ANALYSIS OF ZINNIA CAPITULUM COMPOSITION

Composition Of capitula and their making by florets of zinnia (Zinnia violacea Cav.) were analyzed to improve seed production. For each cultivar, mature capitula were classified into three types based on shape. A capitulum was made of the accumulation of <20 newly opened florets per day for >15 days. The total number of florets per capitulum was 210 to 330, 220 to 290, and 160 to 240 for the two pumila double cultivars Kumamotonokagayaki and Snowball and for the pompon cultivar Purple Zem, respectively. The numbers of tubular florets were negatively correlated with the numbers of ray florets. Ornamentally superior capitula, which were the basic capitulum types for pumila doubles and pompons, had more ray florets and fewer tubular florets than the ornamentally inferior capitulum (the single-flowered type). Results indicate that maintaining a high percentage of plants with double-flowered capitula may decrease seed yield.