196 



" The whole of Composite agree in two remarkable points of structure of 

 their corolla ; which, taken together at least, materially assist in determining 

 the limits of the class. The first of these is its valvular estivation ; this, 

 however, it has in common with several other families. The second I believe 

 to be peculiar to the class, and hitherto unnoticed. It consists in the disposi- 

 tion of its fasciculi of vessels or nerves ; these, which at their origin are 

 generally equal in number to the divisions of the corolla, instead of being 

 placed opposite to these divisions, and passing through their axes as in other 

 plants, alternate with them ; each of the vessels at the top of the tube divid- 

 ing into two equal branches, running parallel to and near the margins of the 

 corresponding laciniae, within whose apices they unite. These, as they exist 

 in the whole class, and are in great part of it the only vessels observable, may 

 be called primary. In several genera, however, other vessels occur, alternating 

 with the primary, and occupying the axes of the laciniae ; in some cases these 

 secondary vessels being most distinctly visible in the lacinie, and becoming 

 gradually fainter as they descend the tube, might be regarded as recurrent, 

 originating from the united apices of the primary branches ; but in other cases, 

 where they are equally distinct at the base of the tube, this supposition cannot 

 be admitted. A monopetalous corolla not splitting at the base is necessarily 

 connected with this structure, which seems also peculiarly well adapted to the 

 dense inflorescence of Composite, the vessels of the corolla and stamina 

 being .united, and so disposed as to be least liable to suffer by pressure." 

 JR. Brown Linn. Trans. 12. 77. 



Geography. All parts of the world abound in Composite, but in very 

 different proportions. According to the calculations of Humboldt, they con- 

 stitute | of the phenogamous plants of France, \ of Germany, T j of Lap- 

 land, in North America £, within the tropics of America \ ; upon the autho- 

 rity of Mr. Brown, they only form T \ of the Flora of the north of New 

 Holland, and did not exceed ~ in the collection of plants formed by Dr. Smith 

 upon the western coast of Africa in Congo. Congo, 445. In Sicily they 

 constitute rather more than ■*■ (Presl.) ; the same proportion exists in the 

 Balearic Islands (Cambesstdes) ; but in Melville Island they are rather more 

 than Jg (Broion), a proportion nearly the same as that of the tropical parts of 

 New Holland. It does not, therefore, appear that Composite, as an order, are 

 subject to any very fixed ratio of increase or decrease corresponding with 

 latitude. But much remains to be learned upon this subject. It is certain 

 that Cichoracee are most abundant in cold regions, and Corymbifere in hot 

 ones ; and that while in the northern parts of the world Composite are uni- 

 versally herbaceous plants, they become gradually frutescent, or even arbo- 

 rescent, as we approach the equator ; most of those of Chile are bushes, and 

 the trees of St. Helena are chiefly Composite. 



Properties. I shall extract the substance of Decandolle's excellent 

 remarks upon the properties of this family, with some additions. See Essai 

 sur les Propri£t£s, §c. 177. 



They are best considered under the three principal heads of classification. 



CoRYMBIFERiE. 



There is a bitterness peculiar to all Composite, which in this section assumes 

 a particular character, being combined with a resinous principle. If this latter 

 exists in an inconsiderable quantity, and mixed with a bitter or astringent 

 mucilage, we find tonic, stomachic, and febrifugal qualities, as in Tussilago 

 Farfara, Camomile, Elecampane, Golden Rod, Matricaria Parthenium, the 

 Stevia febrifuga of Mexico, and Eupatorium perfoliatum. The Inula Hele- 

 nium, or Elecampane, has a root which is aromatic and slightly fetid. It is 

 said to be of little value as a stomachic ; the French prepare from it a medi- 



