1820.] Physical Science durincr the Year l^id. 119 



spike itself descendent; that is, the terminal spike is first ex- 

 panded, and the lower afterwards. The head of a compound 

 flower may be considered as a depressed spike, and when the 

 head is simple, the flowers expand from the circumference to the 

 centre ; but if the heads are placed in a corymbus, then the ex- 

 pansion of the heads, in respect to each other, proceeds from the 

 centre to the circumference. An attention to this observation 

 will show the real structure and proper appellation of the parts, 

 in cases where these points may be doubtful, as in Lagasca and 

 Ctesulia. This order of expansion of the florets is also of use 

 in determining the nature of some of the grasses; and is generally 

 accompanied with greater perfection of the parts, and apparently 

 a greater power of resisting the ordinary causes of abortion or 

 obliteration. Indeed the occasional reduction of any of the 

 parts of a flower is indicated by the expansion. The earlier ex- 

 pansion denoting greater perfection, and of course less liabilit}' to 

 reduction. And as wherever a separation of the sexes takes place, 

 the female flower may be assumed as the most perfect, so in 

 spikes and other compound inflorescences, the females are most 

 usually found in the parts that expand first. Of which Euphorbia 

 may be adduced as an example, although this genus was placed 

 by Linnaeus among the dodecandrous hermaphrodites, yet it is 

 in reality composed of several monandrous male flowers sur- 

 rounding a single female. The fasciculus of euphorbia is ca- 

 pable of being considered either as a simple depressed spike, or 

 as a compound spike, in which the central female flower is the 

 representative of the terminal spike, or as consisting of one or 

 more verticilli with a single flower in the centre. But althougli 

 in an assemblage of flowers priority of expansion generally in- 

 dicates a greater degree of perfection, yet in a hermaphrodite 

 flower the developement of the stamina usually precedes that of 

 the pistilla : the most remarkable exception occurring in some 

 species of plantago, where the stigmata are fully developed, and 

 often even withered, befoi'e the anthers burst. 



Mr. Brown then offers some remarks on certain genera of 

 compositEe, which either occur under different names in late 

 systematic works, or whose structure and limits seem to be im- 

 perfectly understood, viz. Soliva, Grindella, Tridax, Angianthus, 

 Meyera, Melampodium, Craspedia, Galea (to which he pays 

 particular attention), Isocarpa, Salmea, Baccharis, Brachylena, 

 Melananthera, Neuroltena, Antennaria, Ozothamnus, antl Cas- 

 sinia. 



The 4th volume of Kunth's Description of the new Genera 

 and Species of Plants observed by Humboldt and Bonpland, is 

 entirely devoted to this family, which he divides into six sections : 

 1. chichoraceae; 2. carduaceae; 3. eupatoreas ; 4'. jacobeae; 5.he- 

 liantheae; and, 6. anthemideae. He describes four genera as 

 new, but they had been already constituted bv Cassinl in the 

 Bull, de la Soc. Philom. 



