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Full text of "Seed production in apples"

ACES LIBRARY 



UNIVERSITY OF ILLINOIS 

Agricultural Experiment Station 



BULLETIN No. 203 



SEED PRODUCTION IN APPLES 



By CHARLES S. CRANDALL 




URBANA, ILLINOIS, AUGUST, 1917 



Summary of Bulletin No. 203 

1. In this bulletin is recorded the seed production of four groups of apples, 
a total of 31,972 fruits: large apples of orchard varieties, 12,912; small apples of 
orchard varieties, 8,500; crabs, 0,642; and hand-pollinated fruits, 3.918. 

2. Seed production in large apples exceeded that in small apples by 14.7 
percent, and was nearly twice that recorded for crab fruits; the average seed pro- 
duction was, for large apples, 8.27; for small apple?, 7.21; and for crab fruits, 
4.22. Page 188 

3. The minimum average seed content was 2.8, found in small fruits of 
Collins; the maximum average was 15.04, found in large fruits of Shockley. 

Page 188 

4. Approximately 12 percent of the large fruits of orchard varieties contained 
the assumed normal of 10 seeds; 69 percent averaged below this normal, and 
about 18 percent above normal. Page 189 

5. There was considerable variation in number of carpels; four orchard 
varieties held to the normal of five; all others showed departures from this normal. 
The range for large fruits was 4 to 8; for small fruits, 2 to 8. Page 191 

6. Parthenocarpic fruits were found more often among small fruits than 
among large fruits of orchard varieties. Page 190 

7. Percentages of ovules that developed as seeds were higher for groups 
of large apples than for small apples in twenty out of twenty-one varieties 
examined. Page 198 

8. A test of extremes in size for one variety confirmed results from all 
varieties and strengthened the evidence that large apples develop a larger pro- 
portion of the ovules they contain than do small apples. Page 199 

9. Crab fruits ranged in numbers of carpels from 2 to 12 and had a seed 
range of to 14. Pages 205, 207 

10. Production of ovules in excess of the expected normal occurred more 
frequently among orchard varieties than among crabs. Page 211 

11, Control of pollination exercised no marked influence on numbers of seeds 
developed. Page 213 



SEED PRODUCTION IN APPLES 

By CHAELES S. CR AND ALL, Chief in Plant Breeding in Horticulture 

INTRODUCTION 

Each normal fruit of the common apple is made up of five centrally 
located carpels, each carpel forming one cell. Each of the five cells 
contains two ovules attached near the base to the perpendicular 
placenta, which is on the inner side of the cell, and hence central in 
the fruit. When all ovules are fertilized and develop into seeds, the 
full complement is ten for each normal apple. 

Examination of a considerable number of apples brings *out the 
fact that departures from the normal number of seeds are common 
and of all degrees, from an entire absence of developed seeds to an 
increase to more than two and one-half times the normal. Naturally 
these variations in the performance of individuals and varieties in 
the matter of seed production suggest questions regarding the factors 
governing fertilization and seed development, the relation of seed for- 
mation to size of fruit, and the possibility of developing a definite 
system of association of orchard varieties that would make for increase 
in fruit production. The development of such a system could not 
be accomplished in one year, nor in several years; it would require 
long and patient effort, but there can be no doubt that valuable scien- 
tific as well as economic results would attend its successful accomplish- 
ment. It is not the intention to enlarge upon this idea in the present 
publication, but simply to place on record observations that have 
been made relative to the actual seed production of groups of apple 
varieties grown under usual orchard conditions. 

As a first step in a study of seed production in apples it is desirable 
to know something of the behavior of common orchard varieties in 
this regard. Do they live up to the possibilities in the matter of 
seed production ? Do they fall short of, or do they exceed a definite 
normal? Are there well-defined differences in seed production that 
may rank as varietal characteristics? How do varieties producing 
very large fruits, Wolf River for example, compare in seed production 
with varieties producing small fruits, such as Red June or Lady? 
Within a variety, does any definite relation exist between size of 
fruit and seed content? These are some of the questions that are 
suggested at the outset of the inquiry. 

OPINIONS REGARDING SEED PRODUCTION 

Horticultural literature, so far as consulted, yields little infor- 
mation concerning the questions here suggested. Seed production 
in apples appears to have been passed over. There are no records 

185 



186 Bulletin No. 203 [August, 

of extended investigation and only meager references to the perform- 
ance of this fruit in this particular. There do appear certain state- 
ments indicating common belief in a general principle that with 
seed-bearing plants, and especially with economic fruit plants, in 
which there is large development of edible parts, there is a correspond- 
ing diminution in seed-producing capacity; or, to state it more 
definitely, fruits with highly developed fleshy parts produce fewer 
seeds than do those fruits in which the fleshy parts are not enlarged. 

The development of seeds, the forming of the embryos, and the 
storing of food necessary for the young plants form an exhaustive 
process drawing heavily upon the resources of the plant. It is a per- 
fectly natural conclusion that the production of full complements of 
seeds and the storing of large quantities of edible fruit flesh are 
antagonistic and that large size and full seed production are not likely 
to be at a maximum in the same fruits. 

In discussing compensation and economy of growth, Darwin 1 makes 

this general statement: 

1 ' When the seeds in our fruits become atrophied, the fruit itself gains largely 
in size and quality. " 

Lindley says 2 : 

' ' Sterility is a common malady of cultivated plants, the finer varieties of fruit, 
and all double and highly cultivated flowers, being more frequently barren than 
fertile. This arises from several causes. The most common cause of sterility is 
an unnatural development of some organ in the vicinity of the seed, which attracts 
to itself the organizable matter that would otherwise be applicable to the support 
of the seed. Of this the Pear, the Pineapple, and the Plantain are illustrative 
instances. ' ' 

E. L. Sturtevant 3 affirms that small fruits contain more developed 
seeds than do large fruits. He writes as follows: 

''The better varieties of the apple usually contain some abortive seeds and 
are sometimes individually to be found seedless. As a rule, where there is a 
tendency to abortive seeds, the larger and finer the apple the greater the number 
of abortive seeds. Thus five Baldwin apples, weighing thirty ounces, had eleven 
plump and nine shriveled seeds; five others from the same barrel, and weighing 
seventeen ounces, furnished twenty-five plump and three abortive seeds." 

Dr. Sturtevant 's conclusion appears to be based upon examination 
of 145 apples representing thirty-five varieties. One variety, the Bald- 
win, was represented by sixty-seven apples; of the others, eighteen 
had one fruit each, four had two each, and twelve had numbers of 
fruits from three to eight. The average number of good seeds was 
5.67; the minimum number found was one each in Newtown Pippin 
and Gray Russet; the maximum was 12.75 in Northern Spy. The 
numbers of fruits examined, however, were too small, at least for all 
varieties except Baldwin, to serve as a good index of the seed-producing 
capacities of the varieties. 



Origin of Species, 6th ed., p. 139. 

2 Theory of Horticulture, Downing, 2d. ed. (1852), p. 170. 

"On Seedless Fruits, Mem. Torrey Bot. Club, 1, No. 4 (1890), p. 145. 



1917] Seed Production in Apples 187 

The authors quoted do not state the converse of the principle laid 
down, but each leaves the reader to infer that fruits not highly devel- 
oped, those in or near the wild state, while deficient in flesh, the part 
valuable to man, excel in seed production. 

Bailey 1 expresses a view contrary to that given by the writers 
quoted above. He says : 

"As a rule, the cultivated varieties of apples contaiu more seeds than the 
wild apples of Europe do. Forty specimens of the wild crab (Pyrus Malus) of 
central Europe produced an aggregate of two hundred fifty-six seeds, or an 
average of six and two-fifths seeds to each fruit. Forty Northern Spys contained 
four hundred eighty-one seeds, or an average of twelve and one-fortieth to the 
fruit. Normally, the apple should contain ten seeds, two to each carpel, but some 
of these Spys had fifteen seeds and one had eighteen. Yet some other varieties 
of apples contain fewer than the normal number, while some are almost entirely 
seedless. There is generally a slight increase in seed production as fruits develop 
away from the first type, especially if the fruits become larger. This is a natural 
consequence of the increase in size, tho it bears no constant ratio to this increase. " 

SEED-PRODUCTION RECORDS 

As a basis from which to judge the performance of apples and 
crabs in seed production when varieties are grown in mixed plantations 
and left open for undisturbed visitation by insects, records were taken 
from 28,054 individual apples. Thirty-two orchard varieties were 
represented by 21,412 fruits, and twenty-five species and varieties of 
the genus Malus were represented by 6,642 fruits. This latter is a 
strictly crab group ; none of the species or varieties have any economic 
value other than as ornamentals. They vary widely among themselves 
and represent several types, but all closely approximate the wild 
originals. 

