Mould
The microbial flora of mould depends on the biotope and the type of plant material being degraded, but certain odour notes are general and may be ascribed to specific secondary metabolites of the detritus organisms. The following examples are typical:
2-Methylisoborneol has a strong camphoraceous odour, sometimes also recognizable from ponds and lakes. You react reflexively if you get food into your mouth having traces of this flavour - "it is mouldy"! 2-Methylisoborneol is a metabolite of Streptomyces spp., Penicillium spp. and Actinomyces spp. and has a very low olfactory detection threshold.
Geosmin has an odour known from moist cellars, and is also an aroma component of beetroot. It is a metabolite of Streptomyces spp. Actinomyces spp. and blue-green algae.
2-Isopropyl-3-methoxypyrazine is another odour note from mould, reminiscent of the odour of potato peel and green bell-pepper. It is a metabolite of Penicillium spp., Pseudomonas spp. and Streptomyces spp. [73].
1-Octene-3-ol is present in a multitude of mushrooms whose mycelium permeates the soil. It is the most important aroma component in fresh champignons [6].
P.S. Some cactus flowers, e.g. those of Rebutia marsoneri (Cactaceae), shown on the right, give off dehydrogeosmin [5]. Presumably they are pollinated by insects attracted by the smell of moisture.

Musk
Moschus moschiferus (Moschidae), Musk deer
The small musk deer is living in valleys of high altitude in the Himalayas and the so-called Tonkin Triangle. It is an unusual animal in a number of ways. The males, for instance, haven't got antlers, instead they carry an impressive pair of eye teeth in their upper jaw. Musk is the fatty excretion produced by the males during the mating season in order to attract females. The dried musk glands from killed animals have been sold at high prices for thousands of years as one of perfumery's most precious materials. Two of these 'musk pods' are shown in the photo on the right.
Today the musk deer is protected by conservational laws. Besides, muscone, the major odorant from musk, can now be made by organic synthesis.
Natural muscone is (-)-(R)-3-methylcyclopentadecanone. It is found together with small amounts of muscopyridine, supplying an urinaceous undertone [3].
In several species of mammals the males use musks as pheromones. Other examples are the civet and the musk rat. The musk compounds may be macrocyclic ketones as well as lactones. Musk lactones are also found in some plants (see ambrette seeds and angelica). Both types have a deep, soft, musky character, but the ketones have the most penetrating and animalic odour.

about new artificial musk odorants
Extensive research in the chemistry of musks for more than a century has made a whole palette of macrocyclic musks available, some of them showing new twists to the musk character. A few examples:
Velvione ® has a beautiful nitro-musk character (the nitro-musks were the first artificial musks to be discovered; they had desirable olfactory properties but are now largely banned for toxicological reasons). It is said that the perfume Velviona (Helmut Lang 2001, limited release) contained Velvione ® as the only ingredient!
Cosmone ®, newly released from Givaudan and the first C14-macrocyclic musk commercially available, also has a nitro-musk character of great warmth and diffusion. It plays an important role in the perfume Pi Neo (Givenchy 2008).
Musk R1 ® (originally from Quest International) is an example of an oxa-macrolide. It has a sensual, powdery musk character.
These musks are available from, e.g., The Perfumer's Apprentice.
Macrocyclic musks are expensive odorants. Continued research therefore aims at discovering new members with lower olfactory threshold values (OTVs). It has been demonstrated that even thia-macrolides may have a pleasant musk character.
7-Thia-pentadecanolide, for example, was shown to have an intense, linear musk odor accompanied by green-mossy aspects and an OTV as low as 0.2 ng/l air [199].
Even non-macrocyclic compounds may show a musky character. Helvetolide ®, discovered by the Swiss company Firmenich in 1990, has a sophisticated, modern musky note with a fruity pear aspect.
Etymology: Velvione, from velvet and ketone, hinting at the velvety softness of the odor of this macrocyclic ketone. Cosmone, following a tradition of grandiose naming of synthetic musks, also alludes to the cosmetic appeal of this compound. Helvetolide, lat. Helvetia for Switzerland.

