Seed production is the key factor for maintaining plant population renewal and development. Because of pollination limitations and other factors, orchids, especially rewardless ones, generally have low fruit set rates. In Rhomboda tokioi, however, the natural fruit setting rate is very high, more than 90%. Common reasons for such a high natural fruit setting rate include high pollinator efficiency, autonomous selfing, seed formation through apomixis and so on. To test these possibilities, we carried out field observations, morphological examinations, and breeding system experiments. The results showed no migration of pollinia into or out of flowers and suggested that the structure of the floral organs hinder autonomous selfing. Interestingly, the fruit setting rate of this orchid was still higher than 90% when the gynostemium was removed prior to flowering. Additionally, after hand pollination, the pollen tube stopped growing at a late stage and could not enter the ovule, indicating the seeds were produced by obligate apomixis. Morphological experiments showed that a megasporocyte first forms a chain tetrad and then develops into a mature embryo sac, while the embryo of the offspring developed from unfertilized egg cells. More interestingly, the offspring had the same number of chromosomes as the female parent. According to the existing theory of apomixis, we can infer that the reproductive model of R. tokioi is Allium-type apomixis.

种子生产是维持植物种群更新和发展的关键因素。由于授粉限制和其他因素，兰花，尤其是无回报的兰花，通常坐果率较低。在东京菱形但是，自然坐果率很高，90%以上。如此高的自然坐果率的常见原因包括传粉效率高、自主自交、通过无融合生殖形成种子等。为了测试这些可能性，我们进行了实地观察、形态学检查和育种系统实验。结果表明，花粉没有移入或移出花，并表明花器官的结构阻碍了自主自交。有趣的是，在开花前去除绞股蓝时，这种兰花的坐果率仍然高于90%。此外，人工授粉后，花粉管在后期停止生长，无法进入胚珠，表明种子是由专性无融合生殖产生的。形态学实验表明，大孢子母细胞首先形成链状四分体，然后发育成成熟的胚囊，而后代的胚胎则由未受精的卵细胞发育而来。更有趣的是，后代的染色体数量与母本相同。根据现有的无融合生殖理论，我们可以推断出R. tokioi是葱属型无融合生殖。