103 SUBDIVISIONS. 



of their two different modes of growth. The first of these divisions 

 is called, as we have before noticed in speaking of stems, exogenous, 

 or outside growers, as the oak, for example ; indeed all trees of the U. 

 S. and of all northern latitudes, except the palms of the south. The 

 2d division of this class is composed of endogenous plants, or inside 

 growers, as the palm, lily, and iris ; they, having no need of bark or 

 external coveringj as they grow internally. Their substance or struc- 

 ture is confused, while that of exogenous plants is distinct and in reg- 

 ular annual deposites from the pith or centre outward, as will be seen 

 by examining any of our trees or their branches, when divided cross- 

 wise. These last have seeds with 2 lobes, are propagated by such, 

 and hence are all called dicotyledonous, while the former, or endoge- 

 nous plants, have single-lobed seeds and are monocotyledonous. 



Again the exogenous plants are divided into two tribes called angio- 

 spermia, and gymnospermia, the first denoting that the seeds are en- 

 closed in a pericarp, and the 2d, that they are naked, or destitute of a 

 pericarp. The endogenous are also divided into two tribes, the first 

 being called Petaloidce, including all plants of the class (all, in fine, 

 with 1 cotyledon, except grasses, and sedges) which have a calyx and 

 corolla in 3 or 6 dvisions ; or if these are absent, then the stamens 

 and pistils are naked. The 2d tribe is called glumaca ; such plants 

 of the class as have flowers with no true calyx nor corolla, but which 

 are enveloped in imbricated bracta, as all the grasses and sedge tribe. 

 There are also 3 sections in this class called Filicoidee, Muscoidece, 

 and Jtphylla. The 1st are such plants as have a distinct axis and 

 vascular system, as ferns, club-mosses, and horse-tail ; 2d such as 

 have a distinct axis, but not a vascular system, as musci, (mosses,) and 

 hepaticae, (liverworts,) and the 3d have no distinct axis nor vascular 

 system, as the fungi (mushrooms) Algae (flags.) 



Sub-class 1. Exogenous or dicotyledonous plants. Tribe Jlngiospermce, 

 2 seed-lobes inclosed in a pod, shell or coat, as pea, chestnut, etc. 

 The flowers of this tribe are polypetalous, (many petalled,) with calyx 

 and corolla, as crow-foot ; apetalous, (without petals,) with calyx, but 

 no corolla ; achlamydeous, (no calyx, or corolla,) as birch, willow, etc ; 

 monopetalous, with a single petal, as trumpet-flower, morning-glory. 



Tribe 2, Gymnospermce, seeds without a pericarp, and plants with- 

 out a stigma or pistil. The tribe is divided into Conniferce. (fir tribe,) 

 as pines, juniper, etc., and Cycadea, as cycas, zamia, etc. 



Sub-class 2, endogenous or monocotyledonous plants. Plants of this 

 class are intermediate between those of the 1st, which are of the 

 highest order of development, and the cryptogamous plants which are 

 of the lowest. Their character is indicated by their leaf when held 

 up to the light, these leaves being traversed with veins, showing that its 

 seeds are dicotyledonous, as plum, apple, radish, etc. ; the leaves are 

 also articulated or jointed with the stem. If veins of another leaf, 



