146 



LEGTJMINOSAE. 



CYTISUS. Broom. 

 (Family Leguminosae). 



Shrubs, usually rather small: 

 commonly deciduous. Twigs slen- 

 der, terete or more usually ribbed 

 or grooved: pith small, roundish, 

 continuous. Buds small, solitary, 

 sessile, round-ovoid, with about 4 

 often indistinct scales. Leaf-scars 

 alternate, elevated, minute: bun- 

 dle-trace 1, indistinct: stipules or 

 minute stipule-scars at top of the 

 leaf-cushion. Cytisus scoparius is 

 frequently referred to as Spar- 

 tium; and Laburnum, as Cytisus. 



1. Twigs forming blunt slender 



spines. (1). C. pungens. 



Not at all spiny. 2. 



2. Twigs distinctly ridged or 



angular, never villous. 3. 



Twigs obscurely ridged, staring- 

 pubescent. (2). C. nigricans. 



Twigs terete. 6. 



3. Twigs narrowly ridged. (3). C. canariensis. 

 Twigs prominently angled or ridged. 4. 



4. Twigs finely granular, almost winged. (4). C. scoparius. 

 Twigs not granular. 5. 



5. Twigs glabrescent or appressed-pubescent. 



(5). 

 Twigs quite glabrous. 



6. Pubescence rather short and appressed. 

 Pubescence long and loose. 7. 



7. Erect. 



Low and spreading. 



References on p. 148. 



C. glabrescens. 

 C. purpureus. 

 C. leucanthus. 



C. hirsutus. 

 C. supinus. 



