44 VEGETABLE ORGANOGRAPHY. 



are some who have considered them as representing the 

 stipules of the calycinal leaves : some believe them to 

 be one-flowered involucra ; founding this opinion upon 

 the irregularity of their presence, number, position, and 

 shape, which appears to indicate that they form part 

 rather of the organs of inflorescence than of the flower, 

 properly so called. The question will be resolved in 

 the affirmative, if a Malvaceous plant should be found 

 bearing 1 more than one flower within this external 

 covering. 



The bracts which arise at the base of the partial 

 umbels form what is called the Partial Involucrum, 

 or the Involucellum : those which grow at the base of 

 the peduncles, or general umbels, take the name of the 

 General Involucrum. In flowers in heads, we fre- 

 quently find one or more within a primary envelope ; 

 this is the involucellum : for example, in Echinops the 

 involucellum is one-flowered, with several imbricated 

 leaflets ; and in Lagasca it is also one-flowered, but the 

 leaflets are combined. These involucella, in the ex- 

 amples which I have mentioned, are collected into a 

 compact head, which is itself surrounded by an invo- 

 lucrum, to which the name of General Involucrum, or the 

 involucrum properly so called, is given, and they are 

 themselves sometimes surrounded by others more ex- 

 ternal. There is in general but little exactness in the 

 manner in which these parts are designated and com- 

 pared together, and great errors in description fre- 

 quently result. 



In a great number of capitate flowers, we find, besides 

 the scales of the involucrum, other bracts, situated be- 

 tween the flowers, and springing from the receptacle : 

 the leaflets of the involucrum are analogous to the bracts 

 which arise at the base of compound inflorescences ; the 

 scales of the receptacle represent the bracts belonging to 



