PLANT-STRUCTURE 



LEAF : leaves are simple and compound : 



Simple, when in one piece ; Fig. i. 



Compound, when in parts so distinct that each part looks like 

 a small but complete leaf ; the subdivisions are called leaflets ; 

 in a twice-compound leaf each leaflet is similarly subdivided ; 

 Fig. 2. 



COMPOUND LEAVES are of two sorts : pinnate and 



PALMATE. 



Pinnate has the leaflets along the stem, and at right angles 

 with it ; even- and odd-pinnate differ in regard to the end-leaflet ; 

 Fig. 2. 



Palmate has all the leaflets radiating from the apex of the 

 leaf-stem ; Fig. 3. 



ARRANGEMENT OF LEAVES ON BRANCH. Fig. 4 



Leaves are arranged in four ways : 



Alternate, when following along singly on branch (a). 



Opposite, when in pairs, on opposite sides of branch (b). 



Whokled, when three or more circle around stem at same 

 point (c). 



Indeterminate, when closely and irregularly crowded on 

 stem (d). 



Most leaves have longer or shorter stems, but some are stem- 

 less or sessile. 



FORMS OF SIMPLE LEAVES 



The general form of a leaf (Fig. 5) may be roundish (a), 

 oval (b), oblong (c), ovate (d), obovate (e), elliptical (f), arrow- 

 shaped (g), halberd-shaped (h), lance-shaped (i), linear (j), or 

 requiring some combination of these terms. 

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