SANDAL WOOD 181 



with stinging hairs; the leaves are ovate with long petioles, the 

 summit being acute or acuminate; the base cordate; the margin 

 very deeply serrate with triangular or lanceolate teeth; the lower 

 surface is pubescent, as is also the upper part of the stem. The 

 flowers are dioecious or androgynous and occur in much branched 

 spikes. 



The presence of stinging hairs was long known, being referred to 

 by Pliny. Their structure was examined in detail by Haberlandt. 

 They are unicellular, rather long and conical, the summit bearing a 

 small spheroidal or ovoid head, which is obliquely inserted, and readily 

 breaks off, thus leading to the emission of the contents of the stinging 

 hair. The hair is frequently seated on a multicellular pedestal, which 

 surrounds its base like a cup, and is partly formed by the periblem. 

 The nature of the wall of the stinging hairs is peculiar. The head and 

 the neighboring portions of the wall of the hair are silicified; in the 

 latter the amount of silicification gradually decreases toward the 

 base of the hair, and finally is entirely replaced by the calcification. 

 It is the unequal thickening of the walls of the head that causes the 

 characteristic line of fracture and the emission of the cell sap on 

 slight pressure. 



Constituents. It was formally stated that the stinging action 

 is due to the presence of formic acid. In the light of later research 

 this seems doubtful and the activity is now ascribed to a ferment. 

 The plant contains a glucoside, tannic acid, mucilage, a coloring 

 principle and possibly also an alkaloid. 



SANTALACE.E, OR SANDALWOOD FAMILY 



Mostly shrubs or trees that are indigenous to the tropics. A 

 few are found growing in the United States, as the Oil-nut or Buf- 

 falo-nut (Pyrularia pubera), the fleshy fruit of which is edible and 

 the seeds contain an acrid fixed oil. Others are parasitic on the 

 roots of other plants. The following anatomical features of this 

 family may be mentioned: The wood is of uniform structure and 

 consists of tracheae having simple and bordered pores, and tracheid- 

 like wood fibers, i.e., with bordered pores. In the pericycle of the 

 bark occur isolated bundles of primary bast fibers, a ring of scleren- 

 chyma being rarely developed in the secondary phloem. In the 

 leaves are found groups of silicified cells and calcium oxalate occurs 

 in the form of rosette aggregates or solitary crystals. The hairs 

 when present are non-glandular and unicellular. 