With the exception of Garfield and Twenty Ounce, varieties repre- 
sented by small numbers of fruits very uniform in size, the fruits of 
each orchard variety were divided into two groups on the basis of size, 
a group of large apples and a group of small apples, in order to 
determine whether or not there is constant difference in seed produc- 
tion between groups thus separated. Transverse diameter was taken 
as the basis of division. In a few varieties all fruits 65 mm. or above 
in diameter were classed as large, all below that dimension as small. 
In most varieties, however, it was possible to leave a gap of from 
3 to 10 mm. between groups and in that way make them more distinct ; 
thus, in several varieties the maximum for the group of small apples 
was 70 mm., and the minimum for the group of large apples, 75 mm. 

In the crab group there prevailed such uniformity in the size of 
fruit within each species or variety that no division into size-groups 
was attempted. 

Records obtained from the fruits examined support the view that 
the more highly developed fruits, that is to say, such fruits as are 

^he Survival of the Unlike (1901), p. 253. 



188 Bulletin No. 203 [August, 

produced by varieties commonly grown in orchards, develop seeds in 
greater numbers than do the crab-like fruits of less highly developed 
forms of the genus Mains. A further fact developed from the records 
was that in nearly all the varieties, the fruits of which were divided 
into size-groups, the groups containing large apples produced more 
seeds than did the groups containing small apples. The differences 
between these three classes of fruits in average seed production are as 
follows : 

1. Average seeds to, the fruit for 12,912 apples of large size, representing 

thirty-two varieties, 8.27. 

2. Average seeds to the fruit for 8,500 apples of small size, representing 

thirty varieties, 7.21. 

3. Average seeds to the fruit for 6,642 apples, representing twenty-five crab- 

like forms of Malus, 4.22. 

Here the average for large orchard fruits exceeds the average for 
small orchard fruits by 14.7 percent, and is very nearly twice as 
great as for the crab-like forms. 

In each of the three groups for which average seed production is 
given there was a wide range between maximum and minimum seed 
production as exhibited by the different varieties and species. Thus, 
among the groups of large fruits, Collins was the least productive, 
the average for 261 fruits being 4.09 seeds, and Shockley the most 
productive, with an average for 177 fruits of 15.04 seeds. In the 
groups of small fruits, Collins was again the least productive, with 
an average for 150 apples of 2.8 seeds : the maximum here, as in the 
groups of large fruits, falls to Shockley, which, for 177 apples, had 
an average of 14.59 seeds. 

In the crab group the lowest in seed production was Malus fusca, 
with an average of 1.32 seeds to each fruit, but this species was repre- 
sented by so few fruits that this average is not regarded as depend- 
able for the species. The next lowest was Malus atrosan guinea, which, 
for the 100 fruits examined, had an average of 2.02 seeds to each fruit. 
The most productive in this group was Malus Malus flore pleno, which, 
for 100 fruits, had an average of 7.8 seeds to each fruit. The second 
in seed production was Malus microcarpa, which, for 100 fruits, had 
an average of 7.09 seeds to each fruit. 

Between the extremes in seed production given for the different 
classes of fruits the averages were various: no two were alike, but 
the majority tended towards approximation of the general average 
for the class. High seed production appeared to be characteristic of 
some orchard varieties, while certain others of these varieties were 
equally constant in low production. Some varieties tended to con- 
centrate within the normal of ten seeds, as was the case with Arkansas 
Black, Grimes, Fameuse, and Rome; others tended to scatter 
the production over a wide range, as 1 to 27 in Shockley, 3 to 21 in 
Rhenish May, and 3 to 19 in Winter Rambo. In the groups of apples 



ber of seeds per fruit 



14 15 | 16 | 17 | 18 | 19 | 20 | 21 22 23 | 24 



2 



3 2 

1 



1 
13 

205 



5 

198 



15 12 



6 1 

145 j 103 

17 16 



3 

29 



21 4 
5 7 



14 



















Table 1. — Seed Production in Orchard Varieties: 


Large Fruits 


































No. of 


Average 


AV (mmT' 


Distribution of 


A 7^f 


Distribution of fruits as to 


number of seeds per fruit 


\ anetv 


Long 


1 Trana- 




1 ve-ie 


I .-,'617 


1 8 




5 | 6 


'' 


8 | 9 | 10 


11 12 


isfa 


15 


16 


17 IS 


10 20 






25 21 


Ark:us;i.s Hl.ick 


200 
1393 
261 

200 

200 

200 
200 
374 
200 

200 
200 
863 
200 

2 398 

177 
328 
200 

166 
513 

1190 
550 

200 

200 


14-1 L'li 

1 75 20 
57.83 

115.66 

17S.r,9 

2011 11 

12lj)5 

120.76 
112.26 
141.18 
141.46 
151.95 

128.00 
154.93 
170.85 
105.17 
116.80 

107.10 

126.72 
2.1.1.70 
125.58 
121.16 

197.31 
132.10 

119.06 
106.09 
135.51 

207.94 

116216 


63.67 
58.84 
57.90 
41.72 

55.13 
68.22 
65.41 

67.01 
52.85 

50.32 
55.96 
60.39 
60.31 
57.88 

55.86 

57^29 

61.26 

50.80 
52.41 
68.64 
53.83 
59.04 

57^25 
54.10 

54^0 


74.16 
70.99 
74.00 
48.66 

66.33 
74.04 


199 

1392 

2 259 

11 189 

200 

4 96 


2 
80 

21 

117 

29 

110 


2 

3 
36 


9.23 
5.97 
4.09 
5.97 

9^8 

9.44 
7.10 
5.96 

7.97 
7.15 
5.90 
5.77 
5.18 

8.13 
7.00 
1 4.28 
9.33 
10.37 

11.65 
7.40 

8.'l4 

5.94 
8.30 

1 8.11 
8.60 

4 ' 9.98 

9.11 
9.74 


1 
4| 12 
3j 16 

2 




4 

38 
45 

1 

1 
32 


17 

26 
46 

5 
49 


14 
23 

38 
7 

11 

-6 
41 

106 
26 
29 
74 
35 

27 

71 

132 
43 

5 

56 
43 

28 

24 
46 
44 

12 


56 

11 
23 

13 

122 
41 
24 

50 

36 

18 

202 
45 

82 

38 

21 

112 

71 


41 

77 
5 
6 

13 

52 
49 

132 

18 

21 

11 
51 
32 

215 
24 

4 
66 
50 

10 
173 

676 

r,r, 

47 


20 
29 

7 
20 
52 

2 

100 
12 

29 

57 
40 

40 
39 

7 
108 
19 

525 
94 

38 


22J12 


sj 6 


2 


2 


















39 85 

is 11 


152 

42 




1 

2 
70 














2 

2 


8 










12 
25 

45 
4 
4 

2 


12 

22 
4 

1 
1 








2 1 






67.02 1 1 292 


s; is 














67.66 
64.59 

70231 
71.61 

69.25 
75.49 
73.31 
63.64 
67.54 

63.01 


649 

1 200 


. 18 ~ ~ 








2 9 




198 
12 

9 

7 








2 

2 
20 55 

1 
I 1 


11 
9 
4 

1 


17 29 

33 46 

2l 


28: 33 




















Mammoth Blark T« i u' , 
McClellan 


6 


199 

199 

837 
199 
198 

2 276 

1118 


43 
34 

2 

42 
17 

8 

5 

18 
13 
10 
5 


14 
26 
113 

8 

83 

24 

44 
17 

29 

23 
27 


1 

m 13 

301 205 
16 15 

3J 29 
6J 2 


: 


7 


' 






99 143 ' 145 


14 10 
27 16 

249 222 
4 2 
10 9 

13| 5 

2 3 

1 

43| 15 
66 46 

17 11 










Polische Jungfrau 


16 

1 1 

5 

1 2 

5 18 


2 

27 
9 

7 

■!, 
3 
7 


6 

115 

17 

14 


1 
103 
16 

7 


31 


12 
4 


4 


Smith Cider 

Tolman 

Twenty Ounce 


66.40 ! 
69.00 

78.90 


324 
165 




65.70 117 
61.42 ! 2 1 185 

68.72 1 391 






■ 




Winter Rambo 




Wythe 


51.19 67.81 ' l' 198 


i 






12012 




































as to number of seeds per fruit 


| 13' | 14 | 15 | 16 | 17 | 18 | 19 


| 20 


1 21 


22 


23 | 24 | 25 


26 | 27 


1 


3 

2 


1 


i 




















1 


1 


























1 


o 
























♦ 


5 


6 


3 1 


1 






















21 


15 


11 3 


3 


3 




















12 


10 


21 16 


16 


13 


11 


14 


9 


1 


2 








1 


2 




1 
























2 


1 
























12 


4 


4 1 


1 






















3 


3 


2 3 
























5 


5 


o 

























1917] Seed Production in Apples 189 

of large size, no fruits had less than four seeds in Garfield, Osceola, 
Polische Jungfrau, and Wythe ; none had less than three in Crawford, 
Rhenish May, Smith Cider, Willow, Winesap, and Winter Rambo. 

