210 
somewhat expensive for a tree whose 
period of profitable production is so 
biied.? 
The other way is to breed a race of 
papayas which will carry both male and 
female flowers on the same tree, or 
which will bear perfect flowers which 
furnish the pollen needed for the ovaries 
on the same tree. A race of this sort 
could be propagated from seed, and 
there would be no loss to the grower 
through the production of non-fruiting 
males, as at present. Every tree would 
be fruitful, just as is the case with the 
apple, pear, and most fruits. 
The production of a hermaphrodite 
race like this is made possible by the 
fact that such trees exist in nature. 
The male flowers are not invariably 
confined to one tree and the female to 
another, but a dozen or more types of 
tree can be recognized; and these types 
form a precious material for the plant 
breeder. They have been described at 
some length in Bulletin No. 32 of the 
Hawaii Experiment Station;“but 1 shall 
mention the more important here. 
TYPES OF TREE 
Form 1. The first form to be considered is 
the ordinary female or pistillate tree of the 
dioecious stock. The female tree produces 
flowers exclusively pistillate, with no indica- 
tion of even the remnants of stamens (Fig. 8). 
The ovaries and the resulting fruits are of 
various shapes, inclining to the obovoid, with 
a diameter somewhat shorter than the major 
axis, and the surface smooth or only slightly 
ribbed. The fruits are usually borne singly 
on very short peduncles in the axils of the 
leaves. 
Form 2. The male tree (Fig. 12), the counter- 
part of that just referred to, produces only 
staminate flowers which, however, possess 
rudimentary or abortive pistils (Fig. 11), and 
hang in great profusion in cymose panicles on 
peduncles 2 to 5 feet in length. The flowers, 
unlike those of the female tree, have a long 
corolla tube in the throat of which are 10 
stamens arranged in two series, the one having 
slightly longer filaments than the other. At 
the base of the tube may be found a small 
rudimentary pistil, quite devoid of any stigma. 
The Journal 
of Heredity 
Since all the flowers are of this type the tree 
abounds in pollen, but produces no fruit. 
In foliage and habit, other than as described, 
it resembles the female, and is indistinguishable 
until flowers appear. 
Form 3. Correae of Solms-Laubach.* This 
form is a departure from the last and is illus- 
trated in Fig. 11. It is identical with the tree 
just referred to except that a few of its flowers 
have pistils capable of fecundation. The rays 
of the stigmas may be perfectly formed or one 
or more may be aborted, giving rise to an 
unsymmetrical or gibbous fruit in which the 
corresponding portions of the placenta have 
failed to develop. The ovaries of the well- 
formed hermaphrodite flowers incline more to 
the elongated and cylindrical form than those 
of the pistillate tree and result in correspond- 
ingly different fruits. The corolla. tube is 
elongated as in the staminate flowers and the 
stamens are similarly located in the throat of 
the corolla, being brought into proximity with 
the stigmas. These bisexual flowers are larger 
than the staminate but in other respects are 
similar, except as has just been indicated. 
The number of such flowers varies from few 
to many, there being at times as many 
forming fruits on the long pendulous peduncles 
as are to be found on some pistillate 
trees, notwithstanding the fact that many have 
fallen. Often as the fruit develops the peduncle 
is not strong enough to sustain the weight and 
breaks off, such long fruit-stems inviting 
disaster from the winds. 
Form 4. Elongata, a hermaphrodite papaya 
(Fig. 9). This tree produces two types of 
flowers. One of these types is hermaphrodite 
and is in every way similar to a well-formed 
bisexual flower on the Correae form (form 3), 
except that it usually is larger and its pistil 
is more elongated. The other type of 
flower is staminate and is identical in appear- 
ance with the staminate flowers already de- 
scribed. Because of the presence of these two 
types of flowers, this form has been referred to 
in the earlier publications of this station as the 
monoecious papaya.? 
As experiments have proceeded, however, it 
has been discovered that the pollen from such 
staminate flowers, except in the case of one 
tree, has failed to fecundate any pistils up to 
the present time, and it has been applied to 
every type of pistil found in the station collec- 
tion. Since these flowers apparently do not 
function it seems incorrect at present to apply 
to this form of the papaya the term monoecious. 
They may rather be termed either pseudo- 
monoecious or hermaphrodite. 
Form 5. Sterile hermaphrodite. 
Form 6. Forbesi of Solms-Laubach. Briefly 
2It has recently been observed at Miami, Fla., that the papaya degenerates rapidly when 
propagated by grafting. 
Grafted plants of the third and fourth generations from the original 
seedling of the Simmonds variety develop to a height of 3 or 4 feet only, produce a few small 
fruits, and are always yellowish and sickly in appearance. ] 
The papaya would appear to be a promising subject for 
grafting may have to be abandoned. 
experiments on degeneration in asexually reproduced plants. . ‘Oo i 
houses and should prove a most interesting plant for physiological experiments.—The Editor. 
?Die Heimath und der Ursprung des cultivirten Melonenbaumes, Carica papaya. 
Ztg., 47 (1889), Nos. 44-49. 
4 Hawaii Sta. Rpts., 1910, 1911, and 1912. 
On this account, propagation by 
It can easily be grown in green- 
Bot. 