Musk rat
Ondatra zibethicus (Muridae), Bisam
The musk rat is a native of North America. In 1905 three couples were brought to Bohemia for the sake of the fur, some of their offspring escaped, and soon the musk rat spread to most of Central Europe. I Denmark, the musk rat has inhabited southern Jutland since the late 1990s.
The musk rat is a large semi-aquatic rodent. The eyes and ears are small, and the hind feet are partially webbed. The tail is long, sparsely haired, and laterally compressed. Musk rats live in freshwater and saltwater marshes, swamps, and along the borders of ponds, lakes, and streams.
Musk rats possess a pair of musk glands which enlarge during the breeding season, especially in males. These glands emit a yellowish secretion with a strong musky odor. The odoriferous principles are some eleven macrocyclic ketones with cyclopentadecanone (21 %) as one of the major constituents [3].
In 1925 the Swiss company Firmenich started a production of cyclopentadecanone for perfumery use (Exaltone ®),
based on the work on macrocyclic musks by Leopold Ruzicka (shown in the laboratory on the photo in the middle). Ruzicka earned the Nobel Prize in chemistry in 1939.
Pure cyclopentadecanone is a crystalline substance with mp. 63°C (photo). It has a powerful and clean musk odor, very similar to that of muscone, and, in the opinion of many perfumers, superior in type and beauty. It ranks among the finest and most effective fixatives known, and it improves the 'wearability' of a perfume when properly incorporated in the fragrance. Its power becomes more perceptible and evident in extreme dilution, e.g. below one percent in the perfume oil - according to Arctander (see referenced literature).
Etymology: Lat. zibethicus, from Lat. zibetha, the name of the musky smelling civet cat.

Narcissus
Narcissus poeticus (Amaryllidaceae) Poet's narcissus
Narcissus tazetta (Amaryllidaceae) Tazette
Narcissus jonquilla (Amaryllidaceae) Jonquil
The genus Narcissus includes around 25 species from the Mediterranean countries, Central Europe and western Asia. They are recognised, for example, by their bell-shaped corona.
N. poeticus, the narcissus praised by Homer, grows in sub-alpine meadows from Spain to Yugoslavia with the southern Alps as its northern border. Its corona has a crisp red margin (the first two photos). N. tazetta, with several smaller flowers on its shaft, is common in the Israeli mountains for example (the next two photos, taken in the Judean hills west of Jerusalem). N. jonquilla has slender leaves and 2-6 brightly yellow flowers on its shaft. It grows naturally in the western Mediterranean countries (last photo).
The odor of narcissus flowers has always fascinated perfumers - an elegant and rich floral odor with a smooth animal undertone. There are lots of cultivars, most of them are less fragrant, and for unknown reasons even some with ugly filled flowers have been developed!
A number of well-known essential oil components like benzyl acetate, methyl benzoate, p-cresol, phenethyl alcohol and indole are common to many narcissus varieties, but none of these odorants are specific for narcissus.
Van Dort et al. analysed the extract of two fragrant varieties (N. trevithian and N. geranium) derived from the above species and found several new compounds. Some of these (from N. trevithian) were synthesised in order to determine their odor, for example 8-oxolinalool, 3,7-dimethyl-1,3,5-octatriene-7-ol, methyl 2-methyl-6-methylene-2,7-octadienoate, 8-hydroxylinalool, 2-methoxy-2,6-dimethyl-3,5,7-octatriene and lilac aldehyde - as shown above. However, no character impact compounds were identified [189].
Etymology: Gr. narcosis, because of the 'narcotic' fragrance of the flowers, or, Gr. Narcissos, a beautiful young man of Greek mythology. It. tazzetta, small cup, because of the cup-shaped, yellow corona of the flower. Sp. junquillo, 'little rush', i.e. rush-leaved.

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