352 CHARACTERS OF CLASSES AND ORDERS. 



735. In the succeeding pages the natural orders will be grouped 

 under the following divisions : 



A. PHANEROGAMOUS, OB VASCULAR FLOWERING PLANTS. 

 Class I. Dicotyledones or Exogense. 



f Subclass 1 .Thalamiflorse, Petals distinct, ~| 



TV T.I., A* stamens hypogynous I Polypetalse of Jus- 



Dichlamydeie ' 2 Calyciflor Je ,:....?.Petal S distinct, f sieu. 



having calyx { stamens perigynous J 



and corolla. 3 Corolliflore) Petals un i t ed,< Monopetala; of 



I bearing the stamens / Jussieu. 



[ 4. Monochlamydese,.A calyx only,^ 



Having a sin- 1 or none I Apetalae and partly 



gle perianth, j a. Angiospermse, seeds in an ovary. [Diclines of Jussieu. 



6. Gymnospermae, seeds naked, j 



Class II. Monocotyledones or Endogense. 



Subclass 1. Dictyogense, Floral envelopes verticillate, leaves reticulated. 



2. PetaloideasorFloridffijFloral envelopes verticillate, leaves parallel- 

 veined. 



a. Hermaphrodite, ovary adherent. 



b. Hermaphrodite, ovary free. 



c. Unisexual, often achlamydeous. 



3. Glumacese, Floral envelopes imbricated, leaves parallel-veined. 



B. CRTPTOGAMOUS, OR CELLULAR FLOWERLESS PLANTS. 

 Class III. Acotyledones or Acrogenae. 



Subclass 1. .JDtheogamse or Cormogense Having vascular tissue. 



2. Amphigamae, Thallogense, or Cellulares, Entirely cellular. 



CHAPTER II. 



ARRANGEMENT AND CHARACTERS OF THE CLASSES 

 AND NATURAL ORDERS. 



SECTION I. PHANEROGAMOUS PLANTS. 

 CLASS I. DICOTYLEDONES AND EXOGEN.E, Juss. and DC. ACRAMPHIBRYA, Endl. 



736. This is the largest class in the vegetable kingdom. The plants 

 included under it have a cellular and vascular system, the latter con- 

 sisting partly of elastic spiral vessels (fig. 49). The stem is more or 

 less conical, and exhibits wood and true bark. The wood is exogenous, 

 i. e. increases by additions at the periphery, the hardest part being 

 internal (^[ 72, &c.) It is arranged in concentric circles. Pith exists 

 in the centre, and from it diverge medullary rays. The bark is separ- 



