ILLINOIS NATURAL HISTORY SURVEY MANUAL 1 
B. REPRODUCTIVE 
Plants that propagate by means of their vegetative parts, 
such as by stolons as we have noted, have an asexual or vegetative 
means of reproduction. Plants that grow anew from seed have a 
sexual means of reproduction through the functioning of special- 
ized organs in the flower. 
Fig. 4—THE COMPLETE FLOWER. I.—Pistil; a, ovary; b, style; 
c, stigma. II.—Stamen; d, filament; e, anther, gross view; f, anther, 
cross-section. III.—Perianth; g, sepal; h, petal. 
THE FLOWER 
The complete flower.—A complete flower, fig. 4, consists 
of four kinds or sets of organs—pistils, stamens, petals and 
sepals. There is a type of flower in which these parts are 
spirally arranged around a central axis, but in all other flowers 
each set of organs makes up its own circle around the center of 
the flower and is called a whorl. In many flowers the organs are 
distinct and easily recognized; in others they are considerably 
modified. 
Pistils—The innermost whorl comprises one or more pistils. 
A pistil, fig. 4 I, usually has three parts. The enlarged portion 
at the base, a, is the ovary. Two or more individual pistils may 
occur, fused together so as to make the whole structure appear 
to be a single one having rounded projections, which mark the 
true number of pistils present. This is the compound pistil, and 
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