INTRODUCTION TO BOTANY. Vll 



Leaves are, 



deltoid, equilateral-triangular, or shaped like a Greek A : when ap- 

 plied to the tooth of a calijx, the base of the triangle is sup- 

 posed to rest on the calyx tube. 



spathidate, when the broad part near the top is short, and the nar- 

 row, tapering part long, compared to a spatula, or flat ladle. _ 



ohlong (or broadly linear) when 2-4 times as long as broad, with 

 subparallel sides and blunt extremities ; 



ovate, when about twice as long as broad, broader below the middle, 

 or shaped like the longitudinal section of an egg ; obovate is 

 the same form reversed, the narrow end being at base. 



orbicular, or rotund, when approaching to a circular form. 



oval, or elliptical, when broadest in the middle, with curved sides, 

 like an ellipse, or oval. 



transversely oblong, or oblate, when conspicuously broader than long. 



rhornboidal, or rhomboid, when shaped like the mathematical figure 

 called a rhombus. 



falcate, shaped like a scj-the, curved with nearly parallel sides and a 

 sharp point. 



44. Intermediate forms are expressed by combining two terms. Thus, 

 a linear-lanceolate leaf is long and narrow, yet rather broader below the 

 middle and tapering to a point ; ovato-lanceolate is broad towards the base, 

 yet tapei-ing towards the apex, etc. 



45. The apex or summit of a leaf is, 



acute, OT pointed, when it is sharp, or forms an acute angle. 



obtuse, or blunt, when it forms an acute angle or oftener is rounded. 



acuminate, when suddenly narrowed near the top and then pro- 

 longed into an acumen, or projecting >»oi;^^, which may be acute 

 or obtuse, linear or tapering ; cuspidate is either synonjnnous 

 with acimiinate, or else used to express a more exaggerated 

 degree of acmnination, with a more sudden, sharper, and more 

 rigid point. 



truncate, when the end is cut off nearly square. 



retuse, when very obtuse or truncate, and slightly indented in the 

 middle; 



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

 the midiib. 



mucronate, when the midrib is produced beyond the apex in the 

 form of a small point ; mucronulate when it projects very little. 



aristate, when the point is long and fijie, like a bristle. 



46. The base of the leaf is liable to the same variations of form as the 

 apex, but the tenns commonly used are tapering or narrowed for acute and 

 acuminate ; rounded for obtuse ; and cordate for emarginate. But the term 

 cordiform, cordate, or heart-shaped leaf, is restricted to an ovate and acute 

 leaf, cordate at base, with rounded aimcles ; and obcordate to an obovate, 

 deeply emarginate or subbilobed leaf or leaflet, with rounded lobes. The 

 word auricle is more strictly applied to the prolonged base of sessile and 

 stem-clasping leaves. 



47. If the auricles (46) are pointed, the form is said to be sagittate when 

 the points are directed downwards, as in the head of an arrow ; hastate^ 

 when the points diverge horizontally, compared to a halbert. 



48. A reniform leaf is broader than long, very obtuse at apex, slightly 

 but broadly cordate at base, with rounded auricles, compared to a kidney. 



49. In a peltate leaf, the stalk, instead of proceeding fi-om the lower 

 edge of the blade, is attached to the under surface, often near the lower 

 edge, biit sonietunes in the very centre of the blade ; the nerves radiate 

 from the point of attachment of the petiole, or proper base of the leaf. It 



