THYME 575 



cell; (6), without a stalk and having an 8- to 12-celled secreting head, 

 the latter being yellowish-brown in color and about 0.015 mm. in 

 diameter, giving the leaves a glandular punctate appearance. Calyx 

 having 6- to 8-celled uniseriate hairs, which are long pointed, from 

 0.300 to 0.400 in length, the walls being thin and the lumina of the 

 lower cells filled with air. In the stem the endodermis is distinct; 

 the pericycle is made up of a narrow ring of sclerenchymatous fibers; 

 and the medullary rays of the xylem are 1 cell in width. 



Constituents. A yellowish-red volatile oil, from 1 to 2.6 per cent, 

 consisting of thymol, cymene, thymene and a small quantity of 

 1-pinene. Spanish oil of thyme is often of a dark green color and con- 

 tains from 50 to 70 per cent of carvacrol, but no thymol. Thyme 

 also contains tannic acid. 



Standard of Purity. Thyme is the dried leaves and flowering 

 tops of Thymus vulgaris L. It contains not more than 14 per cent of 

 total ash, nor more than 4 per cent of ash insoluble in hydrochloric 

 acid. (U. S. Dept. Agric.) 



Allied Plant. Thymol may be obtained from horsemint (Mon- 

 arda didyma). See bulletin 372, U. S. Dept. Agric. 



Adulterants. The leaves and tops of CRETAN DITTANY, Origa- 

 num Dictamnus, a native of the Isle of Crete in the eastern Med- 

 iterranean Sea, are sometimes sold as thyme. The stems are nearly 

 cylindrical, reddish-brown, from 0.5 to 2 mm. in diameter. The 

 leaves are broadly elliptical, light greenish-gray and densely tomen- 

 tose. The bracts are purplish-brown and the corolla dark purple. 

 The plant yields a volatile oil containing about 85 per cent of pule- 

 gone. 



The leaves and tops of Origanum creticum, known as SPANISH 

 HOPS, is also sold for thyme. The plant is indigenous to southern 

 Europe and consists of numerous cylindrical or somewhat quad- 

 rangular stems of a yellowish or light brown color; a number of 

 elliptical or ovate, short petiolate leaves, about 10 mm. in length, 

 being grayish-green, glandular hairy and with 5 palmate veins; and 

 numerous ovoid or cylindrical spikes having grayish-green imbri- 

 cated bracts and enclosing in fruit the ovoid nutlets; the latter 

 being elliptical, yellowish-brown, about 1 mm. in length and having 

 the epidermal cells modified to papillae. The plant yields from 2 to 3 

 per cent of a volatile oil containing from 60 to 85 per cent of'carvacrol. 

 The oil, from different sources, varies in color and in the carvacrol 

 content. Ocymum viride, native of west Africa, yields 0.45 per cent 

 of volatile oil which contains 52 per cent of thymol. Bot. Abstracts, 

 1918, 1, p. 114. 



