Poterium.] XXVI. ROSACES. 141 



X. POTERIUM. 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 Sanguisorba, but most fre- 

 quently moncEcioas. Calyx in the males 4-lobed, the stamens numerous, 

 with long filaments. Calyx in the female tubular, contracted at the 

 mouth, with 4 small deciduous teeth. After flowering it becomes quad- 

 rangular, closely enclosing 1 or rarely 2 1- seeded carpels. 



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

 rally preferring drier and more rocky situations than the Sanguisorbas. 



1. P. Sanguisorba, Linn. (fig. 327). Salad Burnet. A glabrous or 

 very slightly downy perennial, much like the Sanguisorba 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 globular than in Sanguisorba, 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. Ripe calyx from 1 to 2 lines 

 long, more or less distinctly quadrangular, and irregularly wrinkled and 

 pitted. 



In dry pastures and clefts of limestone 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, but scarce in Scotland and Ireland. The ripe calyx or fruit 

 varies in size and in the prominence 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 P. muricatum, Spach. 



XI. AGRIMONIA. AGRIMONY. 



Herbs, with a perennial stock, erect stems, pinnate leaves with dis- 

 tinct segments or leaflets, and yellow flowers in long, terminal, simple, 

 loose spikes. Calyx 5-toothed. Petals 5. Stamens few. Carpels 

 usually 2, enclosed within the dry, persistent calyx, which is covered, 

 when ripe, with hooked bristles. 



The genus comprises but very few European, north Asiatic, and 

 North American species, easily known by their inflorescence and their 

 fruit. 



1. A. Eupatoria, Linn. (fig. 328). Agrimony. Stems 2 or 3 feet 

 high, more or less clothed, as well as the leaves, with soft hairs. Lower 

 leaves often 6 inches long, with from 5 to 9 distinct, ovate, coarsely 

 toothed leaflets, about an inch long, intermixed with a number of much 

 smaller ones ; the upper leaves gradually smaller, with fewer leaflets. 

 Spike long and leafless, but each flower in the axil of a small 3-cleft 

 bract, with 2 smaller 3-toothed bracteoles on the very short pedicel. 

 Tube of the calyx hairy and erect when in flower, turned downwards 

 after flowering, when it becomes thickly covered at the top with hooked, 

 green or reddish bristles, forming a small burr. Petals rather small, 

 oblong. Stamens short, often not more than 6 or 7, but sometimes 

 twice that number. 



On roadsides, waste places, borders of fields, &c., over nearly the 



