8 



INTEODUCTORY. 



plant. "When the leaflets themselves have a stalk (Petiolule ) they are 

 petiolulate. Often the leaflets of a pinnate leaf themselves become com- 

 pound, when we have a doubly or twice-pinnate leaf ; this division may 

 be continued to produce thrice-pinnate, &c. 



The number of leaflets in a compound leaf is expressed hj pinnately 

 3-fohoIate, 5-folioIate, &c., or palmately 3-foholate, 5-foliolate, &c. 



Yery much divided leaves, especially if irregularly so, are called de- 

 compound. 



27. The point of attachment of tlie leaf to the stem is its insertion. 

 Those leaves which are inserted at or beneath the surface of the ground, 

 are called Radical- or Boot-leaves ; those along the ascending stem, cau- 

 line ; and those near the flower, Floral-leaves or Bracts. 



The insertion of the leaf is in three principal ways : when two arise 

 from each node or joint, they are opposite (Fig. 34) ; when there are 3 

 or more at each joint, they are whorled or verticillate (Fig. 114) ; and 

 alternate, when only one is produced at each node (Fig. 24). Alternate 

 leaves present a great variety in their arrangement. When one is pro- 

 duced above another on exactly opposite sides of the stem, they are 2- 

 ranked. When they are so placed that each is i the circumference of 

 the stem from the other, we have the S-ranked order, and so on for the 

 5-ranked and others. The subject of the arrangement of leaves, or Phyl- 

 lotaxy, as it is called, is one which presents much interest to the curious, 

 and will be found clearly explained in Gray's Botanical Text Book. 



28. When the bases of two opposite leaves grow together, appearing 

 as if the stem passed through them, they are connate-perfoliate ; when a 

 single leaf presents this appearance by the union of the lobes of its base 

 beyond the stem, it is called perfoliate. 



Pairs of opposite leaves crossing each other at right-angles are decus- 

 sate. 



Where several leaves are crowded together, so as to spring apparently 

 from the same point, they are clustered or fascicled. 



Leaves and other parts which fall soon after expanding, are fugacious 

 or caducous ; deciduous, when they fall at the close of the season ; per- 

 sistent, when they last the whole year or longer, 



29. The manner in which leaves are disposed in the bud is their verna- 

 tion or prefoliation. When each leaf is infolded lengthwise, it is condur 

 plicate ; plicate, when several times folded or plaited ; involute, when 

 the margins are rolled in ; revolute, when rolled backwards towards the 

 midrib ; convolute, when rolled up from one edge ; and circinate, when 

 spirally rolled from the apex downwards. 



30. Stipules (20) are not always present. In the Magnolia Family 

 their office seems to be to protect the bud, and they fall away early ; in 

 other cases they remain with the leaves. When the leaflets of a com- 

 pound leaf have stipular appendages, they are said to be stipellate. If 

 the stipules adhere by one edge to the petiole, they are adnate, as in tl-a 

 Clover (Fig. 74), and if they unite around the stem, they form a sheatli 

 or Ochrea, as is seen in Polygonums (Fig. 179). 



31. Organs of Eeproductiox consist of the flower, fruit and seed. 