Seedless apples occurred in the large size-groups of McMahon and 
Twenty Ounce, in both size-groups of Ben Davis, Collins, Golden Ball, 
Minkler, and Wealthy, and in the small size-groups of Bailey Sweet, 
Indian, Jonathan, Isham, Osceola, Rhenish May, Shockley, Tolman, 
and Winesap ; they occurred rather more frequently among small 
apples than among large. Seedless apples will be referred to again in 
connection with detailed accounts of the several classes of fruits. 



ORCHARD VARIETIES 

Records of numbers of carpels and distribution of seeds for the 
two size-groups of orchard varieties are brought together in tabular 
form in Tables 1 and 2. Records of ovule production of the orchard 
varieties are presented in Table 7. 

Distribution of seed production in its relation to the full normal 
content of ten seeds is of interest as showing the extent of departures 
from the normal in both directions. Considering the apples according 
to the classes into which they have been divided, the apples of large 
size as produced by orchard varieties may come first. 

Seed Distribution of Apples of Large Size 

The apples of large size included thirty-two varietal groups, aggre- 
gating 12,912 apples ; they produced 106,845 seeds, an average of 8.27 
seeds to each fruit. The number of apples producing the normal of 
ten seeds was 1,610, or 12.5 percent of the whole number. These 
apples bore 16,100 seeds, or approximately 15 percent of the number 
of seeds produced by all fruits of the group. The number of apples 
falling below normal in seed production was 8,913, or 69 percent of 
the total ; these apples bore 58,412 seeds, or 54.67 percent of the total 
produced by fruits of this class. With seed production above normal 
there remained 2,389 apples, or 18.5 percent of the total ; these bore 
32,333 seeds, or 30.26 percent of the total seeds. 

Seed Distribution of Apples of Small Size 

The groups of small apples represented thirty varieties, and to- 
gether contained 8,500 apples which produced 61,325 seeds, an average 
of 7.21 to each fruit. The number of apples producing the normal of 
ten seeds was 1,020, or 12 percent of the total; these produced 10,200 
seeds, or 16.63 percent of the total. The number of apples producing 
less than ten seeds was 6,786, or 79.84 percent of the total; these 
produced 42,178 seeds, or 68.78 percent of the seeds produced by the 



190 Bulletin No. 203 [August, 

group. The number of apples with seeds ranging above ten was 694, 
or 8.16 percent: these produced 8,947 seeds, or 14.59 percent of the 
seed total. 

Comparison of Seed Distribution of the Two Size-groups 

Comparing the size-groups, it is seen that the percentages of fruits 
having the normal number of ten seeds were nearly the same, 12.5 
percent for the large and 12 percent for the small. In numbers of 
fruits having seeds in excess of ten the large fruits lead by a consider- 
able margin ; the percentages were 18.5 for large and 8.16 for small. 
Of fruits with less than the normal number of seeds, small fruits had 
the greatest numbers, nearly 80 percent as compared with 69 percent 
for large fruits. Seedless fruits numbered 37 among large apples and 
64 among small apples. Apples having one seed each numbered 93 
for the groups of large apples and 121 for the groups of small apples. 
With two seeds each there were 231 large apples and 277 small apples ; 
from this there was a gradual increase in number of apples with 
each addition to the seeds to each fruit, until the maximum of 1,843 
apples of large size and 1,257 apples of small size was reached 
with nine seeds to each fruit. Above this the decline in numbers 
was rapid for both classes, but there were still a considerable number 
of apples having large excess in numbers of seeds. Thus, 95 large 
apples had eighteen seeds each, 48 had nineteen each, and 36 had 
twenty or above. Among small apples, 16 had eighteen seeds each, 
11 had nineteen each, and 27 had twenty or above. 

Number and Distribution of Carpels 

The number of carpels in a normal apple is five, but just as there 
are more or less frequent abnormalities in number of floral parts, 
sepals, petals, and stamens, so there are departures from the normal 
in number of cells in the compound ovary. Among fruits of orchard 
varieties examined there were found 789 apples, or 3.68 percent of the 
total number, that departed from the normal in number of cells. In- 
crease in number was much more frequent than diminution ; 129 fruits 
had less than five cells and 660 had more than five. 

Distribution of the abnormalities among varieties was not at all 
uniform. Winter Eambo had more than any other variety, 243 out 
of 1,050 apples, or 23.14 percent: 1 fruit had four cells, 186 had six 
cells, 50 had seven cells, and 6 had eight cells, while 807 were normal 
with five cells each. Rhenish May had the next largest number of 
fruits showing departures from normal, 219, but because of the larger 
number of apples examined the percentage was only 6.42, much lower 
than for Winter Rambo. In this variety .there were 8 fruits with 
three cells each, 50 with four cells, 160 with six cells, and 1 with seven 



1917] Seed Production in Apples 191 

cells. Huntsman had the third largest number of abnormalities, with 
130 six-celled fruits and 2 having seven cells each. This variety was 
represented by 1,261 apples, and the percentage of departures from 
normal was 10.46. Numbers of fruits with other than normal cells 
were very much smaller for the remaining twenty-five varieties among 
which they were distributed. Five of these varieties, Bailey Sweet, 
Grimes, Osceola, Twenty Ounce, and Wolf River, with an aggregate of 
1.911 apples, had each one six-celled fruit, all others being five-celled. 
Four varieties, Indian, Isham, Jonathan, and Shockley, with a total 
of 1,606 apples, had only five-celled fruits. 

As between the two size-groups, large and small, there was very 
little difference in the frequency with which abnormalities in cells 
appeared. In the group of large apples there were 474 fruits having 
cells above or below the. normal number; in the group of small apples 
the number was 315, but large apples were more numerous than small 
and the ratio of abnormalities was practically equal for the two groups. 

Varieties High in Seed Production 

Certain of our varieties exhibited an exceptionally strong tendency 
to multiplication of seeds; at least three of these, Winter Rambo, 
Rhenish May, and Shockley, are perhaps worthy of individual 
consideration. 

winter rambo 

In the large size-group of Winter Rambo were four apples, each 
with eight cells containing plump and abortive seeds, as follows : 10-6, 
16-3, 11-5, and 12-4. In the second of these fruits there was an 
addition of three to the expected number of ovules. Irregularity in 
number of ovules appeared to be characteristic of this variety; the 
range was from the normal of 10 for a five-celled fruit to 24 for a 
six-celled fruit. One of the fruits examined had six cells with 4 ovules 
in each cell, 19 of which developed into seeds. Of 550 Winter Rambo 
apples of large size, 35, or more than 6 percent, had each seven cells. 
These apples contained 565 ovules, an average of 16.14. The expected 
total of ovules in 35 seven-celled apples is 490 ; hence there was here 
an excess of over 15 percent. The seeds that developed numbered 
411 ; this represents 72.75 percent of the ovules present, but falls a 
little more than 16 percent below the full complement for 35 seven- 
celled fruits. The lowest seed production in these fruits was six in 
one fruit having 14 ovules; the maximum production was seventeen 
seeds in a fruit having 17 ovules. The maximum seed production in 
this variety falls to two six-celled apples, one of which had 19 ovules, 
all of which formed good, plump seeds ; the other had 24 ovules, 19 of 
which became fully developed seeds. At the other extreme were two 



192 Bulletin No. 203 [August, 

fruits with three seeds each, both having the expected number of 
ovules, one fruit five-celled, the other six-celled. 

In this variety there were considerable differences between large 
fruits and small fruits in number and distribution of seeds. These 
differences are best shown by a direct comparison of the distribution 
percentages presented in Table 3. 

Table 3. — Distribution of Seeds in Large and Small Winter Eambo Apples 





Number 

of 

apples 


Distribution of se 


3ds 

Percentage 
above normal 


Average 


Size-group 


Percentage Percentage 
normal ( below normal 


seed 
content 


Large 

Small 


550 
500 


17.09 
13.80 


45.64 
72.00 


37.27 
14.20 


9.98 
8.30 



Note. — Normal is here taken to be ten seeds to each five-celled fruit. 

The large fruits exceeded the small fruits by more than 20 percent 
in average of seeds to each fruit and by more than 32 percent in 
number of seeds produced. The fruits having seeds in excess of the 
normal were nearly three times as numerous in the group of large 
apples as in the group of small apples, while of the apples below 
normal in seed production the small apples exceeded the large by about 
35 percent. In this variety, then, it is evident that the large fruits 
were greater seed producers than were the small fruits. 

