What part off the plant does the lavender oil come from?

True lavender essential oil is extracted by steam from the fresh flowering tops of Lavandula angustifolia.

Spike Lavender oils is extracted by steam or water from the flowering tops of Lavandula latifolia.

Lavandin essential oil is extracted by steam from the fresh flowering tops of Lavandula x intermedia. This for produces larger quantities of oil than does the the true or spike form.