2 BULLETIN 7 4, HAWAII EXPERIMENT STATION 
The Hawaii Agricultural Experiment Station has been conducting 
experiments with the edible passion fruit since 1924. The first of 
these was started at the central station in Honolulu, but field experi- 
ments have also been carried on at the Kona substation, Island of 
Hawaii, since 1931. In addition, many small field tests have been 
made in cooperation with growers in various parts of the Territory. 
Botanical classification, habits of .pollination, propagation, and 
general cultural requirements have also been studied by the station 
(12, p. 23; 17)} 
BOTANICAL RELATIONS 
All passion fruit species belong to the genus Passiflora. They are 
woody, perennial climbers indigenous in tropical America. Most 
Passifloras are ornamentals, but a few are cultivated for their edible 
fruit. The edible fruit is similar in form to that of certain kinds 
of melons and of the papaya. Striking examples are the giant 
granadilla, muskmelon, and the common round-fruited papaya. 
Early botanists recognized them as of the same great family. Pos- 
sibly for other reasons, however, they are now classified in separate 
families — Passifloraceae, Cucurbitaceae. and Papayaceae, respec- 
tively. Practically all species of the genus Passiflora are character- 
ized by either entire or lobed leaves arranged alternately at nodes 
along the stem and branches and have simple tendrils from nodes 
to hold the growing plants in place. The flowers are conspicuous 
because of unusual form and varying combinations of beautiful 
colors. The different kinds of edible passion fruit are not only at- 
tractive in form and color but are generally pleasing in flavor. The 
species having edible fruit, now growing in Hawaii, are as follows: 
Purple passion fruit (Passiflora edulis}, yellow passion fruit (P. 
edulis forma flavicarpa), 2 sweet granadilla or waterlemon (P. ligu- 
laris), giant granadilla (P. quadrangularis) , bell-apple (P. lauri- 
folia), West Indian sweet calabash (P. rrwliformis), red-fruited 
passion vine (P. foetida), green-fruited passion vine (P. ciliata), 
white-flowered passion vine (P. alba), and inkberry (P. suberosa). 
The last four mentioned have little, if any, value for human con- 
sumption but are eaten and disseminated by birds. The maypop 
(P. incarnata) is mentioned as of early introduction to Hawaii by 
Hillebrand (8, p. 139), but no recent reports have been noted. 
POLLINATION HABITS AND UNFRUITFULNESS 
Several species of Passiflora are irregular in their habits of setting 
fruit in Hawaii. This is attributed to unsatisfactory pollination. 
These species are evidently not in an environment similar to that in 
which they developed in their native land. 
The flowers are unusual in form, attractive in colors and odor, and 
contain an abundance of nectar indicating that they depend con- 
siderably upon live agencies to assist in pollination. The nectar is 
so located that only certain kinds of pollen carriers, such as carpenter 
bees (Xylocopa varipuncta), a species of bumblebee; large moths; 
1 Italic numbers in parentheses refer to Literature Cited, p. 22. 
2 The yellow passion fruit was identified by E. P. Killip from specimens and photo- 
graphs sent him bv the Hawaii Experiment Station as a yellow-fi'uited form of Passi- 
flora edulis. Later it was described as Passiflora edulis forma flavicarpa by Degener 