RHENISH MAY 

The second of the three varieties showing greatest tendency to multi- 
plication of seeds was Rhenish May, in which the large size-group was 
represented by 2,398 apples and the small size-group by 1,009 apples. 
For the large apples the average seed production was 11.65 and for 
the small apples 7.55. Ten percent of the large apples contained 
ten seeds each and produced 9 percent of the seed total for large 
apples; 30 percent had numbers of seeds below ten and carried 19 
percent of the total number of seeds, while 60 percent of the fruits 
had seeds in excess of ten and carried 72 percent of the seeds. In the 
group of small apples the percentage of fruits having the normal of 
ten seeds each was 10, the same as for the large apples, and they had 
13.3 percent of the seeds borne by the group. The percentage of fruits 
with less than ten seeds was very much greater than for the large 
fruits, 72.4 percent as against 30 percent for the large fruits, and 
these carried 58.1 percent of all the seeds. Only 17.6 percent of this 
group had above ten seeds each, but they produced 28.6 percent of the 
total number of seeds. The superiority of large apples as compared 
with small apples in seed production was as well defined in Rhenish 
May as in Winter Rambo. In Table 4 arc presented the figures for seed 
distribution in Rhenish May. 



1917] 



Seed Production in Apples 



193 



Table 4. — Distribution of Seeds in Large and Small Ehenish May Apples 





Number 

of 
apples 




Distribution of seeds 






Size- 


Normal 


Below normal Above normal 


Average 

seed 
content 


groups 


j Per- 
Percent centage 
of total 


Percent 


Per- | 
centage Percent 
of total 


Per- 
centage 
of total 


Large. . . 
Small.... 


2398 
1009 


10 
10 


9.0 
13.3 


30.0 19.0 i 60.0 
72.4 | 58.1 | 17.6 


72.0 
28.6 


11.65 

7.55 



SHOCKLEY 

The third of the three varieties standing highest in seed production 
was Shockley. The multiplication of seeds in this variety was so 
pronounced that it was really in a class by itself. As with other varie- 
ties, the fruits were divided into two size-groups ; each group contained 
177 apples. There were no departures from normal in number of 
cells; each fruit had five. Unlike the other varieties there was, in 
Shockley, but very little difference in seed distribution between large 
apples and small apples. The tendency to multiplication was about 
the same in all fruits, and appeared as a well-established varietal 
characteristic. Averages of seeds to each fruit and seed distribution 
are shown in Table 5. 



Table 5. — Distribution of Seeds in Large and Small Shockley Apples 



Size- 


Number 

of 
apples 


Distribution of seeds 


Average 


groups 


Normal | Below normal | Above ] 


lormal 
Percent 


seed 
content 




Number Percent | Number | Percent Number 


Large. . . 
Small.... 


177 
177 


4 

7 


2.26 
3.96 


21 
19 


11.86 
10.73 


152 
151 


85.88 15.04 
85.31 | 14.59 



The total number of ovules in all fruits was 6,536, an average of 
18.5 for each fruit. As between the two size-groups, the large apples 
had 3,298, or 50.5 percent, and the small apples 3,238, or 49.5 percent, 
a nearly equal distribution. Of the total ovules 80.3 percent developed 
into seeds ; and here, also, the division between large and small fruits 
approximated equality. The lowest number of ovules in any fruit 
was 10 in one small fruit. Three large fruits and one small fruit 
had each 11 ovules, and two large and five small had each 12. At 
the other extreme, one large fruit had 27 ovules, 21 of which developed 
into seeds, and one small fruit had 27 ovules, all of which became 
seeds. Two large fruits had each 26 ovules : one of these developed 
24 seeds, the other 22. Four fruits had 25 ovules each with an average 
of 21 seeds. The maximum frequency of ovules falls on 20, there 
being thirty-one large apples and thirty-six small apples having each 



194 Bulletin No. 203 [August, 

this number. These apples having 20 ovules each showed wide range 
in seed development. Of the large fruits, one had 1 seed, one had 2, 
and one had 5 ; and at the other extreme, three developed the total of 
20 each, two had 19 each, and five had 18 each. Among the small 
apples having 20 ovules, four had no seeds; one had 11 seeds, two had 
13 each, and nine had the full complement of 20 each. Aside from 
the four apples just referred to as having 20 ovules each and no 
developed seeds, were two others in the same group that were seedless ; 
one of these had 17 ovules, the other 15. Some of the ovules in these 
six seedless fruits had enlarged the integuments somewhat, but none 
approached the size of mature seeds and all were perfectly flat, with 
nothing to indicate any activity in the direction of embryo develop- 
ment. 

In order to indicate the position with regard to* the size and weight 
of these parthenocarpic fruits as compared with other apples of the 
same group that stand high in seed production, six apples, each having 
twenty ovules, all represented by apparently perfect seeds, were taken 
at random and are shown in comparison with six seedless fruits in 
Table 6. 

Table 6. — Comparison of Seedless Fruits with Fruits of High Seed 
Production as to Size and Weight: Shockley 





Aver, weight 
in grams 


Aver, diameter (mm.) 




Long 


Transverse 


Six seedless fruits 


102.75 
94.49 


49 
51 


64 


Six fruits with 20 seeds each 


58 







It here appears that the parthenocarpic fruits were not the smallest 
in the group, as they exceeded an equal number of fruits that were 
highly productive of seeds, both in weight and in transverse diameter. 
The stimulus of the assumed pollination developed fruits of good 
size in the absence of fertilization. Fig. 1 shows abnormal seed pro- 
duction in Shockley. 

HUNTSMAN 

One other variety may be referred to here, the Huntsman, not so 
much because of its high seed content, altho one fruit reached a 
maximum of 18 seeds, but because of the symmetry of parts, the very 
open character of the core, the size and uniformity of cells, and the 
breadth of carpels. The variety was represented by 731 large fruits and 
530 small. The average seed content of the large apples was 7.97; 
of the small apples, 6.66. Over 11 percent of the fruits had 11 or 
more seeds each, bringing the variety to fourth place on the list in 
this particular. It was exceeded by Shockley, Rhenish May, and 



1917] 



Seed Production in Apples 



195 




Fig. 1. 



-Seed Production in Shockley. Portions of Fruits Showing Number 
and Arrangement of Seeds in Various Carpels 



"Winter Rambo, percentages for which have been given. The one 
fruit that had 18 seeds was photographed in section to show regularity 
of cells and high seed content ; there were six cells, each with 3 plump 
seeds. This apple weighed 156 grams, and measured 54 mm. in 
longitudinal diameter and 72 mm. in transverse diameter. A section 
of the fruit appears in the front cover illustration. 



Varieties Low in Seed Production 

Of the least productive varieties, Collins had the lowest seed content 
of any of the varieties examined. The 261 large apples had an 



196 Bulletin No. 203 [August, 

average of 4.09 seeds ; the maximum of nine was reached by 5 fruits, 
16 fruits had only one seed each, and 48 had two each; three were 
seedless. The 150 small apples averaged 2.8 seeds; this was the lowest 
average found for any group. Four fruits had seven seeds each ; this 
was the maximum for the group. Twenty- two had one seed each ; 40 
had two each, and 12 fruits were seedless. The apples of this small 
size-group were well above the size limit for No. 1 apples, as is shown 
by the average transverse diameter of 68 mm. and by the average 
weight, 134 grams. 

Next above Collins in seed production was Minkler. In the large 
size-group of this variety there were 863 apples, which produced 3,694 
seeds, an average of 4.28 to each fruit : 4 fruits had each the maximum 
of ten seeds, 55 had one seed each, 99 had two seeds each, and 20 
were without seeds. The apples of this group had an average trans- 
verse diameter of 73.31 mm., and the average weight was 170.85 grams. 

The small size-group numbered only 54 apples with an average 
of 3.65 seeds to each apple : two fruits had eight seeds each, the max- 
imum for the group, and three fruits were seedless. 

Seed Production in the Remaining Varieties 

The twenty-six varieties that have not been specifically mentioned 
had various seed averages. In fourteen of them the range of averages 
was between 5 and 8 seeds to each fruit and in twelve it was between 
8 and 11. With two exceptions the groups of large apples had dis- 
tinctively greater seed averages than the groups of small apples. The 
two exceptions were Shockley, already mentioned in detail, in whicli 
the difference in size-groups was very slight, and McMahon. In this 
latter variety the number of apples was 200 for each group. The 
group of large apples had an average of 7 seeds to each fruit and 
the group of small apples an average of 7.75 seeds. The small apples 
also reached a higher maximum: two fruits had 14 seeds each, while 
only one fruit, in the group of large apples, reached a maximum of 13. 

