Plant defense against herbivory which differ from one another in both functional groups, and in basic carbon skeletons. Monoterpenoids, continuing 2 isoprene units, are volatile essential oils such as citronella, limonene, menthol, camphor, and pinene. Diterpenoids, 4 isoprene units, are widely distributed in latex and resins, and can be quite toxic. Diterpenes are responsible for making "Rhododendron" leaves poisonous. Plant steroids and sterols are also produced from terpenoid precursors, including vitamin D, glycosides (such as digitalis) and saponins (which lyse red blood cells of herbivores). Phenolics, sometimes called "phenols", consist of an aromatic 6-carbon ring bonded to a hydroxy group. Some phenols have antiseptic
Orazio Comes Orazio Comes Orazio Comes (11 November 1848 – 13 October 1917) was an Italian botanist. From 1906 to 1917 he directed the Agricultural Higher Institute of Portici, in which, thanks to Vincenzo de Cesati, he begun teaching since 1877 as assistant of Nicola Pedicino for the chair of botany, to whom he succeeded in 1880. In his works he studied the physiology and plant pathology of Neapolitan mushrooms and agricultural plants, such as beans and tobacco. From 1881, Comes began to deal with the cultivation of tobacco to improve industrial production and, starting from 1891, he emphasized the study and