

■m 



Vm INTRODUCTION. 



falcate, when curved like the blade of a scythe. 

 4G. Intermediate forms between any two of the above are expressed by combining 

 two terms. Thus, a linear-lanceolate leaf is long and narrow, yet broader below tlie 

 middle, and tapering to a point ; a Unear-ohlong one is scarcely narrow enough to be 

 called linear, yet too narrow to be strictly oblong, and does not conspicuously taper 

 either towards the summit or towards the base. 

 47. The apex or summit of a leaf is 



acitte OY pointed, when it forms an acute angle or tapers to a point. 



obtuse or blunt, when it forms a very obtuse angle, or more generally when it is 

 more or less rounded at the top. 



acttminate or cuspidate, when suddenly narrowed at the top, and then more or less 

 prolonged into an acumen ov point, which may be acute or obtuse, linear or tapering. 

 Some botanists make a slight difTerence between the acuminate and ciisp/idate apex, the 

 acumen being more distinct from the rest of the leaf in the latter case than in the 

 former ; but in general the two temis are used in the same sense, some preferring the 

 oiils and some the other. 



truncate, when the end is cut off square. 



reticse, when very obtuse or truncate, and slightly indented. 



emarginate or notched, when more decidedly indented at the end of the midrib ; 

 olcordate, if at the same time approaching the shape of a heart with its point do^^ n- 

 wards. 



mucronate^ when the midrib is produced beyond the apes in the forai of a small 

 point. 



aristate, when the point is fine like a hair. 

 4-8. The base of the leaf is liable to the same variations of form as the apex, but the 

 terms more commonly used are tapering or narrotved for acute and acuminate, rounded 



for obtuse, and cordate for emarginate. In all cases the petiole or point of attachment 

 prevent any such absolute termination at the base as at the apex. 



49. A leaf may be cordate at the base whatever be its length or breadth, or wliat- 

 ever the shape of the two lateral lobes, called auricles (or little ears), formed by tlie 

 indenture or notch, but the term cordiform or heart-shaped leaf is restricted to an 

 ovate and acute leaf, cordate at the base, with rounded auricles. The word auricles is 

 more particularly used as applied to sessile and stem-clasping leaves. 



50. If the auricles are pointed, the leaf is more particularly called auriculate ; it is 

 moreover said to be sagittate, when the points are directed downwards, compared to an 

 arrow-head; hastate, when the points diverge horizontally, compared to a halbcrt. 



51. A reniform leaf is broader than long, slightly but broadly cordate at the base, 

 with rounded auricles, compared to a kidney. 



52. In a peltate leaf, the stalky instead of proceeding from the lower edge of the 



blade, is attached to the under surface, usually near the lower edge, but sometimes in 



the very 'centre of the blade. The peltate leaf has usually several principal nerves 



radiating from the point of attachment, being, in fact, a cordate leaf, with the auricles 

 united. 



53. All these modifications of division and form in the leaf pass so gradually one 

 into the otlier that it ia often difficult to say which term is the most applicable— 

 whether the leaf be toothed or lobed, divided or compound, oblong or lanceolate, obtuse 

 or acute, etc. The choice of the most apt expression will depend on the skill of the 

 dcscriber. 



54. Leaves, w]ien solid, Stems, Fruits, Tubers, and other parts of plants, 

 when not flattened like ordinary leaves, are 



setaceous or capillary, when very slender like bristles or hairs. 



acicular^ when very slender, but stiff and pointed like needles! 



subulate, when rather thicker and finner Uke awls. 



linear, when at least four times as long as thick ; oblong, when from about two to 

 about four times as long as thick, the terms having the same sense as when applied to 

 flat surfaces. 



ovoid, when egg-shaped, with the broad end downwards, olovoid if the broad end 

 18 upwards ; these terms corresponding to ovate and ohovate shaj^es in flat surfaces. 



