122 THE OPEN BOOK OF NATURE 
network in the blade, they are reticulated. Leaves 
are simple when they consist of one piece ; compound 
when they are divided into leaflets, as in the Clover 
or Horse-chestnut. 
Leaves without stalks are called sessile—i.e., 
sitting. A leaf of one stalk bearing three leaflets is 
ternate ; if it has five leaflets it is quinate. 
Radical leaves spring immediately from the root. 
Stem-leaves are opposite, alternate, or whorled. 
Whorled leaves grow in whorls or circles round the 
stem. 
When leaflets grow on opposite sides of a stalk, 
as in the rose, they are pinnate (penna=a feather). 
Pinnate leaves having an equal number of leaflets 
on each side of the midrib are paripinnate. When 
there is an odd leaflet at the end, as in the Rose, the — 
leaf is called imparipinnate. Pinnate leaves are 
often twice divided in a pinnate manner, then they 
are bipinnate. If the divisions are again divided 
pinnately they are tripinnate. 
Simple leaves are often lobed. Some lobes are 
deeply cut. A leaf having five or more narrow lobes 
joined near the stalk is palmate (hand-shaped). A 
leaf may be three, five, or seven lobed. Leaves 
lobed after the manner of pinnate leaves, but not 
divided into actual leaflets, are pinnatifid (cleft like 
a feather). 
A peliate (pelia=a buckler) leaf has its stalk, or 
petiole, attached at or near its centre. Example: 
Nasturtium. 
If the stalk passes through the leaf it is perfoliate 
(per=through, and foliwn=a leaf). Examples: 
Thorow-wax, Hare’s-ear Cabbage. 
