The L. multifida is synonymous with L.  Burmanii.  In Spain the therapeutic properties of L. dentata are alleged to be even more marked than in the oils of any of the other species of lavender.  It is said to promote the healing of sluggish wounds, and when used in the form of inhalation to have given good results in cases of severe catarrh, and even in cases of diphtheria.  In odor this oil strongly suggests rosemary and camphor.  Its specific gravity is 0.926 at 15 deg.  C. It distills almost completely between 170 deg. and 200 deg..

The specific gravity of the oil of L. vera (according to Flueckiger and Hanbury, Pharmacographia) ranges between 0.87 and 0.94.  The same authorities state that in a tube of 50 millimeters the plane of polarization is diverted 4.2 deg. to the left.

Dr. Gladstone found (Jnl.  Ch.  Soc., xviii., 3) that a sample of pure oil of L. vera, obtained from Dr. S. Piesse, indicated a specific gravity of 0.8903 at 15 deg.  C., and that its power of rotating the plane of polarization (observed with a tube ten inches long) was -20 deg..  Compared with these results he found the sp. gr. of oil of turpentine to be 0.8727, and the rotatory power -79 deg..

Although L. staechas was well known to the ancients, no allusion unquestionably referring to L. vera has been found in the writings of classical authors, the earliest mention of this latter plant being in the twelfth century, by the Abbess Hildegard, who lived near Bergen-on-the-Rhine.  Under the name of Llafant or Llafantly, it was known to the Welsh physicians as a medicinal plant in the thirteenth century.  The best variety of L. vera—­and there are several, although unnamed—­improved by cultivation in England, presents the appearance of an evergreen undershrub of about two feet in height, with grayish green linear leaves, rolled under at the edges, when young; the branches are erect and give a bushy appearance to the plant; the flowers are borne on a terminal spike, at the summit of along naked stalk, the spike being composed of six to ten verticillasters, more widely separated toward the base of the spike; in young plants two or four sub-spikes will branch alternately in pairs from the main stalk; this indicates great vigor in the plant, and occurs rarely after the second year of the plant’s growth.  The floral leaves are rhomboidal, acuminate, and membraneous, the upper ones being shorter than the calyces, bracteas obovate; the calyces are bluish, nearly cylindrical, contracted toward the mouth, and ribbed with many veins.  The corolla is of a pale bluish violet, of a deeper tint on the inner surface than the outer, tubular, two-lipped, the upper lip with two and the lower with three lobes.  Both the corolla and calyx are covered with stellate hairs, among which are embedded shining oil glands, to which the fragrance of the plant is due.  The L. vera was identified in 1541, and introduced into England in 1568, flourishing remarkably well under cultivation, and yielding an oil far superior in delicacy of fragrance to that obtained from the wild plant, or to that obtained from the same plant cultivated in any other country.