Y. Yulian,"fujime et N. Okuda, MORPHOLOGICAL OBSERVATIONS ON CAPITULUM INITIATION AND FLORET DEVELOPMENT OF GARLAND CHRYSANTHEMUM (CHRYSANTHEMUM-CORONARIUM L), Engei Gakkai Zasshi, 64(4), 1996, pp. 867-874
Morphological properties of capitulum initiaton and floret development
of garland chrysanthemum (Chrysanthemum coronarium L.) were observed
with a scanning electron microscope (SEM). Sixteen cultivars varying i
n flowering time were used. The flowering process was classified into
10 stages. A capitulum was initiated from stage 2 (early involucre for
ming-stage). The differentiation between ray and disc florets occurred
at stage 5 (late floret forming-stage). Disc florets has a pistil and
five stamens. Disc florets covered the entire surface of receptacle e
xcept for one or two layers of ray floret which are located on the per
iphery of the receptacle between the disc florets and the involucres.
A ray florets has a pistil, but no stamen. There were cultivar differe
nces in capitulum size, numbers of ray and disc florets, and involucre
s. The diameter of the capitulum ranged from 71.0+/-0.0 mm to 42.0+/-6
.2 mm; the number of ray florets per capitulum ranged from to 23.7+/-5
.4 to 14.2+/-0.5; where the range of disc florets was from to 478.0+/-
0.0 to 276.2+/-44.8. The number of bracts (involucres) per capitulum r
anged from 41.0+/-0.0 to 27.50+/-5.0. Individual cultivars differed in
flowering response between spring and autumn. In the spring, budding
in all cultivars occurred earlier than that in autumn. Capitulum of 'K
airyo chuba satoyutaka', 'Tatsunami', and 'Otafuku-A' became visible 1
0, 15, and 35 days after planting, respectively. In autumn, however, c
apitulum initation of 'Kairyo chuba satoyutaka' occurred 70 days after
planting. The number of nodes from the cotyledon to capitulum in the
spring was significantly fewer than that formed in the autumn. The nod
e number of 'Kairyo chuba satoyutaka' was 32.8 in the spring, and 54.7
in the autumn.