586 



PART III. THE CLASSIFICATION OF PLANTS. 



Poplar or Abele. with five-lobed leaves on the elongated shoots, which are white 

 and woolly beneath; and P. Tremula, the Aspen, with sinuate-serrate leaves, 

 glabrous beneath, which are versatile on the long slender and compressed 

 petiole, and which are therefore very readily set in motion by the wind. In the 

 Section Aigeiros, the young shoots and the buds are viscid and glabrous ; the 

 bracts are glabrous, and the number of stamens is usually from 15-30 ; the 

 stigmata are entire or shortly lobed : to this section belong P. nigra, the Black 

 Poplar, and a variety with erect branches, the Lombardy Poplar ; of the latter, 

 only (J individuals are usually cultivated. In the Section Tacamahaca, the 

 young shoots and bnds are viscid ; the leaves grey below, with compressed 

 petioles : and the stamens 20-30 : to this section belongs P. balsamifera of 

 North America and Siberia. 



Cohort. IV. Proteales. Characters, those of the natural order. 



Order 1. PROTEACEJ:. Affinities doubtful. Flowers ambispor- 

 angiate ; the very short stamens are superposed on the four seg- 

 ments of the simple perianth, and are adnate to them (Fig. 391 B) : 



FIG. 391. -Flower of Manglesia glalrata. A Before Fro. 392. Flower of Cheno- 

 opening. B Open : p segment of the perianth ; a podium (enlarged) : fc peri- 

 anther; n stigma. C Ovary (below) in longitudinal atith ; a stamens; / ovary; 

 section ; gp gyuophore. D Transverse section of n stigma, 

 the ovary. E Ripe fruit. (After Sachs.) 



when the flower opens, the tube of the perianth often becomes still 

 more deeply cleft : the superior monomerous ovary is usually 

 borne upon a prolongation of the axis (Fig. 391 C, gp) : ovules one 

 or more, ascending : seeds without endosperm. 



Protea, Grevillea, Manglesia, and others occur mostly in South Africa and in 

 Australia. 



Cohort Y. Chenopodiales. Flowers usually am bisporangiatej 

 perianth sepaloid or petaloid : ovary monomerous or polymerous ; 

 ovule usually solitary ; embryo coiled or curved : ripe seed con- 

 tains perisperm, but no endosperm. 



