Floral Structure, Sex Expression and Fruit-Set of stinkbean (Parkia speciosa Hassk.)

Abstract

The study on floral structure, sex expression and fruit-set of stinkbean (Parkia speciosa Hassk.) was conducted at Trang Horticultural Research Center in Trang province from february – July 2005. Its flower was characterized eith compound inflorescence, consisting of 1-12 capitula, average 5.21+1.17.  The capitulum had a peduncle length of 28.96±10.58 cm. A capitulum consists of many small flowers with different floral structure and function that can be divided into 3 types : staminodial flowers at the proximal end, nectar-secreting flowers at the middle, and  fertile flowers at distal end. Thesize of capitulum from staminodial flower to fertile flower was length 8.82±0.68 cm. Each part of staminodial flower, nectar-secreting flower and fertile flower was 3.91x1.58, 3.02x2.74 and 4.49x5.03.91 cm respectively. On average, the number of flower per capitulum, staminodial flower, nectar-secreting flower and fertile flower were 2,277.70±109, 132.52±529.28±26 and 1615.90±107 respectively. Each flower had 5 sepals and petals. The number of stamens in staminodial flower, nextar-secreting flower and fertile flower were 11.50±0.50, 10.8±0.57 and 10.6±0.82 respectively. Only single carpel was found in fertile flower. The size of staminodial flower, nectar-secreting flower and fertile flower were 2.54x20.03, 2.80x11.88 and  2.24x14.41 mm, respectively. The total polyads per anther in staminodial flower was 15.15±7.22, nectar-secreting flower was 79.08±5.50 and fertile flower was 111.03±4.25. In every flower, number of pollen grain in polyad was 16. The dimension of polyad of fertile flower was 91.00x67.95 micron and nectar-secreting flower 72.53x61.37 micron. The size of pistil in fertile flower, functional hermaphrodite and func-tional male were 1.08x10.94 and 0.47x6.06 mm respectively. The ovary of functional hermaphrodite flower had 16.57±2.18 ovules. The percentage of male capitula, hermaphrodite capitula and set fruit were