ABSTRACT
The genus Primula consists of about 550 species, most of them growing in the highlands and mountains of temperate Europe and Asia. Of high commercial value are the hybrids of P. elatior and P. vulgaris. Inflorescences of P. elatior and related cvs are umbellate, with a stalk up to 20 cm long. Flowers of P. vulgaris grow singly on 6 to 12 cm long peduncles. The annual P. malacoides Franch. is native to Yunnan and northern Burma, growing at an altitude of 2000 to 3000 m. Flower stalks are up to 40 cm long and produce 1 to 6 whorls of 4 to 20 flowers. Flowers are up to 3 cm in diameter. According to Post, flowers are produced at 10°C independent of photoperiod. However, LD inhibits flowering. LD delays initiation and days to visible bud. Ten days of optimum temperature are sufficient for flower initiation in cv ‘Schneewittchen’.
