The Natural System of Botany. 301 



vivutn, House-leek, and Sedum, Stone-crop, are familiar to 

 every one. The parts of the flower are subject to remarkable 

 variations. The sepals vary in number from three to twenty; 

 the petals equal the sepals in number, and they sometimes 

 form a monopetalous corolla. The stamens are either equal in 

 number to the petals, and alternate with them, or twice as 

 inan y. The number of carpels is the same as that of the 

 petals. Each contains several ovules, arranged in two lines. 



The common House-leek, (Sempervivum tectarum) is a na- 

 tive of Britain, and is remarkable for often bearing ovules on 

 its anthers, instead of pollen. So tenacious of life are some of 

 these plants, that even when submitted to great pressure, and a 

 high temperature, for the purpose of drying them for the Her- 

 barium, they will continue to grow and send out long shoots. 



Order, Saxifragaces — The Saxifrage Tribe. 



Many of this order are alpine plants, inhabiting cold and 

 mountainous countries, while others are among the most com- 

 monly cultivated garden flowers. Of the former are the low 

 I species of Saxifrage, which in New England expand their neat 

 white flowers among the rocks in early spring, and of the lat- 

 ter are the Hydrangea, with its many varieties, and the Phila- 

 delphus, Syringn, or Mock Orange. The sepals of these plants 

 are four or five, more or less adherent. Petals of an equal 

 number, inserted between the lobes of the calyx. Stamens 

 from five to ten. The ovary consists of from two to five car- 

 pels, united at the base, and distinct above. The fruit is 

 generally one or two-celled, and many-seeded. The order is 

 divided by some botanists into four sub-orders, Saxifrages ; 



ESCALLONIS ; Hi'DRAXGE^E ; PHILADELPHIA. 



Order, Umbelliferje — The Umbelliferous Tribe. 



This is an order of great extent and importance, and the 

 I plants which belong to it are very readily distinguished by a 

 most obvious peculiarity. This consists in their manner of in- 

 florescence, which may be observed in a specimen of any com- 

 mon species, such as Parsley, Fennel, or Parsnip. The flower- 



