BE TULA 



79 



and the mangold-wurzel. The plant is a biennial and stores reserves 

 in the root, the non-nitrogenous materials taking the form of sugar. 



The sugar-beet is largely cult, in W. Eur. for its sugar, a for- 

 midable rival to the older industry of cane sugar. The sugar-contents 

 of the roots have been continually improved by selection, and now 

 frequently represent over 2O/ of the weight. Germany grows ii 

 million tons of beet sugar annually, and other countries about 

 another 3 millions. [Herzog, Monographic der Zucker-riibe, Ham- 

 burg, 1899.] 



The garden beet is a favourite vegetable ; the mangold is valuable 

 for feeding cattle, &c. The 1. are sometimes eaten like spinach. 



Betckea DC. = Plectritis DC. (Valerian.). 



Betel-nut, Areca Catechu L. ; -pepper, Piper Betle L. 



Betonica (Tourn.) Linn. =Stachys Tourn. (Labial.). 



Betony, Stachys. 



Betula (Tourn.) L. Betulaceae (2). 38 N. temp., arct. B. alba L., 

 the birch, is common in Brit, and reaches to the N. limit of trees, 

 which is occupied by B. nana L. , a creeping shrubby form, in much 

 of the N. temp. zone. The winter buds are scaly, the scales 

 representing stips. : the outer two or three pairs of them have no 1. 

 Witches' brooms are very commonly to be seen as dense tufts of twigs. 

 Trees with catkins of fls. The <? calkins are laid down in autumn 

 as large buds at the end of the year's growth, ihe ? furlher back, on 



B. alba. A, bract, bracteoles, and perianth, of $ , from within, with sta. re- 

 moved ; B, a stamen ; C, floral diagram of A ; D, bract, bracteoles and fls. of ? 

 from within ; E, the same with fls. removed ; /', the same at ripeness of seed ; G, 

 floral diagram of D. b = bract ; a. /3 = bracteoles of fl. i, or bracts of fls. 2, 3. After 

 Eichler. 



leafy branches. In the axil of each 1. of the catkin there are 3 fls. 

 (cf. other genera of B.). The bracts of the lateral fls. occur (a, /3) 

 but no bracteoles. In the 3 the bracteoles a /3 are joined to ihe 

 bract itself. Each fl. has l\vo sta. and a perianlh, often reduced from 

 the typical 4 1. to the 2 median 1. , or even to ihe single anterior 1. 

 The sta. are divided into halves nearly lo ihe base ; the lat. ones are 

 absent. In ihe ? the bracteoles a /3 are free from the bract al ihe 

 lime of fertilisation, but afterwards they unite \vith it to form the 

 3-lobed woody scale (F in figure) under the fruit (or rather the tissue 



