Investigations of the underground parts of medicinally used plants and possible adulterations of various Cardueae and Cichorieae

Asteraceae is the taxonomically most diverse family of plants comprising of more than 23,000 species and about 1,600 genera. Numerous representatives such as Taraxacum officinale, Cichorium intybus, Silybum marianum, and Hieracium pilosella to mention only few thereby have a long history in both traditional and western medicine. The anatomy of rhizomes and roots of a representative number of species from the tribes Cardueae and Cichorieae was analysed in detail as respective comparative studies on underground parts of medicinally used drugs and possible adulterations are missing yet for these diverse taxa. Until now, 28 genera and 37 species have been collected and examined by means of light microscopy and a database of typical anatomical characters created. In addition, some of the studied species were cultivated to follow the ontogenetic development of the underground organs at different states of growth. Particular attention was thereby spent to the secretory system: Endodermal resin ducts are characteristic to the Cardueae, whereas, according to literature data, these anatomical elements are restricted within the tribe Cichorieae to Scorzonera hispanica, Tragopogon porrifolius, and the genus Scolymus. Cichorium intybus and Lapsana communis were reported to exhibit the „doubling“ of the endodermis, but with ducts missing [1].

Based on anatomical structure, we could distinguish different types of resin ducts. These various forms of resin ducts and the structural context of their occurrence, particularly with respect to tissue of origin and their position relative to prominent anatomical elements such as vascular bundles (e.g., a centrifugal position in Centaurea scabiosa versus an interfascicular position in Carlina acaulis) provided valuable characters to discriminate among the species studied.

Reference: [1] Van Tieghem, M. Bull. Soc. Bot. Fr. 1884:112–116.