Size of Fruit in Relation to the Percentage of Ovules 
Developed as Seeds 

Another method of determining the relative seed production of 
large apples and small apples is by comparing the number of developed 
seeds in each of the two groups for each variety. Records obtained 
from twenty-one varieties are presented in Table 7, showing for each 
size-group the number of apples, the number of cells, the normal 
ovule content, allowing two to each cell, the number of ovules actually 
present, the excess above normal, the number of good seeds, the aborted 
seeds, and the percentage of ovules actually present that developed 
as seeds. 



1917] 



Seed Production in Apples 



197 



Table 7. — Ovule Production in Orchard Varieties 



Variola 



Num 

ber 

of 
apples! ~~ els 



Num- 
ber 
of 



Ovules 



car- 



Nor- 
mal 
num- 
ber 



Num- 
ber 
found 



Excess 



Num- 
ber 
devel- 
oped 



Num- 
ber 
un- 
devel- 
oped 



Large Apples 



Bailey Sweet 

Collins 

Crawford 

Fameuse 

Golden Ball 

Hibernal 

Indian 

Isham 

Mammoth Black Twig. 

McClellan 

McMahon 

Osceola 

Polische Jungf rau .... 

Eome 

Shockley 

Tolman 

Wealthy 

Willow 

Winter Rambo 

Wolf River 

Wythe 



200 


1001 


2002 


261 


1303 


2606 


200 


989 


1978 


200 


1000 


2000 


200 


1002 


2004 


200 


1000 


2000 


200 


1000 


2000 


200 


1000 


2000 


200 


1001 


2002 


200 


999 


1998 


200 


998 


1996 


200 


1001 


2002 


200 


1002 


2004 


200 


1002 


2004 


177 


885 


1770 


200 


1004 


2008! 


513 


2566 


5132 


150 


788 


1576 


550 


2950 


5900 


200 


1001 


2002 


200 


1000 


2000 



2288 
2606 
2019 
2003 
2114 
2008 
2156 
2052 
2002 
2010 
2208 
2157 
2339 
2029! 
3298 
2034| 
5135, 
1595] 
6778 
2167 
2321 



Total j 4851 1 24492 : 48984| 53319 



286 


1846 


441 




1067 


1539 


41 


1294 


72t 


3 


1303 


70C 


110 


1888 


226 


8 


1192 


816 


156 


1430 


726 


52 


1180 


872 


. , . 


1036 


966 


12 


1627 


383 


212 


1400 


808 


155 


1862 


295 


335 


2073 


266 


25 


1479 


550 


1528 


2665 


633 


26 


1628 


406 


3 


4260 


875 


19 


1235 


360 


878 


5488 


1290 


165 


1823 


344 


321 


1948 


373 


4335 


39724 


13595 



Small Apples 



Bailey Sweet 

Collins 

Crawford 

Fameuse 

Golden Ball , 

Hibernal 

Indian 

Isham 

Mammoth Black Twig, 

McClellan 

McMahon 

Osceola 

Polische Jungf rau 

Rome , 

Shockley 

Tolman 

Wealthy 

Willow 

Winter Rambo , 

Wolf River ; 

Wythe 



199 


995 


1990 


150 


742 


1484 


200 


979 


1958 


200 


1000 


2000 


200 


1001 


2002 


200 


998 


1996 


200 


1000 


2000 


200 


1000 


2000 


200 


997 


1994 


• 200 


999 


1998 


200 


998 


1996 


200 


1000 


2000 


200 


1001 


2002 


200 


1000 


2000 


177 


885 


1770 


200 


1003 


2006 


500 


2498 


4996; 


200 


1026 


2052 


500 


2603 


5206 


200 


1000 


2000 


200 


999 


1998 



2117 
1484 
1979 
2002 
2066 
2011 
2020 
2026 
1994 
2004 
2295 
2014 
2149 

2009; 

3238! 
2006 
5002 
2113! 
5540| 
2150 
2166J 



Total 1 4726 | 23724J 47448| 50385[ 

Average. 



127 


1645 


472 




420 


1064 


21 


1051 


928 


2 


1036 


966 


64 


1794 


272 


15 


1148 


863 


20 


809 


1211 


26 


1066 


960 




724 


1270 


6 


1498 


506 


299 


1551 


744 


14 


1341 


673 


147 


1729 


420 


9 


1196 


813 


1468 


2584 


654 




1362 


644 


6 


3978 


1024 


61 


1558 


555 


334 


4148 


1392 


150 


1629 


521 


168 


1673 


493 


2937 


33940 


16445 



67.36 J 



198 Bulletin No. 203 [August, 

The number of large apples was 4,851 ; of small apples, 4,726. 
In all but three of the varieties the numbers of ovules present in the 
groups of large fruits were higher than in the groups of small fruits. 
The exceptions to the rule were: Hibernal, in which variety the 200 
fruits in the small size-group had three more ovules than had the 
200 apples in the large size-group, a difference so small as to bring 
the groups practically to equality ; MacMahon, in which the group of 
small apples exceeded the large in total number of ovules by eighty- 
seven ; and Willow, in which, taking into consideration the fact that 
the group of small apples exceeded the large by fifty in number of 
fruits, there was an excess of thirteen ovules for the small group. Of 
those varieties in which large apples exceeded small apples in numbers 
of ovules, Fameuse had the least difference and Winter Rambo the 
greatest. The average difference for all varieties approximated one 
hundred. 

Some varieties exhibited little tendency to increase in number of 
ovules above the normal ; others had the tendency strongly marked. 
In Collins and Mammoth Black Twig there was no excess in either 
size-group ; in Tolman there was no excess in the small size-group, 
but an excess of twenty-six in the large size-group. All others had some 
excess in both groups, ranging, in the groups of large apples, from 
three for Fameuse and Wealthy to 1,528 for Shockley, and in the 
groups of small apples, from two for Fameuse to 1,468 for Shockley. 

The percentages of ovules found present that were followed by 
plump and apparently viable seeds are, perhaps, the best gage of 
the relative seed-producing capabilities of the large and the small 
apples. Of the twenty-one varieties under consideration, all but one 
had the higher percentages of seeds developed in the groups of large 
apples. The one exception was McMahon, which had 63 percent of 
the ovules developed into good seeds in the group of large apples, and 
68 percent thus developed in the group of small fruits. Percentages 
for the list of varieties other than McMahon ranged, for the groups 
of large apples, from 41 percent for Collins to 89 percent for Golden 
Ball. Half the varieties had percentages of 80 or above ; others were 
somewhat less, but the average for the twenty varieties was 75 percent. 
On the other hand, the range of percentages of plump seeds for the 
groups of small apples was between 28 for Collins and 87 for 
Golden Ball, with an average for the twenty varieties of 67. In some 
varieties the differences between groups were small, as for example, 
Hibernal with a percentage of 59 for large apples and 57 for small, or 
Shockley with 81 percent for large and 80 percent for small. In others 
the differences were considerable, as in Mammoth Black Twig with 52 
percent for large and 36 percent for small, or Indian with 66 percent 
for large and 40 percent for small. For the small apples of the twenty 
varieties taken together, the average of seeds developed was 67 percent 
of the possible as against 75 percent for the large apples. 



1917] 



Seed Production in Apples 



199 



In separating large apples from small apples for the groups con- 
sidered above, a gap of 5 mm. was left between, that is to say, the 
minimum transverse diameter admitted to the group of large apples 
was 5 mm. more than the maximum transverse diameter included in 
the group of small apples. To test the effect of greater size difference 
between groups, the 100 largest Winter Rambo apples were selected 
for comparison with the 100 smallest of the same variety. The original 
groups of Winter Rambo numbered 550 large and 500 small, a suf- 
ficient number for a fair test of extremes. 

These selected centenary groups ranged in transverse diameters 
as follows : the large apples from a minimum of 72 mm. to a maximum 
of 87 mm., with an average of 75 mm. ; the small apples from a min- 
imum of 40 mm. to a maximum of 52 mm., with an average of 48 mm. ; 
the gap between groups was 20 mm., and the averages differed by 
27 mm. The averages for the groups are tabulated below : 



Table 8. — Comparison of Centenary Groups of Large and Small 
Winter Rambo Apples 



Size-group 


Aver. 

weight 

in grams 


Average diameter 
in mm. 


Aver. No. 
good seeds 


Aver. No*, 
undevel- 
oped ovules 


Percentage 
of ovules 


Long 


Transverse 


forming 
seeds 


Large 

Small 


167 59 
57 39 


75 

48 


10.64 
6.49 


2.53 
3.24 


81 
67 



In the original group of 550 large apples the average seed content 
was 9.98 ; in this group restricted to the 100 largest it was 10.64, an 
increase of nearly 7 percent, and there was a corresponding increase 
in the number of ovules that did not develop. The percentage of 
ovules forming seeds was the same in both groups. 

