the predators of grass-eating insects, with insect and bird species having been shown to respond to GLV releases by certain injured plants. [9] [10]
For humans, the smell of freshly cut grass is connected through olfactory memory [11] to experiences related to lawns, lawn mowers, [12] or haying. The smell may evoke nostalgia, eliciting associations with spring or summer, [13] parklands, golf courses, or preparations for sporting events. [14] [15]
The smell of freshly cut grass is described as a leafy or "green" scent. [1] [16] Positive associations to GLVs released by grasses may be due to their similarity to the GLVs released by edible plants such as vegetables when they are ripe. [17]
The smell of freshly cut grass has been described as "uplifting", [18] and behavioral studies have shown that the smell has a "healing effect on psychological damage caused by stress". [16] Hexanal, which resembles the smell of freshly cut grass, can increase interpersonal trust. [19]
A trademark case before the Office for Harmonization in the Internal Market addressed an attempt to secure a trademark for the smell of freshly cut grass for use with tennis balls. An appeals board found that "the smell of freshly cut grass is a distinct smell which everyone immediately recognizes from experience. For many, the scent or fragrance of freshly cut grass reminds them of spring or summer, manicured lawns or playing fields, or other such pleasant experiences." [20]
Happiness in childhood may have a bearing on the subjective experience of the smell. In one study, people born before 1960 recalled a happy childhood when describing the smell of freshly cut grass, while those born after 1960 described unhappy childhoods. Subjects born earlier had pride in the responsibility of cutting grass while those born later associated the smell with chores. [21]
About 12% of humans have difficulty smelling cis-3-hexen-1-ol. [22] A pair of single-nucleotide polymorphisms in the OR2J3 gene strongly reduce sensitivity to the odorant cis-3-hexen-1-ol, which has a "cut grass" smell. [23]
The toxic, colourless gas phosgene smells like freshly cut grass. [24] The Mauzac-based sparkling wine Blanquette de Limoux has aromas of fresh cut grass. [25]
The chemicals responsible for the smell of freshly cut grass are used as aroma compounds by the perfume industry. Hexanal and related compounds are used by the food industry in recreating fruit and vegetable flavours. The yearly production of cis-3-Hexen-1-ol is about 30 tonnes. The compound, which has the smell of freshly cut grass, is naturally present in tomatoes, kiwifruit, olive oil, and green tea. [26]
Asparagus is a perennial flowering plant species in the genus Asparagus native to Eurasia. Widely cultivated as a vegetable crop, Its young shoots are used as a spring vegetable.
Companion planting in gardening and agriculture is the planting of different crops in proximity for any of a number of different reasons, including weed suppression, pest control, pollination, providing habitat for beneficial insects, maximizing use of space, and to otherwise increase crop productivity. Companion planting is a form of polyculture.
Isoprene, or 2-methyl-1,3-butadiene, is a common volatile organic compound with the formula CH2=C(CH3)−CH=CH2. In its pure form it is a colorless volatile liquid. It is produced by many plants and animals (including humans) and its polymers are the main component of natural rubber. C. G. Williams named the compound in 1860 after obtaining it from the pyrolysis of natural rubber; he correctly deduced the empirical formula C5H8.
1-Hexanol (IUPAC name hexan-1-ol) is an organic alcohol with a six-carbon chain and a condensed structural formula of CH3(CH2)5OH. This colorless liquid is slightly soluble in water, but miscible with diethyl ether and ethanol. Two additional straight chain isomers of 1-hexanol, 2-hexanol and 3-hexanol, exist, both of which differing by the location of the hydroxyl group. Many isomeric alcohols have the formula C6H13OH. It is used in the perfume industry.
Fodder, also called provender, is any agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food given to the animals, rather than that which they forage for themselves. Fodder includes hay, straw, silage, compressed and pelleted feeds, oils and mixed rations, and sprouted grains and legumes. Most animal feed is from plants, but some manufacturers add ingredients to processed feeds that are of animal origin.
An aroma compound, also known as an odorant, aroma, fragrance or flavoring, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently volatile for transmission via the air to the olfactory system in the upper part of the nose. As examples, various fragrant fruits have diverse aroma compounds, particularly strawberries which are commercially cultivated to have appealing aromas, and contain several hundred aroma compounds.
cis-3-Hexen-1-ol, also known as (Z)-3-hexen-1-ol and leaf alcohol, is a colorless oily liquid with an intense grassy-green odor of freshly cut green grass and leaves. It is produced in small amounts by most plants and it acts as an attractant to many predatory insects. cis-3-Hexen-1-ol is a very important aroma compound that is used in fruit and vegetable flavors and in perfumes. The yearly production is about 30 tonnes.
