ABNORMALITIES IN INFLORESCENCE OF SPIRAEA VANHOUTTEI 63 1 
bution of numbers of abnormal pedicels per inflorescence in groups of 
inflorescence with similar number of pedicels is skew, just as it is in 
the series as a whole. 
The second peculiarity of the distribution of abnormality in the 
inflorescences of this species is to be seen in the frequency of numbers 
of flowers per pedicel. This is excellently shown for a combined 
series of countings made from 18 shrubs in 1909 and from three large 
individual plants examined in 1913. These frequencies, reduced to a 
percentage basis, are represented graphically in diagram 3.^ 
Table IV 
Bimodal Distribution of Number of Flowers per Pedicel in the Abnormal Inflorescences 
of Individual Plants 
Plant 
Number of Flowers Produced by Abnormal Pedicels 
Number 
J 
Total 
2 
3 
4 
5 
6 
7 
8 
9 
II 
12 
13 
14 
15 
lb 
17 
I 
27 
5 
7 
9 
II 
15 
31 
31 
59 
40 
17 
8 
I 
261 
2 
I 
3 
2 
I 
3 
5 
3 
2 
20 
3 
II 
6 
9 
6 
8 
19 
8 
2 
69 
4 
26 
15 
II 
6 
8 
6 
6 
16 
9 
6 
2 
III 
5 
8 
4 
8 
5 
4 
10 
12 
24 
13 
7 
3 
98 
6 
22 
7 
10 
4 
6 
12 
10 
16 
19 
12 
6 
I 
125 
7 
12 
9 
7 
10 
12 
7 
15 
13 
8 
3 
96 
8 
31 
25 
15 
II 
7 
14 
12 
31 
36 
53 
62 
55 
27 
9 
I 
389 
9 
20 
6 
14 
7 
9 
10 
8 
15 
10 
8 
3 
no 
10 
8 
3 
2 
I 
I 
4 
6 
6 
4 
35 
II 
21 
II 
5 
5 
3 
4 
21 
22 
15 
9 
3 
119 
12 
3 
3 
3 
4 
13 
8 
3 
37 
13 
41 
31 
16 
14 
16 
13 
31 
50 
47 
28 
21 
4 
I 
313 
14 
19 
10 
9 
7 
3 
8 
10 
12 
18 
26 
II 
3 
136 
15 
34 
10 
7 
10 
9 
9 
22 
35 
42 
41 
26 
6 
2 
253 
16 
23 
12 
II 
9 
8 
25 
32 
33 
21 
7 
4 
185 
17 
22 
7 
6 
6 
6 
8 
II 
14 
15 
6 
6 
3 
I 
III 
18 
35 
6 
9 
9 
8 
8 
26 
47 
81 
61 
28 
5 
I 
324 
Total. . 
364 
173 
149 
121 
124 
188 
274 
373 
399 
307 
192 
85 
32 
9 
I 
I 
2,792 
In all four series there is a major mode on 8, 9 or 10 flowers per 
pedicel and a secondary mode on two flowers per pedicel. 
This species adds, therefore, one other to the series of dimorphic 
characters, which have been reviewed elsewhere.^ 
That the bimodal condition for the 1909 series is not due to the 
mixing of inflorescence from a series of shrubs, some of which have a 
^ A few synanthous flowers have been included among the two-flowered pedicels. 
9 Harris, J. Arthur, A Bimodal Variation Polygon in Syndesmon thalectroides 
and its Morphological Significance, Amer. Nat. 44: 19-30. 1910. 
