|Description of Trichomes:
Peltate glandular secreting trichomes (GST).
The large peltate glandular trichomes are the most important trichome type. These trichomes consist of a base cell, stalk cell, and a 4 celled head (Werker et al. Annals of Bot 71:43-50). The four cells form a disc and essential oils and other compounds into an elevated head space covered by a waxy cuticle. The major secondary metabolites that accumulate are basil line specific. For example, the SW line accumulates large amounts of the phenylpropanoid eugenol and the monoterpanoid linalool, while these volatiles are not found in the MC line where the phenylpropanoid mehylcinnanmate is dominant (Xie et al., Plant J 54:349).
Basil leaves also exhibit a smaller capitate glandular trichome consisting of a single base and stock cell and one to two celled head. Multicellular non-glandular spiked trichomes are often found on the mid vein.
1) Werker E, Putievsky E, Ravid U, Dudai N. and Katzir I. (1993) Glandular Hairs and Essential Oil in Developing Leaves of Ocimum basilicum L. (Lamiaceae). Annals of Botany 71: 43-50.
2) Xie Z, Kapteyn J, Gang DR. (2008) A systems biology investigation of the MEP/terpenoid and shikimate/phenylpropanoid pathways points to multiple levels of metabolic control in sweet basil glandular trichomes. Plant J. 54:349-361.