E0SACE7E. 



259 



XL POTEPJUM. POTERIUM. 



Herbs, with a perennial stock, ascending or erect annual stems, and 

 pinnate leaves. Flowers without petals, in dense, globular or ovate 

 heads at the ends of long peduncles, as in Sanguisorb, but most frequently 

 monoecious. Calyx in the males 44obed, the stamens numerous, with 

 long filaments. Calyx in the females tubular, contracted at the mouth, 

 with 4 small deciduous teeth. After flowering it becomes quadrangular, 

 closely enclosing 1 or rarely 2 one- seeded carpels. 



A small genus, chiefly south European and western Asiatic, gene- 

 rally preferring drier and more rocky situations than the Sanguisorbs. 



1. Burnet Poterium. Poterium Sanguisorba, Linn. 



(Fig. 321.) 



(Eng. Bot. t. 860. Salad Burnet. Garden Burnet.) 



A glabrous or very slightly downy 

 perennial, much like the Sanguisorb but 

 smaller, the stem seldom above a foot 

 high. Leaflets small, ovate, deeply 

 toothed, often 15 to 19 to each leaf. 

 Heads of flowers smaller and more glo- 

 bular than in the Sanguisorb, of a light 

 green colour, very seldom acquiring a 

 purplish tinge. Lower flowers all males, 

 with the numerous stamens projecting 

 in hanging tufts ; upper flowers female, 

 with a long style ending in a purple, 

 tufted stigma. Eipe calyx from 1 to 2 

 lines long, more or less distinctly quad- 

 rangular, and irregularly wrinkled and 

 pitted. 



In dry pastures and clefts of lime- 

 stone rocks, in central and southern 

 Europe, and temperate Russian Asia, 

 extending northwards into southern Sweden. In Britain, generally 

 spread over the limestone districts of England and Ireland, but scarce 

 in Scotland. The ripe calyx or fruit varies in size and in the pro- 

 minence of the wrinkles, constituting, in the eyes of southern botanists, 

 several distinct species ; one of these, with the ripe calyx near 2 lines 

 long, and very distinctly pitted and marked with little asperities, is 

 usually inserted in our Floras under the name of P. muricaticm. 



x 2 



Fig. 321. 



