Analysis of leaves trichomes of Eclipta prostrata, Eleutheranthera ruderalis, Synedrella nodiflora, and Tridax procumbens (Asteraceae, Heliantheae)

Asteraceae is a family of flowering plants distributed widely in the terrestrial regions. Asteraceae are grouped into several tribes. Species of the Heliantheae tribe including Eclipta prostrata, Eleutheranthera ruderalis, Synedrella nodiflora, and Tridax procumbens are the most commonly found at Universitas Indonesia Campus, Depok. The research was conducted to describe the morphology and the density of leaves trichomes as a species identification character and for classification purpose that has taxonomic value within several species of tribe Heliantheae. The digital images of leaves were captured using a Dino-Lite digital microscope device and Dino capture 2.0 application to measure the area of leaves and the number of trichomes. The number of trichomes was calculated using ImageJ software. The light microscope was used to observe the trichome morphology. The results showed that trichomes density in young leaves was higher than in the old leaves. Eclipta prostrata, Eleutheranthera ruderalis, and Synedrella nodiflora showed micromorphology of trichome with ornamentation on the surface of the trichome, while Tridax procumbens not. The numbers of leaves trichomes per unit area were also different between species of Heliantheae tribe. Eclipta prostrata has the lowest number of trichomes density with a range of trichomes from 1.15/mm2 to 6.375/mm2 on the surface of young leaves and old leaves. Synedrella nodiflora has the highest trichomes density with a range of trichomes from 2.68/mm2 to 15.71/mm2. The four members of the Heliantheae tribe have a higher density of leaves trichomes on the lower surface (abaxial) than the upper surface (adaxial) of the leaves.