**Chemical Composition of Epicuticular Wax and Farina:**
– Epicuticular wax composition includes aliphatic hydrocarbons, fatty acids, primary alcohols, aldehydes, and triterpenes.
– Different plant species exhibit varying wax compositions like paraffins in peas and alkyl esters in carnauba palm.
– Farina, found in species like Primula and ferns, consists of polyphenolic compounds and is not wax.
– Farina is secreted by glandular hairs and is whitish to pale-yellow in color.
**Physical Properties and Effects of Epicuticular Wax:**
– Epicuticular waxes are solid at ambient temperatures with melting points above 40°C and soluble in organic solvents.
– They reflect UV light, creating a white appearance on plants, and contribute to water repellency.
– Glaucous foliage appears whitish due to the waxy covering.
**Epicuticular Wax Crystal Formation:**
– Wax crystals enhance water repellency, self-cleaning effects, and UV radiation reflection.
– Crystal shapes vary based on wax compounds present, with secondary alcohols forming hollow nanotubes and primary alcohols forming flat plates.
– Growth of wax crystals is observed using electron microscopes and atomic force microscopy.
**Measurement Techniques and Studies on Epicuticular Wax:**
– Analysis methods include Gas Chromatography Mass Spectrometry (GC-MS) and GC Flame Ionization Detection (GC-FID).
– Isotope ratio analysis (GC-IRMS) measures carbon and hydrogen isotopes in epicuticular waxes.
– Isotope studies using wax help in observing human evolution patterns and understanding plant metabolism and environments.
**Epicuticular Wax Biomarkers and Environmental Applications:**
– Epicuticular wax compounds serve as biomarkers for higher plants and are resistant to degradation.
– Their presence in marine sediments indicates transport from terrestrial environments.
– Studies on modern African environments using epicuticular wax proxies reveal insights into vegetation and hydrological changes influenced by orbital factors.
Epicuticular wax is a waxy coating which covers the outer surface of the plant cuticle in land plants. It may form a whitish film or bloom on leaves, fruits and other plant organs. Chemically, it consists of hydrophobic organic compounds, mainly straight-chain aliphatic hydrocarbons with or without a variety of substituted functional groups. The main functions of the epicuticular wax are to decrease surface wetting and moisture loss. Other functions include reflection of ultraviolet light, assisting in the formation of an ultra-hydrophobic and self-cleaning surface and acting as an anti-climb surface.