In the group of 500 small apples the average seed content was 8.3. 
The 100 smallest apples of this group had a seed average of 6.49, 
nearly 22 percent less than that of the full group. The increase in 
undeveloped ovules was over 14 percent and the decrease in per- 
centage of seeds formed was about 8 percent. As between the centenary 
groups, the percentages of ovules developing into good seeds were 
81 for the large apples and 67 for the small apples. 

This comparison between the extremes in size found in apples of 
one variety confirms the results obtained in the analysis of seed pro- 
duction for all the varieties and strengthens the evidence which, taken 
together, appears to establish the fact that large apples develop a 
considerably larger proportion of the ovules they contain than do 
small apples. 

In Table 7 is reported the ovule production of twenty-one varieties 
represented by 9,577 apples nearly equally divided into two groups 



200 Bulletin No. 203 [August, 

on the basis of size. Examination in detail of the ovule and seed 
content of these apples indicates in a positive way that large apples 
are superior to small apples in seed production. The large apples 
contained nearly 6 percent more ovules than did the small apples, 
the total of seeds produced was 17 percent greater, and the percentages 
of ovules developed into seeds were, with the one exception cited, 
higher for the groups of large apples than for those of small apples. 

SPECIES OF MALUS 

The fruiting forms of the genus Mains included in the record of 
seed production number twenty-five. They represent seventeen named 
species and six classed as varieties, besides two, the Hyslop and Yellow 
Siberian Crabs, carried under their common names. There is much 
confusion in the nomenclature of the species of the genus and the 
taxonomic rank of some of our forms is uncertain, and cannot be 
definitely determined until a complete monograph of the genus is 
available. Three of the forms, namely, Mains Ioensis, the wild crab 
of the middle west, Malus Soulardi, the Soulard Crab, and Mains 
fusca, the Oregon Crab, are native. Malus Arnoldiana is a seedling 
of Malus floribunda originated at the Arnold Arboretum several years 
ago. Malus prunifolia var. (856) also originated at the Arnold 
Arboretum from seed collected in Japan in 1892 by Dr. C. S. Sargent. 
The names with descriptions of these two have not yet been published, 
but doubtless will be in the near future. It is probable that one or 
two of the other forms are seedlings having origin in this country, 
but with these definite and possible exceptions the forms in the list 
are of European or Asiatic origin. 

The fruits of each species or variety were weighed and the average 
weight was recorded. Each individual was measured with calipers 
for longitudinal and transverse diameters. It was then cut trans- 
versely and record made of the number of carpels and the number 
and distribution of developed seeds and undeveloped ovules. The 
aggregate of fruits examined was 6,642, varying for the different 
lots from 22 for M. fusca to 1,200 for M. Ringo sublobata. M. fusca 
had small representation because but few fruits were available; all 
others had 100 or more fruits. The average weight for all fruits was 
9.96 grams ; if the two large crabs, Hyslop and Soulard, are eliminated, 
this average drops to 7.46 grams. Five of the forms had fruits which 
averaged less than one gram in weight, and four, besides the two 
crabs just mentioned, had fruits that averaged above 10 grams. *As 
a means of giving a right impression of the range in size and form 
and the relative sizes of the different crabs, a single fruit of each of 
the twenty-five forms is shown, natural size, in Figs. 2 to 7, inclusive. 

Table 9 gives the distribution of carpels, the seed distribution, and 
the percentage of ovules forming good seeds for each of the twenty- 
five crab-like forms. 



1917] 



Seed Production in Apples 



201 




202 



Bulletin No. 203 



[August, 




co 



EH . 

B 5 






^ g 
•♦ 'a 

W g 
o • 

O W 

<*§ 

nil 

W 

£'& 

Eh 
J < 
<1 ^ 

is 



1917] 



Seed Production in Apples 



203 




204 



Bulletin No. 203 



[August, 




1917] 



Seed Production in Apples 



205 




Fig. 6. — Crabs, Natural Size. Left to Eight: Yellow Siberian Crab (857), 
Malus fastigiata bifera, Mains Ioensis 




Fig. 7. — Crabs, Natural Size. Left to Eight: Malus Arnoldiana, Malus fusca, 
Malus floribunda, Malus Sargenti, Malus atrosanguinea, Malus Toringo (19664) 



Number and Distribution of Carpels 

There were wide differences among species in number and distribu- 
tion of carpels ; the range in numbers was from 2 to 12. The minimum 
of two carpels was found in two species, M. Arnoldiana and M. Sar- 
genti. M. Arnoldiana, represented by 100 fruits, had two fruits each 
with two carpels; in both, the ovules were as expected, two in each 
cell ; one developed three plump seeds, the other only one. M. Sargenti, 
represented by 223 fruits, had one fruit with only two carpels, con- 
taining four ovules ; one good seed developed in each carpel. At the 



206 Bulletin No. 203 [August, 

other extreme M. spectabilis (No. 615) had one fruit with twelve 
carpels and another with eleven. In these two cases the large number 
of carpels was due to the appearance of a second whorl of carpels 
superposed upon the normal whorl. The fruit having twelve carpels 
had seven in the basal whorl and five in the upper whorl : these twelve 
carpels contained thirty-one ovules, ten of which developed into plump 
seeds, and of this ten, three were in the carpels of the superposed 
whorl. Nine other fruits had the additional whorl represented by 
one or two carpels and these carpels all contained developed seeds. 
The remaining 89 fruits of this species had carpels distributed as 
follows : 13 with the normal of five, 49 with six carpels each, 22 with 
seven, and 5 with eight each; but in all these fruits the additional 
carpels were crowded into the one whorl. 

Those fruits possessing the secondary whorl of carpels gave external 
evidence of its presence in enlargements which appeared as protuber- 
ances projected vertically about the basin. These protuberances coin- 
cided with those carpels in which seeds were developed, and for those 
cases in which the seed development was distributed around the whorl, 
the calyx appeared as the bottom of a deep, irregular basin, while 
for those in which only one or two seeds, in close proximity, on one 
side, were developed, the resulting protuberance gave a one-sided fruit 
with the calyx appearing as if on the side of the apple. See Central 
fruit in Fig. 5. 

Two other species showed a strongly developed tendency to multi- 
plication of carpels; these were M. Mains flore pleno and M. Scliei- 
deckeri. The first had 3 fruits with a maximum of nine carpels, 8 
fruits with eight carpels each, 21 with seven each, 49 with six each, 
and only 19 with the normal five carpels. The second had a maximum 
of eight carpels, represented by one fruit; 82 fruits had each seven 
carpels, and 309, or 51.5 percent of the total of 600, had each six 
carpels. Two hundred and six fruits had each the normal of five 
carpels, and two fruits had only four carpels each. The range for the 
first species was 5 to 9, for the second, 4 to 8. 

Considering the aggregate of 6,642 fruits representing the twenty- 
five crab forms, it appears that 4,565 fruits, or 68.73 percent, had each 
the normal five carpels. With numbers of carpels less than five there 
were 1,483 fruits, or 22.33 percent; and the aggregate of fruits with 
numbers of carpels above normal was 594, or 8.94 percent. 

The two crabs with fruits of large size, Hyslop and Soulard, 
exhibited no departures from the normal of five carpels. All other 
crabs showed variation in numbers of carpels: twelve varied only in 
the direction of diminished numbers, four only in the direction of 
increased numbers, and seven showed variations in both directions. 

The species bearing very small fruits tended more strongly to 
reduction in numbers of carpels than did the species having larger 



Four 


Five 


271 

7 


68 
391 



1917] Seed Production in Apples 207 

fruits; for example, compare 100 fruits each of the four species 
M. Toringo, M. Sargenti, M. floribunda, and M. atrosanguinea, whose 
fruits averaged less than one gram in weight, with equal numbers of 
the four forms M. baccata (red fruit), M. baccata (red fruit, late), 
M. baccata maxima, and M. prunifolia var. (838), whose fruits ranged 
in average weight from 6.62 grams to 9.63 grams. The distribution of 
carpels in these forms of Malus was as follows : 

Number of Carpels 

Three Four Five Six 

Small-fruited species 61 

Larger-fruited species 1 

For the small-fruited species 83 percent of the fruits had numbers 
of carpels less than five, while only 17 percent had the normal num- 
ber. For the larger-fruited species only 2 percent of the fruits had 
less than five, 97.75 percent were normal, and one fruit, or % °f 1 
percent, had one more than the normal of five. 