Petrichor is the earthy scent produced when rain falls on dry soil. The word is constructed from Ancient Greek πέτρα (pétra) 'rock', or πέτρος (pétros) 'stone', and ἰχώρ (ikhṓr), the ethereal fluid that is the blood of the gods in Greek mythology.
cis-3-Hexenal, also known as (Z)-3-hexenal and leaf aldehyde, is an organic compound with the formula CH3CH2CH=CHCH2CHO. It is classified as an unsaturated aldehyde. It is a colorless liquid and an aroma compound with an intense odor of freshly cut grass and leaves.
Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula (CH3)2S. The simplest thioether, it is a flammable liquid that boils at 37 °C (99 °F) and has a characteristic disagreeable odor. It is a component of the smell produced from cooking of certain vegetables, notably maize, cabbage, beetroot, and seafoods. It is also an indication of bacterial contamination in malt production and brewing. It is a breakdown product of dimethylsulfoniopropionate (DMSP), and is also produced by the bacterial metabolism of methanethiol.
Vachellia cornigera, commonly known as bullhorn acacia, is a swollen-thorn tree and Myrmecophyte native to Mexico and Central America. The common name of "bullhorn" refers to the enlarged, hollowed-out, swollen thorns that occur in pairs at the base of leaves, and resemble the horns of a steer. In Yucatán it is called "subín", in Panamá the locals call them "cachito". The trees are commonly found in wet lowlands
Coffee cupping, or coffee tasting, is the practice of observing the tastes and aromas of brewed coffee. It is a professional practice but can be done informally by anyone or by professionals known as "Q Graders". A standard coffee cupping procedure involves deeply sniffing the coffee, then slurping the coffee from a spoon so it is aerated and spread across the tongue. The coffee taster attempts to measure aspects of the coffee's taste, specifically the body, sweetness, acidity, flavour, and aftertaste. Since coffee beans embody telltale flavours from the region where they were grown, cuppers may attempt to identify the coffee's origin.
Hexanal, also called hexanaldehyde or caproaldehyde is an alkyl aldehyde used in the flavor industry to produce fruity flavors. Its scent resembles freshly cut grass, like cis-3-hexenal. It is potentially useful as a natural extract that prevents fruit spoilage. It occurs naturally, and contributes to a hay-like "off-note" flavor in green peas.
Olfactory receptor 2J3 is a protein that in humans is encoded by the OR2J3 gene.
An odor or odour is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and many animals can perceive via their sense of smell. An odor is also called a "smell" or a "scent", which can refer to either an unpleasant or a pleasant odor.
The sense of smell, or olfaction, is the special sense through which smells are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste.
Nicotiana attenuata is a species of wild tobacco known by the common name coyote tobacco. It is native to western North America from British Columbia to Texas and northern Mexico, where it grows in many types of habitat. It is a glandular and sparsely hairy annual herb exceeding a meter in maximum height. The leaf blades may be 10 centimetres (4 in) long, the lower ones oval and the upper narrower in shape, and are borne on petioles. The inflorescence bears several flowers with pinkish or greenish white tubular throats 2 to 3 centimetres long, their bases enclosed in pointed sepals. The flower face has five mostly white lobes. The fruit is a capsule about 1 centimetre long.
Green leaf volatiles (GLV) are organic compounds released by plants. Some of these chemicals function as signaling compounds between either plants of the same species, of other species, or even different lifeforms like insects.
Mertensia maritima is a species of flowering plant in the borage family, and is known by the common names oyster leaf in North America, oyster plant in the British Isles, and sea bluebells.
Floral scent, or flower scent, is composed of all the volatile organic compounds (VOCs), or aroma compounds, emitted by floral tissue. Other names for floral scent include, aroma, fragrance, floral odour or perfume. Flower scent of most flowering plant species encompasses a diversity of VOCs, sometimes up to several hundred different compounds. The primary functions of floral scent are to deter herbivores and especially folivorous insects, and to attract pollinators. Floral scent is one of the most important communication channels mediating plant-pollinator interactions, along with visual cues.