MONOCOTYLEDONS. GRASSES. 



113 



1st. The existence of a single coty'Jedon in the seed, a circum- 

 stance which corresponds with a particular mode of germination. 

 2d. The existence of an endogenous stem, that is, a stem in 

 which the new fibres do not form concentric layers around the old, 

 but are arranged in scattered bundles. 



3d. The arrangement of the nerves of the leaves is almost al- 

 ways parallel ; as in Indian corn. 



4th. The existence of a single floral envelope, called perianth 

 m glume, which takes the place of calyx and corolla. 



45. These plants are also distinguished from the dicoty'ledons 

 by their aspect and by some other characters. We place in this 

 group the Grami'neoe, Palma'ceee, Asparagi'neae, Lilia'cese, Nar- 

 < 'ssa'cese, I'rideae, Orchi'dese, and several other natural families. 



46. The FAMILY OF GRAMI'NE^E Grasses 

 (Jigs. 136 and 139) belongs to the class of 

 monocoty'Iedons with stamens inserted below the 

 ovary, named for this reason, monohypogy'nia 

 (from the Greek, monos, single, upo, below, and 

 gune, woman, metaphorically, pistil, that is, hav- 

 ing the stamens fixed below the ovary). They are 

 for the most part herbaceous plants; their stem, 

 which is cylindrical and ordinarily hollow, pre- 

 sents at different points knots from which the 

 leaves arise; it is called a culm or straw. The 

 flowers are generally united in a spike or in 

 panicles (Jig. 137); their ovary is simple, and 

 the seed, sometimes naked, and sometimes fur- 

 nished with an envelope named 

 glume, is composed of an albu- 

 men or farinaceous perisperm, 

 having a lateral pit near its 

 base which lodges the embryo. 

 It is this perisperrn which ren- 

 ders many of these plants so 

 useful, by furnishing to man an 

 abundant and wholesome arti- 

 cle of food, flour, and meal, 

 &c. 



Fig. 136. 47. This family is composed 



DARNEL. of a great many genera, among 



Fig. 137 



DARNEL. 



Explanation of Fig. 137. A magnified flower of the darnel, Lo'liun 

 perenne, sometimes called ray-grass, &c. 



45. What natural families belong to the class of monocoty'Iedons ? 



46. What are the general characters of the grasses? What is a sulm * 



47. What genera belong to the family of Grami'neae ? 



19* 



