12. THE LEAF. 37 



ternate. This segmentation may be repeated in the leaflets, when the 

 leaf is said to be Alternate, triternate, etc. On comparing Fig. 23 B and F, 

 the close relation between pinnate and palmate leaves becomes apparent. 

 A ternate leaf is usually considered to belong to the palmate type, but it 

 might almost equally well be regarded as an imparipinnate unijugate 

 leaf. 



Occasionally the margin of the lamina bears outgrowths which 

 are not connected with branching, but are of the nature of 

 emergences, as in the Cherry Laurel, Naias, various Conifers, etc.. 



A number of terms are used in Descriptive Botany for the purpose of 

 precisely describing the various parts of plants. The more important of 

 these terms, and those the meaning of which is not obvious, will now be 

 denned. 



(1) The Outline of bilateral bodies, such as the lamina of the leaf, but 

 of multilateral bodies, such as fruits, as well, is said to be linear when 

 the two margins run nearly parallel to each other ; e.g. the leaves of most 

 Grasses. If the margins are curved and intersect at each end at aoi 

 angle, the outline is said to be lanceolate or elliptical, accordingly as the 

 long axis is many times longer than, or only twice as long as, the 

 transverse axis. If the two curved margins round off at each end, then 

 the terms oblong and oval are to be substituted for the two preceding. 



If the longest transverse diameter lies relatively near to the base, then 

 the outline is said to be ovate ; if relatively near to the apex, obovate. 



(2) The Apex may be either acute or obtuse ; when it is long drawn out 

 it is said to be acuminate ; when there is a sharp projecting point, it is 

 said to be mucronate (Fig. 23 F) 5 truncate, when it is, as it were, cut short 

 across (Fig. 23 Z>) ; emarginate, when there is a depression in the obtuse 

 apex ; obcordate, when the apical depression is deep. 



(3) The Base may be described by many of the preceding terms, but 

 the following are especially applied to it: it is cordate when it is deeply 

 indented in the median line ; sagittate, when the lobes on each side of the 

 indentation are angular and diverge backwards ; hastate, when the lobes 

 diverge outwards. 



(4) The Margin is said to be entire when it does not present any de- 

 pressions or prominences ; when the prominences are slight and rounded, 

 the margin is said to be crenate ; dentate or toothed, when the prominences 

 are pointed and stand straight outwards ; serrate, when the pointed 

 prominences slant forward. 



If the incisions in the margin are deep, the part, a leaf-blade for 

 instance, or a gamosepalous calyx, is said to be lobed when the incisions 

 do not extend to the middle ; if they extend to the middle, it is said 

 to be partite; and dissected when they extend nearly to the base (Fig. 23 C). 



The segmentation of the lamina takes place in some Monocotyledons 

 (Palms) in an altogether different manner from that described above. 

 The lamina is at first entire, but it becomes divided by the dying away 

 of strips of tissue. 



