638 ' PART III. THE CLASSIFICATION OF PLANTS. 



(see Fig. 321) : stamens ten, rarely fewer, frequently very numerous, free 

 (Fig. 437), usually much longer than the perianth : legume sometimes divided 

 by transverse septa : seed rarely albuminous : flowers usually grouped in spikes 

 or capitula. 



Mimosa pudica, the Sensitive Plant, has irritable leaves. Species of Acacia 

 are numerous ia Africa, Asia, and Australia. In the Australian species the 

 leaves are represented by flattened petioles (phyllodes, p. 49) which are extended 

 in the median plane. 



Order 3. Platanacej]. Trees, with diclinous flowers in 

 capitula borne laterally on pendulous branches; flower perigynous, 

 perianth differentiated into calyx and corolla, 3-4-merous : andrcB- 

 cium of but few stamens : gynasceum apocarpous ; each ovary 

 contains usually a single ovule, and developes into a caryopsis ; seed 

 suspended, orthotropous, with but little endosperm: leaves 



scattered, with persistent sheathing 



stipules. 



Platanus occidentalis, from North America, 

 with three-lobed leaves, and P. orientalis, from 

 the East, with usually five-lobed leaves, which 

 are often cuneiform at the base, are frequently 

 cultivated (especially the former). The smooth 

 bark, which is shed in flakes, is very character- 

 istic (p. 212). The Plane may be at once dis- 

 tinguished from the Maples, which resemble it a 

 good deal in the form of the leaf, by the scattered 

 Fig. 438. ? flower of Platanus arrangement of the leaves, 

 (mag.). 



Cohort V. Saxifragales. Flowers generally ambisporangiate 

 and actinomorphic ; hypogynous, perigynous or epigynous : ea- 

 cyclic ; stamens usually in two whorls, with obdiplostemony ; 

 ovary generally syncarpous, multilocular, with more than one style 

 or stigma ; ovnles usually numerous in each loculus ; seed with 

 or without endosperm. 



Order 1. SAXiFKAGACFiE. Flowers usually 4-5-merous, epigy- 

 nous or perigynous, completely actinomorphic only when there are 

 five carpels : stamens usually in two whorls ; carpels less numer- 

 ous, usually connate below and free above ; seeds numerous, 

 containing endosperm. 



Tribe 1. Saxifragece. Flowers perigynous or epigynous, regular, but 

 generally zygomorphic in consequence of oligomery in the gynaeceum : petals 

 with imbricate aestivation, sometimes suppressed : two whorls of stamens, but 

 one or other of the whorls is suppressed in some genera and species : carpels 



