XU INTUODrCTION. 



35. A complete loaf comprises the Blade, the Slalk, and a pair of Stipules ; 

 but tlicse three parts arc not always present in one leaf. 



36. The 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 ; and compound, when of two or more distinct pieces (leajids), which 

 separate by a joint. 



37. The Stalk, or Petiole, connects the blade with the stem. When it is 

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



38. Tiie Stipules are appendages of various fonns, 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 (Ochrea) around the 

 stem above. The stii)ules of a leaflet are called Stipels. 



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

 I'ieiuttion. 



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 (veinltts), which again unite to form a kind of network. 



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

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

 tervals lateral veins ; and the jxilmatehj veined or ribbed leaf, when it divides at 

 tiie ajx'x into three or more strong branches. 



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

 venation. 



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

 {sinuses) extend about half-way to the midrib, or continuation of the petiole; 

 and pinnateli/ 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 side of the common petiole. When this is terminated by a leaflet, the leaf 

 is said to be odd-jiinnate, or unequally pinnate, an<l when it is wanting, abruptly 

 pinnate. 



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

 when the incisions are directed ti/ward the base of tlie blade. When the divis- 

 ions consist of separate leaflets, it becomes pdlmalily compound. 



45. Floral leaves, or those from the axils of which the flowers are developed, 

 are called Bracts; and those wliich are borne on the flower-stalk, Braclhls. 



6. Tlic Flower. 



40. A Flower consists of those parts, or organs, wliidi arc concerned in the 

 proiluction of seed. Like the leaf, of which its \n\yU are a niodilication, it is 

 developed from an axillary or terminal bud. 



47. The manner in which tlio flowers are arranged on flic stem or brnmhes is 

 termed the Jnflorcsrcnre. 



4R. There are two modes- of inflorescence ; vi/,. the iml finite, or cnitil petal, 

 where the flowers all arise from axillary buds, the lowest or outermr)st ex|)and- 

 ing first, while the axis elon;:ates indefinitely from the terminal bud; and the 

 definite, or rrntrifuijnl, where the flowers arisi- from the fcrminiil Imd, first, of the 

 main nxiw, nnil Buceessivcly fnmi that of the branches. 



