Chamomile : Yes, but which one?
There are several different species of herb known rather loosely as 'Chamomile' (or 'Camomile') but only two of the daisy-like (Compositae/Asteraceae) species have historicaly had significant uses both as medicinal herbs and as sources of essential oil. These are the perennial 'noble' chamomile Anthemis nobilis or Chamaemelum nobile which is also known as English or Roman Chamomile and the annual Matricaria recutita also known as German or Wild chamomile. There are many similar looking species with a host of local and folk names such as Mayweed or Dog-Daisy which are often incorrectly attributed to either species.
Anthemis nobilis is a perenial of creeping habit - the herb growing to a height of 30cm with flower spikes during the flowering season (July, August) to 45cm. Both the flower and upper parts of the green herb contain an essential oil which gives the plant its characteristic odour. The foliage is of a dark green sometimes almost greyish colour with a much branched 'feathery' appearence. The flowers are characterised by their flattened corolla which is easily disinguished from the dome shaped corrolla of Matricaria recutica.
Matricaria recutica, is an annual of a more erect habit growing to a height of 60cm or more and with somewhat sparser, waxy but similarly shaped feathery foliage. The fresh flowers of Matricaria when crushed, have an odour similar to, but somewhat sweeter and 'apple-like' than the more astringent Anthemis.The essential oil is only present in the flower. The extracted oils from the two species are very different: the Anthemis oil is light in density, a sky-blue colour with a clean, sweet rather floral aroma while the Matricaria oil is inky blue and somewhat viscous with a rather grassy pungent aroma that some people find unpleasant.
There are two variants of Anthemis nobilis - a double flowered variety Flora Pleno (left) traditionally used as a dried herb and a non-flowering, still aromatic, but somewhat less vigourous variety Trenague useful for the traditional 'Chamomile Lawn'.Both these varieties of Anthemis nobilis are sterile and can only be reproduced from cuttings.
Flora Pleno produces a transparent (chamazulene free) essential oil on steam distillation, somewhat similar to Anthemis nobilis proper but softer and less complex.
Finally, a mention must be made of the essential oil called 'Moroccan' Chamomile which is derived from another Compositae : Ormenis multicaulis a distant relative of Matricaria recutica. This oil has no theraputic history and is chiefly used as a perfume ingredient. The essential oil of trade is pale to brownish yellow in color with a sweet, tenacious balsamic undertone and has a high alcohol content - 'Santolina' alcohol - sometimes quoted as high as 30% but probably more like 3%. It is mostly used in perfumery to add a 'top note' in colognes etc. and only small quantites can have a strong aromatic effect. The essential oil is often erronoeusly bought by the unwary because it is generally the cheapest of the 'Chamomile' essential oils. Some experts even assert that Ormenis multicalis is not a 'true' chamomile.