ELEMENTS OF BOTANY. xiii 



49. When the flowers arise from the axil of the ordinaiy leaves of tlie stem, 

 they arc said to be axillary ; but ofteiicr, they are disposed in a more or less 

 obvious cluster, each arising from the axil of a greatly reduced leaf, or Bract. 



50. The stalk of a solitary flower, or of a cluster of flowers, is termed the 

 Peduncle ; or, when it proceeds from tlie root, a Scape ; and that of each indi- 

 vidual of a cluster is called a Pedicel. The main axis of a cluster, or that 

 portion of the common peduncle which bears the flowers, is called tlie liachis. 



51. The indefinite inflorescence includes the Sijike, Ament, Spadix, Raceme, 

 Corymb, Umbel, Head, and Panicle ; the definite, the Cyme and its modifications. 



52. The Spike consists of a more or less elongated rachis, with the flowers 

 sessile, or nearly so, in the axils of the bracts. 



53. The Ament, or Catkin, is the scaly deciduous spike of the Pine and 

 WUlow. 



54. The Spadix is a spike with the flowers borne on a thick and fleshy rachis. 

 It is naked, as in the Golden-club, or enclosed in a hood, called the Spathe, as in 

 the Indian Turnip. 



55. The Raceme presents the elongated rachis of the spike, but the flowers 

 are raised on pedicels. 



56. The Corymb is a short raceme, with the lower pedicels elongated, so as to 

 bring their flowers to the same level as the upper ones. 



57. The Umbel is a modification of the raceme, but with the rachis so much 

 contracted, that the pedicels (rays) apparently spring from a common centre. 

 When the umbel is compound, the partial umbels are termed Umbellets. 



58. A Head is an umbel with sessile flowers. The crowded bracts of this and 

 the preceding are collectively termed the Involucre, and those of the umbellets, 

 the Involucel. 



59. When the pedicels of a raceme or corymb are transformed into branches, 

 either simple or successively divided, the inflorescence becomes a Panicle. 



60. When the further growth of the axis is arrested by a single terminal 

 flower, and from the axils below branches are developed, each terminated by a 

 flower, and bearing branches in the same manner, the inflorescence is said to be 

 cymose or centrifugal. But it presents several peculiar forms, occasioned either 

 by the imperfect development, or by the entire suppression of some of its parts. 

 Some, as the true Cyme, are short and expanded ; others are elongated, like the 

 spike or raceme. In all, the flowers expand successively from the summit, 

 downward, or from the centre, outward. 



61. The Flower consists, commonly, of one or more whorls of leaves, called 

 the Floral Envelopes, — of which the outer one is termed the Calyx, and the inner 

 one the Corolla, — an inner whorl of thread-like organs, called the Stamens, and 

 one or more central organs, called the Pistils. These are inserted on the apex 

 of the axis, which here takes the name of Torus, or Receptacle. 



62. The Floral Envelopes are' sometimes wanting ; but the stamens and pis- 

 tils, being the fertilizing organs, are, in all perfect flowers, always present. 



63. The Calyx is composed of leaves (Sepals), usually of a greenish color, 

 which are distinct, or united by their margins. When the floral envelopes con- 

 sist of a single whorl onlv, it is always a calyx. 



' b 



