Cymbopogon flexuosus the source of commercial citronella oil occurs in two cultivated forms (i) Lena Batu and (ii) Maha Pengiri or old Citronella Grass, also known as Winter Grass. The plant attains a height of 36-60inch. The leaves are alternately arranged, parallel veinel, one mt. in length. The flowers are zygomorphic and arranged in terminal panicles. Each flowering unit is a spikelet at the base of which are 2 yellow-brown structures called glumes. The spikelets are in pairs. The lower spikelet is pedicellate with the pedicel covered with pubescence, while the upper spikelet is sessile. In each spikelet there are 2 flowering structures each is subtended by 2 additional structures (lemma and palea). The lower unit is fertile and has 3 unfused stamens and a superior ovary with a single locule and seed. The palea of the fertile spikelet has an awn to 8 mm in length. The upper unit is sterile. The fruit is a caryopsis at maturity. The latter has been raised to the status of a separate species, C. winterianus Jowitt. Both forms are cultivated in Ceylon, but at present lena batu is the more extensively cultivated as it is hardy, grows on poor soil and does not require much attention. It is grown also in Seychelles. Maha pengiri is the principal cultivated citronella grass of Java.