ORGANS OF GROWTH. 



SI 



with small rough hair points, feeling like sand paper; 

 scurfy, when covered with minute scurf, easily scraped off, 

 as in pineapple leaves ; lepidote, when covered with thin 

 scales, generally circular, lying flat on the surface, as in 

 Elceagnus and Deutzia, such being beautiful objects in 

 the microscope. Squamcd is a term for scales when long 

 and pointed, as common to ferns. 



Hairs are simple or sometimes forked ; in the Malpigh 

 family, the genus Incligofera (Indigo) and Grevillea 

 (Silk oak), they are attached by their centres, lying flat 

 on the surface of the leaf ; or in rays like a star, stellate, 

 as in the Mallow family ; in Solamim macranthum they 

 are raised above the surface and rayed, giving the idea 

 of a turnstile. When the hairs are on the margin of 

 the leaf only, it is called ciliate or fringed. 



Some leaves bear on their footstalk, margin, or disk, 

 small globular teat- or shield-like bodies, generally of a 

 pale, or brown colour, or even black as in St. John's- 

 wort j they are more or less firm or soft, often viscid, 

 and are called glands, sometimes sunk like little pores 

 or pits. The substance of many leaves is full of dots, 

 which are seen by holding a leaf of myrtle, orange, or 

 St. John's-wort between the eye and the light ; these are 

 called pellucid glands, or dots, and with the preceding, 

 are characteristic of several natural families. 



The position of leaves on the stem is either alternate, 

 opposite, or in luhorls of three or more, verticillate ; or 

 several issuing from, or near the same point, fasciculate. 



According to rule, the evolution of leaves is alternate, 

 the young unfolding leaf being always in advance, and 

 on one side of the one preceding it; the circuit of the 

 stem being completed by the evolution of every five 

 leaves, which may be readily seen by examination of 



