LESSONS IN BOTANY. 



209 



LESSONS IN BOTANY. \\ 



ION xxxviii. COMPOSITE:, OB COMPOSITB- 



1 I.OWI.KKU i'LANl.-" uliiiwd). 



WE must not omit to mention, while discussing the various 



means taken advantage of by Nature to promote the dissemina- 



tion of Composites, a very irrotesque arrangement possessed by 



species, in virtue of which animals are made the unoon- 



l>earers of the precious vegetable charge. The bract 



whi.-h we have already seen competent to assume so many 



shapes, becomes in certain species of this natural order hooked, 



uovering each involucre with hundreds of claw- like arms. Who 



has not seen this curious provision on the burdock, though, 



perhaps, the utility of this singular appendage has not sug- 



itself P The use of this hook, no doubt, is for the pur- 



pose of causing the torus to lay hold of the skins of animals or 



other passing objects. 



The Composites being a natural order which includes so large 



the circumstance of having imbricated estivation and free 

 rs, by the presence of an invoiucrum surrounding each 

 flower ; lastly, by the pendant and albuminous seed. 



The grsat family, Comporitas, U dispersed all over the globe ; 

 nevertheless, the number both of species and of individual* 

 rapidly diminishes towards either pole, and slightly towards the 

 Equator. They chiefly inhabit temperate and hot region*, more 

 especially tropical islands, and districts on the sea-coast ot 

 tropical continents. America is richest in number of specie*. 

 Herbs belonging to this order grow in climat** which are 

 temperate and cold ; shrubs in regions still hotter ; and tree* 

 in the hottest of all. Moreover, the latter are exclusively con- 

 fined to intertropical and antarctic islands. Tubuliflora are 

 numerous between the tropics, LiguliflorcB in the northern tem- 

 perate region. LaliatiflvroK are rare ont of America, where they 

 abound between the Equator and the Tropic of Capricorn. 

 Whatever may be the locality of any one species belonging to 

 this order, it is rare that it can be naturalised elsewhere. IB 



173. THE COEK CENTAUREA, OE CORN-FXOWER (CENTATTRIA 

 CYANEA). 174. THE COMMON MARIGOLD (CALENDULA 

 OFFICINALIS). 175. THE DANDELION (LEOXTODON 

 TAKAXACVM, OK TARAXACUM OFFICINALE). 



a number of species, some kind of subordinate classification 

 becomes necessary. Botanists are by no means agreed as to 

 the best method of accomplishing this. Perhaps the system of 

 Decandolle and Endlicher is most generally convenient : accord- 

 ing to which the order Composites is divided into three series ; 

 first, LiguliflorcB, or strap- shaped flowers, from the Latin ligula, 

 i strap ; second, Labiatiflorce, or lip-shaped flowers, from the 

 Latin labium, a lip ; third, Tubuliflorce, or funnel-shaped 

 flowers, from the Latin tubulus, a funnel or small tube. These 

 sub-families are divided into eight tribes, which are again 

 divided into genera, and so each species is arrived at. 



There are a few natural orders which, regarded in the tout 

 ensemble of their general characteristics, approach the Compo- 

 sites. The little family of Calyceracece presents a great analogy 

 with them, both as regards the inflorescence and the structure 

 of individual flowers. It differs from Composites, however, in 

 the circumstances that the seed, instead of being erect at the 

 base of the ovary, is suspended from the summit of the latter ; 

 that the embryo is enclosed in a fleshy albumen ; that the radicle 

 is superior ; that the style, always undivided, is terminated by a 

 iMwtiilar sticma. Next come the Dipsacece, of which the greater 

 portion resemble the Composites by their inflorescence being that 

 of a capitular invoiucrum : but which differ from the family in 

 40 N.E. 



this respect the Compositce are peculiarly unbending ; neither 

 care nor culture will generally suffice to effect a permanent 

 reconciliation between the transported plants and their new 

 homes ; to this, however, there are many exceptions. 



The immense family of Comjositos furnishes mankind with 

 numerous useful products, some of which will now be rapidly 

 enumerated. The radiated Tubuliflorce, regarded in the aggre- 

 gate, may be said to contain in the flower a bitter principle com- 

 bined with a resin or volatile oil ; associated with these there is 

 frequently discoverable in the root a material something resem- 

 bling starch, and designated chemically by the specific name 

 inuline, because it is chiefly found in the elecampane (Inv.la). 

 According to the mutual proportions in which one or another 

 of these bodies may predominate, the various species become 

 endowed with different medicinal properties. Some are tonics, 

 others excitants or stimulants, others are astringents. The 

 great genus Artemisia, represented throughout all the world by 

 different species, furnishes us with various bitter aromatics, the 

 properties of many of which have been celebrated from periods 

 of very high antiquity. Two species, Artemisia Absinthium, and 

 Artemisia Pontica, are indigenous. Southernwood, or Arte- 

 misia Abrotanum, originally from the East, is now cultivated iu 

 our gardens, and of world-wide reputation for its penetrating 



