• 2 12 
BRITISH WILD FLOWERS. 
purple, like those of some of the other species ; but this plant is easily distinguished by the long spines of its 
involucre, and by its leaves appearing blotched with white, as though milk had been spilt on them. 
GENUS XXXI. 
THE SAW-WORT. (Serratula, Lin.) 
Lin. Syst. SYNGENESIA iEQUALIS. 
Generic Character. —Dioecious. Involucrum imbricated ; scales unarmed, acute. Receptacle paleaceous ; the palese split into numerous 
linear bristles. Pappus persistent, with rigid unequal hairs. ( Lindley .) 
Description, &c. —There is only one British species belonging to this genus, viz. the common Saw-wort 
( S . tinctoria , Lin.), which is a perennial plant, producing its flowers in July and August. The genus takes its 
names of Serratula and Saw-Wort from the deep serratures of its leaves; and the specific name of the species, 
tinctoria , alludes to the juice of the plant being occasionally used to dye yellow. 
GENUS XXXII. 
THE CENTAUREA. (Centaurea, Lin.) 
Lin. Syst. SYNGENESIA FRUSTRANEA. 
pale* jagged. Fruit inserted obliquely at the ba3e. Pappus hairy. 
(Lindley.) 
Generic Character. —Involucrum imbricated ; scales leafy, sca- 
rious, or spiny in various ways. Florets of the disk hermaphrodite ; 
of the ray neuter and larger than the others. Receptacle paleaceous ; 
Description, &c.— This is a very extensive genus, varying exceedingly in the form, colour, and habit of 
growth of the plants, but agreeing in their qualities, which are all bitter and tonic. The name of Centaurea is 
said to be derived from the.Centaur Chiron, the preceptor of Achilles, who used it for curing wounds. The genus 
is placed in the Linnaean class and order Syngenesia Frustranea, because the florets of the ray have neither stamens 
nor pistils. 
* Scales of involucrum jagged or fringed. 
1.—THE BLACK KNAPWEED. (Centaurea nigra, Lin.) 
upright capillary teeth. Lower leaves somewhat lyrate, with angular 
lobes ; upper ones ovate. Flowers discoid. (Lindley.) 
Engravings. —Eng. Bot., t. 278; 2nd ed., t. 1187; and our fig, 
5, in PI. 42. 
Specific Character. —Scales of involucrum oval, fringed with 
Description, &c.— This species is common in meadows and pastures, and on road-sides in every part of Great 
Britain; and it is distinguished from the other species of Knapweed by the scales of the involucrum being 
black. It is a perennial plant, and flowers from June till September. 
2.— THE CORN BLUE-BOTTLE. (Centaurea Cyanus, Lin.) 
Engravings. —Eng. Bot., t. 277 ; 2nd cd., t. 1188. 
Specific Character. —Scales of involucrum serrated. Leaves linear-lanceolate, entire ; lower ones toothed towards their base. (Lindley.) 
Description, &c.— This beautiful plant is one of the common weeds of almost every corn-field, and is, of 
course, generally well known. It is an annual, and it produces its brilliant blue flowers in July and August. 