While it was generally the case in this crab group that the very 
small fruits showed the greatest tendency to reduction in numbers 
of carpels, there were exceptions, as in the case of one variety of 
M. prunifolia, the 600 fruits of which had an average weight of 10.64 
grams and in which 506 fruits, or 84.33 percent, had numbers of car- 
pels less than five. 

Seed Production 

The averages of seeds contained in fruits of the twenty-five spe- 
cies and varieties of Malus included in the list ranged from 1.32 for 
M. fusca, which was represented by only 22 fruits, and 2.02 for 
M. atrosanguinea, represented by 100 fruits, to 7.8 for M. Malus flore 
pleno. For all forms considered together the aggregate of seeds pro- 
duced was 28,050, which gives an average of 4.22 seeds to each fruit. 
The range shown was rather wide, and the general average decidedly 
lower than for the small fruits of orchard varieties. In distribution 
the range was from to 14. There were 94 parthenocarpic fruits, 
representing nine of the species. Seventy-eight, or nearly 83 per- 
cent of these, occurred in the variety sublobata of the species Bingo 
(19689) ; the remaining 16 were found in numbers from 1 to 4 in 
eight other species. Fruits with one seed each numbered 574 ; these 
were distributed among nineteen of the species in numbers from 1 
for M. Ringo and M. Sib erica frutico coccinea to 312 for the variety 
of M. Ringo, which is so productive of parthenocarpic fruits. With 
two seeds each there were 1,037 fruits, with three seeds each, 1,130 
fruits: this was the maximum frequency. Numbers for higher seed 
content decreased moderately at first and then more rapidly until the 
maximum of fourteen was reached by one fruit of M. Malus flore pleno. 



208 Bulletin No. 203 [August, 

This species had 2 fruits with thirteen seeds each, 6 with twelve seeds 
each, and 4 with eleven each. Four other species had one fruit each 
reaching a maximum content of eleven seeds. With ten seeds each, 
there were 65 apples, less than 1 percent of the total number of fruits 
examined. Eight species reached their maxima at ten seeds, and only 
five species had more than this number. 

In 31. fusca the highest number of seeds was three in each of two 
fruits, but the number of fruits of this species was too small to 
warrant the assumption that this maximum is normal. Next above 
31. fusca two species, M. atrosanguinea and 31. floribunda, had the 
number five as the maximum of seeds produced ; each was represented 
by 100 fruits ; the former had one fruit, the latter three fruits, each 
of which had five seeds. 

As with seed production in the orchard varieties, some of these crab 
forms tended to concentrate within a small range, as between 1 and 5 
for 31. atrosanguinea and 31. floribunda, two closely related species; 
some tended to wider range, as 2 to 14 for 31. Malus flore pleno, or 
to 11 for M. baccata (red fruit) and 31. Bingo. Some of the species 
had very small seeds, and in some the seeds were nearly as large as 
the average in orchard varieties. The size and shape of the seeds of 
the twenty-five crab-like forms are shown in Fig. 8 (natural size). 

Numbers of Ovules 

It developed in examining the apples here considered that for most 
species the normal complement of two ovules to the carpel, or ten for 
an apple with five carpels, held with great regularity. In twelve of 
the species not a single departure in either direction from the expected 
normal was found. This group of twelve species contained 2,947 
fruits which had an aggregate of 13,557 carpels and exactly double 
this number of ovules; each carpel had its full complement of two, 
no more and no less. Approximately one-half the ovules developed 
into seeds that appeared normal and viable; the seeds numbered 
13,622, representing 50.24 percent of the contained ovules. The un- 
developed ovules numbered 13,492, representing 49.76 percent of the 
total number; these were of all sizes, some so small as to require a 
hand lens for clear determination, others with integuments developed 
to nearly full size, but perfectly flat and containing no embryos. Nine 
other species had ovules in excess of the normal in numbers ranging 
from 1 to 300. The total of ovules above normal was 421 distributed 
in 158 fruits. Of this number 300 were found in fruits of 31. specta- 
bilis and 81 in fruits of 31. Malus flore pleno, two species that are 
abnormal in most flower and fruit characters. Excluding these two 
species, the other seven species of this group had an excess above 
normal of 40 ovules distributed in 35 fruits. 

31. spectabilis far exceeded all others in number of surplus ovules. 
This species had 300, or 71.25 percent, of the total surplus, and these 



1917] 



Seed Production in Apples 



209 








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210 Bulletin No. 203 [August, 

were distributed in 91 of the 100 fruits examined in numbers vary- 
ing from one to eleven. 

The 81 surplus ovules in M. Malus flore pleno were distributed in 
32 fruits in numbers ranging from one to six. 

The maximum number of ovules was 25 in a fruit of M. spectabilis 
having seven carpels : four of the carpels contained 4 ovules each and 
three carpels had 3 each. The maximum for individual carpels 
was 5 ovules; this number was found in several cases in this same 
species. Where 4 or 5 ovules are present, they are arranged in two 
ranks along the placenta at the inner margin of the carpel. 

In the four remaining species departures .from the normal in the 
direction of decrease in numbers were recorded. These shortages were 
small ; 16 for 31. Sclieideckeri, 6 for M. Malus var., 4 for M. Sargenti, 
and 2 for M. Ringo sxiblobata. This is a total of 28 below the expected 
total of 22,724 ovules for 2,244 apples having 11,362 carpels. 

In two or three cases the two ovules of a single carpel were sup- 
pressed, but for all others one of the pair was absent or so undeveloped 
that its presence could not be detected. 

The rarity of suppression of ovules is most clearly brought out by 
comparing the number recorded as suppressed with the total of ovules 
present. The 6,642 apples of all species contained 32,192 carpels, and 
with two ovules to each carpel, 64,384 would be the expected total of 
ovules. The actual number recorded as present was 64,777, but this 
included 421 ovules in excess of normal. Deducting this number leaves 
64,356, which number, if increased by 28, the total of ovules sup- 
pressed, will equal the normal for the fruits considered. For the 
apples examined, approximately one ovule in 2,300 was suppressed; 
the percentage is sufficiently low to indicate that suppression is of, 
rare occurrence. 

Comparison of Orchard and Crab-like Varieties in Ovule and 
Seed Production 

In neither size-group of orchard varieties were deficiencies in 
ovule production recorded, but in all varieties, except Collins and 
Mammoth Black Twig in both size-groups and Tolman in the small 
size-group, ovules were in excess of normal in numbers ranging 
from two for Fameuse in the small size-group and three for the same 
variety in the large size-group, to 1,528 for Shockley in the large 
size-group and 1,468 for the same variety in the small size-group. 
The variety ranking next to Shockley in number of ovules in excess 
of normal was "Winter Rambo, which had 878 in the large size-group 
and 334 in the small size-group, but this variety had more than three 
times as many large apples and nearly three times as many small 
apples as had Shockley, so that while there were 8.6 surplus ovules 
to each large apple in Shockley, there were only 1.6 surplus ovules 



11 



= *d 

Sens th 

Nos re 

bi- 

?? il. 

rd 



80 
80 



80 }) 

81 2d 

82- es 

82 

li *■ 

83; >st 



1966' 
1964- 
83! ed 



iy 

Of 



S5i 
1965: 



ne 
38 
841 es, 

19681 4.0 

84; 4Z 

19641 OV 

1964; ies 

84< ^ 

82< tly 



85^ 

84* 

1966< 



ire 



N 

ive 
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lot 
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ial 
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ers 

ers 
md 
is, 
the 
ted 
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jses 



Table 9.— Seed Pbodoction in Cbab-uxe Sph ies and Vableties of Malds 



baccata, red fruit. 
baccata, red fruit, 
■ baccata maxima . . 



Malta prvnifolia var . 



I Soulardi 

> sp. (f) Hyslop Crab. 
I »(>. ( () Yellow Sibci iai 
t spcctabilis No. 615. . . 
I Toringo 




iOB Of fruits as t 



I'l^ri'il. lit ion of fruits as to i 



SO 115 
9' 17 



-_ carpel. No. I i 
14 found | t 



24; 11, 4 



2 332 
9 436 
308 

1608 



1002 


U74 


4 250 


1350 




675 


1 193 




1584 




Kill 


849 



86.SG 

■ I I.;", 
33.02 



31.70 

ii.;./„; 
64.04 
33.52 

48.11 

43.30- 



Table 10. — Seed Phodoction in Ha:-d-E'iillinated Pbdits 



Orchard variel 
Orchard ' 
Crab-like 
Crablike 

„ ., , l Crabdike forms 

Sclfed J 0rciari varieties „i£ 



Average 




n!)""' 


