so 



DOMESTIC BOTANY. 



The lobes may be either entire, dentate, serrate, or again 

 laciniatedj or yery much divided, multifid, as in parsley. 



Compound leaves consist of simple leaves produced 

 from a centre, or on a common footstalk, called rachis, 

 and each individual leaflet may be of any of the above 

 forms. The simplest compound leaf is conjugate, that 

 is, consisting of two leaves united, as in bean-caper and 

 "West Indian locust-tree ; it is trifoliate when three are 

 united, of which clover and the scarlet-runner are ex- 

 amples ; digitate, when more than three issue from the 

 same point, as the horse-chestnut; pinnate (winged), 

 when there are two or more pairs on a rachis, like the 

 pea, bean, and ash ; hipinnate, tripinnate, and sometimes 

 quadripinnate, is when the first rachis produces a second, 

 and the second a third, on which the leaflets are borne. 

 The sensitive and umbel plants, with others of the Mimosa 

 tribe, as also the hardy tree Gymnocladus canadensis and 

 Aralia arhorea are examples of the latter. 



Whatever may be the form of leaves, whether flat, 

 undulate, or curled in any way, they are either glabrous, 

 naked ; or pubescent, clothed. They are glabrous when 

 the skin or cuticle is quite destitute of hairs, or any ex- 

 traneous covering; they may nevertheless be covered 

 with small rough points, warty tubercules, or stifi" spines 

 on both surface and margin. They are pubescent when 

 clothed with hairs, wool, or scurf-like covering com- 

 mon to leaves and other organs of plants. This cover- 

 ing is very varied in character; setose, when the hairs 

 are stiff" like bristles ; pilose and villose, when the hairs 

 are long, soft, and silky ; lanuginose, when interwoven, 

 forming a woolly, felt-like web ; tomentose, when short, 

 and so close as to give colour (generally white) to the 

 leaf ; scabrous, when the surface of the leaf is covered 



