APETALiE 345 



69. The Nettle Group (Summary). 

 {Introductory Volume^ p. 176.) 



Of the order Urticacese there are four British 

 genera — the Elm, Nettles, Pellitory-of-the-Wall, 

 Hop — which are arranged in three tribes: Ulmeas, 

 with flowers bisexual as a rule, a three- to eight-lobed 

 or -partite perianth. The filaments are slender, 

 straight in bud. The ovary is one- to two-celled. The 

 ovules are pendulous. There is no endosperm, and 

 the embryo is straight. In the Urticese the flowers 

 are unisexual. The perianth in the male is four- to 

 five partite, in the female tubular or four- to five- 

 cleft. The filaments are bent inwards in bud with 

 the anthers reversed. The ovary is one-celled. The 

 style is simple or absent. The ovule is erect and 

 orthotropous. The albumen is fleshy or absent. 

 The embryo is straight. This includes Urtica and 

 Parietaria. In the Cannabinese the plants are 

 dioecious, the males in a panicle, the females in a 

 cluster or spike. The perianth of the male is five- 

 partite, that of the female one scale-like sepal. The 

 anther-stalks are straight in bud. The ovary is one- 

 celled. There are two st5des, and the ovule is 

 pendulous. The albumen is fleshy ; the embryo is 

 curved ; in the Hop the stem is twining ; the embryo 

 is spiral. 



Hemp is sometimes found in this country. 



The Elms are placed in a separate order, Ulmaceae, 

 by some, and Humulus in another order, Canna- 



