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
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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
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1965:
ne
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1964; ies
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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.
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