Distribution of carpels 


1 A nT I 






fruit 




^i^rse" 


of good 




2 | 3 | 4 | 5 


6 | 7 


8 ™ eds |0|1|2|3|4|5|6|7|8|9|10|11!12 


13 | 11 15 


li, 


83.42 46.34 
87.37 48.21 

7.82 , 19.35 
18.42 25.31 

2.71 14.75 
60.37 39.78 


58.48 
58.99 
22.01 
29.33 
16.71 
53.11 


1 13 

6 

. 40 | 838 

5i 61 

1 


812 
839 
1492 

31 
12 


10 

9 
9 


2 

16 

4 


M 7.23 i 11 7 1 14 
■ 7.45 \ 4 8 15 
1 74 L'7 HIS 297 
J 5.69 | 3 : 8 21 
2.56 i 1 j 11 , 14 
| 5.16 111 


26 1 58 1 75 
23 1 42 80 
249 264 217 
14 17; 24 
6 9 2 


116 126 152 136 87 J 16 7 
90 ! 145 164 1 137 104 19 ' a 

191ilS4 164 137 1 64 l 1 1 4 
30 | 36 25 | IS i 8 | 2 , [ 1 

2 2 ' i ; 2 . 


I 1 I 


4 









1917] Seed Production in Apples 211 

to each large Winter Rambo apple. For the small apples the difference 
between the two was still greater. In Shockley, multiplication of 
ovules appeared as a well-established characteristic, and in this regard 
the variety is comparable with M. spectabilis among the crabs. With 
other varieties whose fruits have surplus ovules, the numbers are 
scarcely sufficient to suggest an established tendency towards multi- 
plication, but rather that their appearance is more or less casual. 
However, comparison of the records for the twenty-one orchard 
varieties (Table 7) with those for the twenty-five crabs (Table 9) 
indicates clearly that production of ovules in excess of the expected 
normal is of much more common occurrence among orchard varieties 
than it is among the crabs. 

The relative standing of orchard varieties and the wild or semi- 
wild forms of Mains in the matter of seed production is, perhaps, most 
clearly shown by comparing the percentages of ovules, actually 
present, that develop into seeds. Thus, the 4,851 large fruits of 
twenty-one orchard varieties contained 53,319 ovules and developed 
39,724 seeds, or 74.5 percent; the 4,726 small fruits of the same 
varieties contained 50,385 ovules and developed 33,940 seeds, or 67.38 
percent; or, taking the aggregate of apples from orchard varieties, 
the percentage of seeds that developed was 71.03, while for the 6,642 
fruits of species of Mains the 64,777 ovules developed 28,050 seeds, or 
43.3 percent. These percentages of aggregates, 53.3 percent for species 
of Mains and 71.03 percent for orchard varieties, show fairly well the 
relative seed-producing capacity of the two groups and are sufficiently 
separated to indicate in a positive way that orchard varieties are 
decidedly superior to wild species in seed production. 

SEED PRODUCTION UNDER CONTROLLED POLLINATION 

All fruits thus far considered in relation to seed production have 
developed from flowers open to pollination by natural agencies. That 
the insect agents did the work well and that weather agencies were not 
adverse may be assumed from the fairly full crops borne by the trees. 

The question as to whether protection of flowers and the artificial 
application of pollen gives equal or greater seed production than does 
open pollination is naturally suggested, and brief mention of seed 
production in fruits developed from protected hand-pollinated flowers 
may be made here. 

The fruits resulting from hand pollination of emasculated flowers 
protected by paper bags numbered 4,504 for the six seasons 1909 and 
1911-1915, but of these fruits there were 643 for which the record is, 
in some detail, incomplete ; these are omitted, leaving 3,861 fruits, the 
records from which are here considered. These fruits were separated 
into four groups according to parentage for the purpose of maintaining 
a distinction between and recording the behavior of the two classes 



212 Bulletin No. 203 [August, 

of apples, orchard varieties and crab-like species of Mains, when 
crossed in different ways. At this time it is not the purpose to con- 
sider these combinations further than to show carpel and seed distri- 
bution and seed averages. The four classes of crosses were : orchard 
varieties X orchard varieties, represented by 833 fruits ; orchard varie- 
ties X crab-like forms of Mains, represented by 857 fruits; crab-like 
forms of Mains X orchard varieties, represented by 1,967 fruits ; and 
crab-like forms of Mains X crab-like forms of Mains, represented by 
204 fruits. To these may be added 45 fruits resulting from self- 
pollinated flowers of crab-like forms of Mains and 12 fruits from 
selfed flowers of orchard varieties. These additional classes had small 
representation because most efforts to produce self-fertilized fruits 
have failed entirely. It is general thruout the genus Mains that 
stigmas of flowers of the very diverse forms do not readily accept 
their own pollen, and this characteristic is more commonly apparent 
among orchard varieties than it is among the less highly developed 
crab-like forms. As hybridity in plants tends strongly towards ste- 
rility, the prevalence of self -sterility in species and varieties of Mains 
indicates the probable hybrid nature of many of the forms. This, 
to the breeder, is a discouraging feature, because selfing is essential 
to determining the transmission and segregation of particular pa- 
rental characters. 

Records of carpel distribution with number and distribution of 
seeds for each of the classes of fruits resulting from controlled pollina- 
tions are brought together in Table 10. There is nothing in this 
table to indicate marked superiority in seed production of fruits 
developed from flowers artificially pollinated over fruits from flowers 
open to natural agencies for transfer of pollen. In the groups of 
naturally pollinated orchard varieties the average number of seeds 
to each fruit was for large fruits 8.27 and for small fruits 7.21, or for 
the two sizes combined, 7.85. For fruits from controlled pollinations, 
the 833 fruits of orchard varieties pollinated by orchard varieties 
had an average of 7.23 seeds to each fruit, and the 857 fruits of 
orchard varieties pollinated by crab-like species had an average of 
7.45 seeds to each fruit ; or, combining the two groups in which orchard 
varieties served as mother plants, the seed average was 7.35. These 
averages do not indicate that control of pollination exercised any 
marked influence upon seed content. Fruits of the twenty-five crab- 
like forms of Mains developed from open-pollinated flowers had an 
average of 4.22 seeds to each fruit. The 204 fruits of crab-like forms 
which resulted from hand pollinations with pollen from other crab 
forms had an average of 5.69 seeds to each fruit, while the 1,967 crab 
fruits developed from flowers hand pollinated with pollen of orchard 
varieties had an average content of 4.74 seeds to each fruit ; or, com- 
bining these groups in which the mother plants are crabs, the average 
was 4.83 seeds to each fruit. Here the averages for fruits from con- 



1917] Seed Production in Apples 213 

trolled pollinations are in advance of those for fruits from open 
pollinations, but the differences are not great, and when the disparity 
in numbers of fruits averaged in the different groups is considered, 
it appears that further investigation is needed before a stable basis for 
definite conclusions can be reached. It may be stated, however, that 
participation in the making and compiling of such records as we now 
have, together with study of the data, has given a rather definite im- 
pression that whether the pollination is open or controlled makes small 
difference in the proportion of ovules that develop as viable seeds. 

CONCLUSIONS 

1. From the foregoing study of seed production in apples it 
appears that the average number of seeds to each fruit is almost 
twice as great for orchard varieties as for fruits from crab-like forms 
of Mains. Dividing fruits of orchard varieties into two groups on 
the basis of size, it further appears that large apples exceed small 
apples in seed production, altho the difference is not nearly so great 
as is the difference in seed content between orchard varieties and crab- 
like forms. 

2. The range in average seed production as exhibited by different 
varieties is wide with both orchard varieties and crab-like forms. 

3. Departures from the normal of five carpels to each fruit occur 
with both orchard varieties and crab-like forms, but are much more 
frequent with crabs than with orchard fruits. 

4. There are wide differences among individual varieties and 
species in seed-producing capacity, and the range in numbers of seeds 
in individual fruits is also wide. 

5. The assumed normal of ten seeds to each fruit is likely to 
occur in a small percentage of orchard fruits, but rarely occurs in 
crab-like forms. 

6. Capacity to produce seeds appears as a varietal characteristic. 

7. Parthenocarpic fruits occur in orchard varieties and in species 
of Mains, but not in very great numbers. 

8. There is great regularity in the appearance of ovules in normal 
numbers, that is, two in each carpel. Few cases of suppression of 
ovules occur ; numbers in excess of normal are more common among 
orchard varieties than among crabs. 

9. Comparison of seed production in fruits developed from flowers 
open to pollination by insects and in fruits from hand-pollinated 
flowers brings out only small differences ; apparently seed production 
is not dependent upon the manner in which pollination is effected. 

10. Considerable differences appear in seed production of indi- 
vidual fruits and of particular varieties, but averages of groups 
warrant the conclusion that the more highly developed orchard 
varieties exceed crabs in seed production and that, as between large 
and small fruits, large fruits produce the greater number of seeds.