108 FLOWE&S. 



(57) Santonica. 



The unexpanded capitula of Artemisia maritima, var. a- 

 Stechmanniana, Besser (N.O. Composites). 



The capitula are very small, being only about 2 Mm. long, 

 elongated and ovoid in shape ; their surface is shining and 

 glabrous. 



The involucre consists of about ten to fifteen imbricated 

 bracts. The lower of these are ovate in outline, and smaller 

 and more distant than the upper ones, which are elongated. 

 They are furnished with a conspicuous keel, on each side 

 of which numerous oil-glands can be seen. The young bracts 

 bear a few colourless woolly hairs over the midrib, but these fall 

 off towards maturity. The upper bracts enclose from three to five 

 florets inserted upon a naked receptacle. The corolla of each 

 floret is contracted at the base, and divides at the apex into five 

 short triangular teeth. 



The involucral bracts are composed of a central opaque por- 

 tion bordered on each side by membranous translucent wings, 

 on which numerous oil-glands are borne. The epidermis of the 

 translucent portion consists of elongated cells, but that of the 

 central portion is composed of isodiametric cells with pitted 

 walls. The latter portion bears numerous stomata, glands, and 

 one-celled woolly hairs ; the glands have the shape and struc- 

 ture characteristic of composite plants. 



The transverse section varies a little according to the position 

 of the bract on the axis, but there are certain general characters 

 common to all of them. The midrib is flat on the inner sur- 

 face of the bract, but angular on the outer. The substance of the 

 bract is composed of rounded, polygonal or cylindrical paren- 

 chymatous cells containing chlorophyll, and is traversed by a 

 fibro-vascular bundle. Below the outer epidermis of the peri- 

 pheral bracts there is a curved hypoderma consisting of one or 

 two rows of sclerenchymatous cells. A secretory duct may 

 sometimes, but not always, be found within the endodermis, 

 between the midrib and the epidermis of the upper (inner) sur- 

 face of the bract. 



The lower part of the corolla-tube bears a number of oil- 

 glands ; indeed this part of the plant appears to be richer in oil 

 than any other. 



The diagnostic characters of powdered santonica are : 



(a) The epidermis of the central portion of the bracts with 



pitted walls, numerous stomata, and woolly hairs. 



(b) The characteristic oil-glands. 



(c) The elongated, thickened cells of the hypoderma of the 



bracts. 



