356 MANUAL OF BOTANY 



Division of the Order and Illustrative Genera. — The Mesem- 

 bryanthacese may be divided into three sub-orders as follows : — 



Sub-order 1. Mesembeyanthe^. — Leaves opposite. Petals nu- 

 merous, conspicuous. Stamens numerous. Fruit capsidar, 

 dehiscent. — Illustrative Genera : — Mesembryanthemum, 

 Linn. ; Lewisia, Pursh. 



Sub-order 2. TsTEAGONiEa;. — Leaves alternate. Petals absent. 

 Stamens definite. Fruit woody and indehisoent. — Illustrative 

 Genera, : — Tetragonia, Linn. ; Aizoon, Linn. 



Sub-order 3. SesuviejE. — Leaves alternate. Petals absent. Sta- 

 mens definite. Fruit capsular, with transverse dehiscence. — 

 Illustrative Genera: — Sesuvium, Linn.; Cypselea, Turp. 



The last two sub-orders are sometimes placed in an order by 

 themselves, called Tetragoniacece, which is distinguished from 

 the Mesembryanthacese by having alternate leaves, no petals, 

 and definite stamens. The plants comprehended in the above 

 three sub-orders are, however, so nearly allied, that we have, 

 following Bentham and Hooker, placed them in one order as 

 above. TJie tribe MolluginecB of CaryopTiyllacece is also 

 placed in this order by Bentham and Hooher. 



Distribution and Numbers. — Natives exclusively of warm 

 and tropical regions. A large number are found at the Cape of 

 Good Hope. There are about 450 species. 



Properties and Uses. — Several are edible ; others yield an 

 abundance of soda when burned ; but generally the plants of the 

 order are of little importauce. 



Cohort 5. — Umbellales. 



Order 158. TJMBELLiFBEiE, the Umbelliferous Order. — Cha- 

 racter. — Herbs, shrubs, or very rarely small trees, with usually 

 hollow or rarely solid stems. Leaves alternate, generally amplexi- 

 caul, usually compound, or sometimes simple, and always exstipu- 

 late. Flowers generally in umbels, which are usually compound, 

 or sometimes simple ; rarely the flowers are in oapitula, with 

 or without an involucre ; the partial umbels or umbellules also 

 with or without an involucel. Calyx superior, the limb entire, 

 annular, or 5-toothed, or obsolete. Petals 5, usually inflexed at 

 the point, often unequal in size, inserted on the calyx outside 

 the disc which crowns the ovary ; mstivation imbricate, or rarely 

 valvate or induplicate. Stamens 5, inserted with the petals and 



