July 



1918 



HORTICULTUEE 



Letteks From an Old to a Young Gardener 



On Hybridizing and Crossing the French Iris 



Description of the Parts of an Iris 

 Flower Used in Hybridizing 



^\'e iit'ed know ui)ly a few terms to undei- 

 :^ta)i(l in a description, tlxise parts of a flower 

 used in crossing, luit for tlie same reason a 

 physician should kiniw anatciniy a gardener 

 should know the anatomy of plants. The 

 moie we know of plant physiology the hetter. 

 At the end of this letter two or three inter- 

 esting hooks to get ac(|uainted with will be 

 given as an appendix. Tlie outer parts of an 

 iris flower are called the [lerianth. This con- 

 sists of si.x segments. Three are upright or 

 incurved. They are called the erect seg- 

 ments of the perianth. Three are horizontal 

 or hanging down. These are named the 

 drooping segments of the perianth. Within 

 the floral envelope thus formed are the male 

 organs and parts of the female. The pollen, 

 usually called the male agent, is contained in 

 the anthers, indicated in the figures Ly the 

 letter A. Those |uiits of what are usiuilly 

 called the female organs, which are enclosed 

 in the perianth, are the stigmas, marked in 

 the pictures hy the letter S. Each stigma 

 has two lips, shown by the letter L. 



The flower in figure 2 has had the droop- 

 ing segments of the perianth removed, re- 

 vealing the three anthers A, and directly 



back of them, 

 other jiart of 

 l)ridizer is the 

 marked in the cuts. 



Iris Athena. 

 Figure 1 



the three stigmas, S. The only 



inunediate importance to the hy- 



ovary with its ovules. The former is 



It is generally green, and not 



a. part of what we usually think of as the flower. The 

 ovary has three divisions, each connected with a stigma. 

 The terms given are the old ones, but perfectly legiti- 

 mate. To have used the modern ones would have com- 

 plicated the description. They are long and would have 

 needed mierophotographs to explain them. The pollen 

 grains strictly speaking, are not the male organs, or the 

 ovules the female, they are only groups of cells con- 

 taining them. 



For the purpose of crossing we may look upon an 

 iris flower as an apartment house having three suites, 

 each occupied hy one couple. If we wish the seed pod 

 to be symmetrical, like those shown in Figure 9, we 

 must be sure each family has about the same number 

 of children. To ensure this we must apply the pollen 

 to each stigma. The seed pods shown came from a 

 plant, one of whose flowers is seen in Figure 1. They 

 show good pollination and fertilization, as each divis- 

 ion of one pod contained fifty jdump seeds. Figure 3 



