6 PLANTS OF MASSACHUSETTS. 



The Vasculares, those possessed of flowers, form two great 

 subdivisions, according to their manner of growth, called Exogenoz 

 and Endogence. In the Exogenous plants, the growth is by 

 layers, or a deposition of matter upon the outside, as shown in the 

 concentric layers of trees and shrubs ; in the Endogenous plants, 

 the growth is by a deposition of matter within the plant. In the 

 former, the bark, wood, pith, &c, are readily distinguished ; 

 in the latter, they are not. In the former, too, the new and 

 delicate matter is protected by the bark, from the inside of 

 which it is made ; in the latter, the same protection is effected 

 by the place of its deposit in the interior of the plant. 



The Vasculares are propagated by seeds, and are chiefly char- 

 acterized by the leaves. Some are propagated also by bulbs or 

 roots, and are found in the Endogenous division. The leaves 

 of the Exogenous plants have branching or netted veins very 

 generally ; but the Endogenous usually have veined leaves, or 

 leaves with veins rising from the foot-stalk, and running through 

 the leaf either curved or straight, and parallel and undivided. 

 By the veining of the leaves, these two important subdivisions 

 are, as a general fact, readily distinguished. 



The seeds of the Exogenae have two cotyledons, or are di- 

 cotyledonous ; those of the Endogenae are monocotyledonous. 



A "Catalogue of Plants growing without Cultivation " in the 

 Commonwealth, arranged according to the Natural Method of 

 Lindley, as published and applied to the plants of this country by 

 Professor Torrey of New York, was given by Professor Hitch- 

 cock in the Geology of the State already published by the Legis- 

 lature. The Orders of this "Catalogue," have been followed 

 in this Report on the Herbaceous plants, with the addition of 

 such Orders from Lindley, as the introduction of the cultivated 

 plants has made necessary. The changes made in some of these 

 Orders, both in Europe and our own country, are not sufficiently 

 settled to require a departure from the Orders of Lindley. It 

 was thought best, also, to follow these Orders, that the whole 

 Survey might be more symmetrical, and reference to the various 

 parts more easy and satisfactory. For the same reason, the 

 names of the genera and species in Professor Hitchcock's Cata- 

 logue have been retained, even in the few cases where it might 



