ABSTRACT

Two of the plants are known as chamomile. The first consists of the flower heads of Matricaria recutita L., also referred to as Chamomilla recutita (L.) Rauschert or Matricaria chamomilla L.p.p. These three scientific names, all referring to the same plant, simply reflect taxonomic confusion. Commonly, the herb is known as German or Hungarian chamomile. The second chamomile consists of the flowerheads of Chamaemelum nobile (L.) All., also known, especially in the older literature, as Anthemis nobilis L. Its common names are Roman or English chamomile. The third plant in this general category consists of the flowering herb (entire overground plant) of Achillea millefolium L., commonly known as yarrow or milfoil. More recent taxonomic and phytochemical understanding of the A. millefolium group reveals that the widespread A. millefolium sensu stricto, abundant in Europe, is a hexaploid, while North American material once thought to be naturalized A. millefolium from Europe is a separate tetraploid taxon, now designated A. lanulosa Nutt. Chemical differences are associated with these genetic variations. The essential oil of hexaploid A. millefolium is azulene-free, while the essential oil of the tetraploid North American A. lanulosa, and of the European A. collina Becker, contains azulene and chamazulene. This knowledge can help explain why anti-inflammatory activity could not be associated with A. millefolium from Eastern Europe in a number of pharmacological assays. Variation in azulene

content has also been associated with soil type, with high amounts of proazulenes associated with yarrow growing conditions, correlat­ ing high levels of azulenes to soils with increased concentrations of available phosphate, magnesium, and manganese. Proazulene-free diploids and hexaploids are associated with nutrient-poor, acid, dry sites.2