stemmed (example, a Palm). Besides which, the following characters, although 

 far less absolute, deserve attention : Exogense in germination protrude their 

 radicle at once ; while in Endogense it is contained within the substance of 

 the embryo, through which it ultimately bursts : Exogense have two or more 

 cotyledons; Endogense have but one. Exogenae approach Endogense by Grasses 

 and Asphodelese, which branch like themselves, and by Smilacese and Aroidese, 

 Avhich have foliage resembling that of many Exogense. Tlie number of divi- 

 sions of their flower is hardly ever ternary, but usually some multiple of two, 

 or four, or five. In this country the trees and shrubs, and larger herbaceous 

 plants, are nearly all Exogenous; while our native Endogense are chiefly 

 confined to grasses, sedges, orchises, bulbs, and submerged water-plants. 



Exogenous plants have their seeds either enclosed in a pericarpium {An- 

 giospermce), or naked {GyvmospermcB). 



TRIBE I. ANGIOSPERMvE. 



These comprehend all Exogenous plants the seeds of which are enclosed 

 within a pod, or shell, or coat proceeding from the ovarium ; in short, the 

 whole of that sub-class, with the exception of Cycadeae and Coniferse. They 

 are all fecundated through the medium of a stigma and style ; while Gymno- 

 spermag, having no stigma or style, have the vivifying influence of the pollen 

 communicated directly to the seed through its foramen. The latter must not 

 be confounded with the naked-seeded plants of Linnseus, which all belong to 

 Angiospermse, and which are either minute fruits, or divisions of a compound 

 pistillum : they are always known by the presence of a style and stigma. 



This tribe is divided into Polypetalous, Apetalous, Achlamydeous, and 

 Monopetalous plants ; of which the first three may be considered extremely 

 artificial divisions if 'taken separately, but forming together a tolerably 

 natural whole ; while the Monopetalous division is also, in a great measure, 

 natural. I shall therefore treat of Exogense under two heads only. 



1. POLYPETALOUS, APETALOUS, AND ACHLAMYDEOUS 



PLANTS. 



Polypetalous plants have both a calyx and corolla ; Apetalous plants 

 have only a calyx, without a corolla ; and Achlamydeous ones have neither: 

 but these distinctions are merely artificial, and even in that point of view 

 very imperfect, — Polypetalous orders constantly containing Apetalous genera, 

 and orders with the strictest natural affinity diftering in the absence or pre- 

 sence of floral envelopes. Even Decandolle himself suggests {Mcmoire sur 

 les Combretacces, p. 2), that it is doubtful whether the division of Mono- 

 chlamydese (which are the same as Apetalse) is not entirely artificial. 



While, therefore, I have availed myself of these differences in framing the 

 diagnoses, and forming the artificial table, I have, in the following detailed 

 account of the orders, thrown the three divisions together, so that the 

 mutual relations of the orders may be obscured as little as possible. In 

 using the artificial tables, if an Apetalous plant cannot be referred to any 

 order of Apetalse, its place should be sought for among Polypetalse, to some 

 order of which it will probably be found to be an exception : it is very little 

 likely to belong to Monopetalsc, the Apetalous genera of which are extremely 

 rare. There are no plants of Achlamydevp with a calyx except some Be- 

 tulinea:, the flowers of which have a membranous veinless covering, of the 

 nature of a calyx. 



These orders pass into Monopetalne through Caprifoliaccce, among which 

 Hedera is nearly allied to Araliaceic, and through Salicariuc which are very 

 near Labiatse, Meliacege which touch upon Styraceoe, and Passiflorese which 

 stand next to Cucurbitacccc. 



