INTRODUCTION. XXV 



ANDRIA, Order MONOGYNIA (p. xlvii), and will proceed 

 to read the characters of the genera there described, com- 

 paring such descriptions with his specimen. - Opposite 

 the first genus, Delphinium, he will find the characters, 

 " Sepals 5, coloured, the upper one spurred/' This is 

 no description of his plant, so he passes on to 2. 

 Papdver : "Sepals 2" &c. He reads no further, but 

 passes 011 to 6. Actcea : " Sepals 4." Neither will this 

 do, for his plant has 5 sepals, of which the two outer 

 are much smaller than the rest. The next, genus 7. 

 Helidnthemum, has "Sepals 5, the two outer smallest, 

 or sometimes wanting , petals 5." To this genus, then, 

 his plant belongs ; the short description which follows 

 also suits his plant : " Small shrubs with oblong leaves, 

 and showy, white or yellow flowers." He is then 

 referred to the EocK-EosE TRIBE (p. 74), where are 

 enumerated the leading characters of the Tribe and of 

 all the British genera included in it. Being assured, by 

 a perusal of these, that his plant belongs to the genus 

 Helidnthemum, he proceeds to ascertain its species, and 

 finally satisfies himself that he holds in his hand a 

 specimen of a plant known among botanists by the 

 name of Helidnthemum vulgdre (Common Eock-Eose). 



To take another example. The plant of which it is 

 desired to discover the name is an erect, herbaceous 

 plant, with smooth leaves and long spiked clusters of 

 green flowers. The number of stamens here is variable, 

 so that there is some doubt whether it should be referred 

 to the Class DODECANDRIA, including plants with from 

 12 to 20 stamens, or to .the Class POLYANDRIA, with 

 more than 20. About the number of pistils, however, 

 there can be no doubt they are distinctly 3. Accord- 

 ingly, if we turn to Class DODECANDRIA, Order TRIGYNIA 

 (p. xlvii.), we find only the genus "Reseda. Herbaceous 

 or somewhat shrubby plants with furrowed stems, 

 smooth leaves, and terminal spikes or clusters of 

 greenish flowers." This description is accompanied by 

 a reference to the EOCKET-TRIBE (p. 72). If, on tho 



