Genetics of Flower Color in Asy stasia gangetica, Linn . 1 
H. Kamemoto and W. B. Storey 2 
Asystasia gangetica, Linn., also known 
synonymously as Justicia gangetica , Linn, and 
A. coromandeliana , Nees. (Alston, 1931) is a 
procumbent, clambering herb of the plant 
family Acanthaceae. It is commonly called 
"zigzag plant" from its habit of growth. It is 
indigenous to the tropics of the Old World 
from Malaya to Africa. 
The time of its introduction into the Ha- 
waiian Islands is unknown. From a few scat- 
tered plants of 20 years ago, it has multiplied 
rapidly and become widely distributed through 
the island group. It flowers and sets seeds 
profusely under a wide range of environ- 
mental conditions, from wet to dry and from 
sunny to shady. It grows luxuriantly in partial 
shade, which has led to its adoption as an 
ornamental plant for growing around build- 
ings and along fences. It is propagated vege- 
tatively very easily by means of cuttings. 
Purple appears to predominate among the 
flower colors of wild plants of A. gangetica in 
the Hawaiian Islands, but white and yellow 
are also to be seen. Plants with pale purple, 
white, yellow, and pink flowers are recorded 
in the literature (Hooker, 1885; Bailey and 
Bailey, 1946; Bailey, 1942; Neal, 1948). The 
occurrence of a number of variants in color 
of flower, and the ease of propagation and 
culture make the species a favorable subject 
for a genetical study of flower color. 
1 Published with the approval of the Director of the 
University of Hawaii Agricultural Experiment Station 
as Technical Paper No. 301. Manuscript received De- 
cember 16, 1953. 
2 Assistant Horticulturist and Horticulturist, Uni- 
versity of Hawaii Agricultural Experiment Station. 
A. gangetica has leaves that are opposite, 
exstipulate, and ovate to cordate with the 
margins entire. The inflorescence is a terminal 
raceme 5-12 cm. in length, ultimately bearing 
10 to 15 flowers. The flower is gamopetalous, 
with an inflated tube and an expanded limb. 
The tube is straight, and about 2.5 cm. in 
length. The limb comprises five lobes, and 
measures about 3 cm. across. There are four 
epipetalous stamens which are inserted in 
pairs on the tube about halfway between the 
base and the throat. The ovary is superior. 
It develops into a 2-celled, 4-seeded capsule 
about 2.5 cm. in length, which when mature 
dehisces with explosive force, usually around 
midday. The seeds are dark, thick-coated, 
flattened, and more or less circular in outline 
measuring about 4 mm. in diameter. 
Excepting in those flowers which have pur- 
ple coloration on the outer epidermis of the 
limb extending into the dorsal portion of the 
corolla tube, the tube is pale yellow. Even the 
white flower which has a white limb has a 
pale yellow tube. In flowers that have the 
inner epidermis of the corolla limb colored 
purple, the median lower lobe is darker than 
the rest of the limb. 
MATERIALS AND METHODS 
Several different flower color types were 
gathered from a number of localities in the 
vicinity of the city of Honolulu. These were 
grown in the greenhouse and used as parents. 
Descriptions of the flowers of the parental 
plants follow: 
1. Yellow with inner epidermis of limb 
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