XU INTRODUCTION 



.15. A complete leaf comprises the Blade, the Stall-, and a pair of Stipules: 

 bat these three parts arc not always present in one leaf. 



36. Tin- Blade, Limb, or Lamina, is the expanded part, and presents a great 

 variety of forms. It is simple, when it consists of a single piece, however cut or 

 divided ; ami compound, when of two or more distinct pieces (Icujiels), which 

 separate by a joint. 



:57. The Stalk, or Fetiole, connects the blade with the stem. When it is 

 wanting, the leaf is said to he sessile. The stalk of a leaflet is called a Petiolule. 



38. The Stipules are appendages of various forms, placed one on each side at 

 the base of the petiole. They are separate, or else united with the petiole, or 

 with each other, when they occasionally form a sheath (Oc/irea) around the 

 stem ahove. The stipules of a leaflet are called Stipels. 



39. The manner in which the veins are distributed through the leaf is called 

 Vi nation. 



40. There are two modes of venation ; viz. parallel-veined, or nerved, when 

 several simple veins, or ribs, run parallel from the base of the blade to its apex ; 

 and reticulated, or netted-veined, when the veins divide into numerous primary and 

 secondary branches (ve inlets), which again unite to form a kind of network. 



41. The latter mode embraces both the pinnately veined, or feather-reined leaf, 

 where the petiole is continued through the middle of the blade, giving off at in- 

 tervals lateral veins; and the palmaidy veined ox ribbed leaf, when it divides at 

 the ajx-x into three or more strong branches. 



42. The manner in which leaves are divided corresponds with that of their 

 venation. 



43. A simple pinnately veined leaf becomes pinnatifid, when the incisions 

 (sinuses) extend about half-way to the mielrib, or continuation of the petiole ; 

 and pinnately divided, when they extend down to the midrib. A compound pin- 

 nately veined leaf is, of course, pinnate, with the separate leaflets arranged on 

 each Bide of the common petiole. When this is terminated by a leaflet, the leaf 

 is said to be odd-pmneite, or uncepially pinnate, and when it i> wanting, abruptly 



44. So, also, the palmately veined leaf becomes palmately cleft or divided, 

 when the incisions are directed toward the base of the blade. When the divis- 

 ions consist of separate leaflets, it becomes jxdmatdy compound. 



4."). Floral leaves, or those from the axils of which the flowers are developed, 

 are called Bract*', and those which are borne on the flower-stalk, BractietB. 



6. The Flower. 

 4 0. A Flower consists of those parts, or organs, which are concerned in the 

 production of geed. Like the leaf, of which its parts are a modification, it is 

 developed from an axillary or terminal bud. 



47. The maimer in which the flowers are arranged on the stem or branches is 

 termed the Inflon scene*. 



48. There are two modes of inflorescence; viz. the indefinite, or centripetal, 

 where the flowers all arise from axillary buds, the lowest or outermost expand- 

 ing first, while the axis elongates indefinitely from the terminal bud; and the 



, <>r centrifugal, where the flowers arise from the terminal hud, first, of the 

 main axis, and Buccessively from that of the branches. 



