THE INCOMPLET^E 45 



stipule is very characteristic, as it is membranous and 

 encircles the stalk on which it is borne. Again, the 

 flowers are always unisexual, because each bears either 

 stamens only or carpels only, never both together. The 

 male or staminate flower consists of a periantli of 3-6 

 members, and there are usually 5-8 stamens. The 

 female or carpellary flower has the same kind of peri- 

 anth, and a pistil with either 2 or 3 styles (h'g. 22). 

 Further, the fruit differs from almost all others in 



Lastly, the 



having a flattened or triangular structure, 

 inflorescence is an outstanding feature, 

 for although the flow^ers are small there 

 are plenty of them, and they crowd the 

 stalk which rises erect above the rest of 

 the plant. 



Speaking generally, care must be ob- 

 served in dealing wdth this family, as 

 there is apt to be a marked diflerence in 



i. Fig. 2i.— DiJigram 



the properties of the various parts. Thus ^f Female Fiower 

 the leaves and leaf -stalks are generally of Poiysonuctae 



acid and astringent, and in some cases, as 

 in the Rlmbarb, agreeable to the taste, while the roots 

 are nauseous and purgative. The fact that one part of 

 the plant can be eaten with impunity furnishes no 

 guarantee regarding the edibility of tlie other parts of 

 the plant 

 British Genera: — 



1. Polygonum.— Fruit a flattened or triangular nut. 



2. RuMEX (Dock).— Fruit a triangular nut covered by 



an enlarged inner loerianth, 



3. OXYRIA (Mountain Sorrel). 



Rhubarb (i^A^um).— The commercial drug known as 

 Rhubarb is the rhizome of a species of Rheum which 

 glows wild in North- West China and Eastern Tibet. 



