Cymbopogon nardus is the Source of Citronella Oil

Citronella oil, valued for its insect-repellent properties, is extracted from Cymbopogon nardus (Ceylon citronella grass), making option (3) correct. This perennial grass yields 1-1.5% oil via steam distillation of leaves.

Introduction

Citronella oil obtained from Cymbopogon nardus provides citronellal (35-45%), geraniol (15-20%), and citronellol for perfumes, repellents, and aromatherapy. This essential oil crop thrives in tropical climates. This guide evaluates all options for botany exam accuracy.

Option Analysis

Citronella oil production: Steam distillation of fresh/dried leaves; Java (C. winterianus) and Ceylon (C. nardus) chemotypes.​

• (1) Linum usitatissimum: Incorrect. Flax/linseed (Linaceae); produces linseed oil (edible/drying) from seeds rich in α-linolenic acid (ω-3). No citronella volatiles.​

• (2) Glycine max: Incorrect. Soybean (Fabaceae); yields soybean oil (cooking, biodiesel) from seeds (~20% oil: oleic, linoleic acids). No lemongrass-like terpenoids.​

• (3) Cymbopogon nardus: Correct. Ceylon citronella grass (Poaceae); steam distillation yields pale yellow oil (yield 0.8-1.2%). Major: citronellal (40%), geraniol (18%), limonene (10%).

• (4) Elaeis guineensis: Incorrect. Oil palm (Arecaceae); produces palm oil (red, rich in palmitic/oleic) from mesocarp (~45% oil yield). Used in food, cosmetics; no insect-repellent monoterpenes.​

Chemical Profile & Production

Ceylon vs. Java Citronella:

Cultivation: Sandy loam, pH 5.5-6.5, 1500-2500 mm rain; harvest 4-6 months, 3-4 cuts/year. India: Karnataka, Tamil Nadu major producers.

Applications

• Repellent: Citronellal disrupts mosquito olfaction (90 min protection)

• Perfumery: Rose-like odor (geraniol)

• Pharma: Antifungal, anti-inflammatory

Exam Relevance

GATE Life Sciences/Agriculture: Cymbopogon nardus = Citronella (vs. lemongrass C. citratus = citral). Mnemonic: “CYMBOpogon = CYMBOl of Citronella.”​