RAISED STOMATAL CLUSTERS ON COLEUS (LAMIACEAE) STEMS

Stomata on stem internodes of Coleus blumei occur only in clusters on hollow epidermal bulges. We illustrate them here with light and scanning electron microsocpy. Some stomatal clusters are sites for lenticel formation on older internodes. Three Plectranthus species were also examined; two had discrete stomatal clusters while the third showed a more scattered arrangement of stomata, indicating that the stomatal pattern on stems may have some potential as a taxonomic character in Lamiaceae.