66 
PLANT MORPHOLOGY. 
as parallel-veined leaves, and are characteristic of mono- 
cotyledons ; and the latter as reticulately veined leaves, 
distinguishing the dicotyledons. Reticulately veined 
leaves may be further subdivided into palmately veined, 
as in geranium or podophyllum, where the secondary 
veins arise from the base of the midrib and diverge to 
the periphery of the leaf; and feather-veined or pin- 
nately veined, as in chestnut, where the secondary veins 
arise from the midrib like the plumes on the shaft of a 
feather. 
(d) FORMS OF LEAVES. 
The leaves of plants exhibit an almost innumerable 
variety of forms; even on the same plant there are not 
infrequently several forms, as in Viola tricolor and sas- 
safras. Many of the terms used in ordinary language 
in describing the forms of objects are applied here 
also, as linear, lanceolate, oblong, elliptical, spatulate 
or wedge-shaped, etc. 
Apex. — A number of descriptive terms are employed 
in describing the apex of the lamina, as acute, when 
the form is that of an acute angle ; obtuse, when the 
angle is blunt; acuminate, when the angle is pro- 
longed ; truncate, when the end of the leaf appears to 
be cut off; retuse, when it is slightly notched at the 
apex ; obcordate, when the notch is pronounced ; emar- 
ginate, when the degree of notching is between retuse 
and obcordate. Sometimes the apex appears like the 
continuation of the midrib, when it is termed cuspidate 
or mucronate. 
Base. — Some of the terms used in describing the 
general outline, as well as the apex of the leaf, are also 
applied to the base, as obtuse, truncate, cordate, reni- 
form, etc. Other terms, however, especially apply to 
the base, as cuneate or wedge-shaped ; connate-perfoli- 
ate, when opposite leaves are connected at the base and 
