On the self-sown pumpkin, pollinators will fail because there is nothing yet to pollinate. All the flowers blossoming are male. Many plants separate the male and female parts of their flowers in some way. For some species, this is just a separation within the flowers; for some species, it is different plants entirely. And still others take the way of the pumpkin – separate male and female flowers on the one plant. Pumpkins refine this technique a little further, with the female and male flowers on an individual plant blossoming at different times. The pumpkin vine growing in my back garden has a lot of flowers dotted along its wandering arms, but all are male. Thin stalks jutting up from the stem with a bright yellow bloom atop. The female flowers will come later. They sit closer to the stem on top of a tiny potential fruit. I say potential because it will only grow into a fruit if it is pollinated. Without pollen, it will wither and die. The plant has no reason to put effort into growing it to a full fruit if it is not pollinated because without it being pollinated, the seeds will not be viable. The plant’s intention in growing the fruit is to disperse the seeds. I use the word ‘intention’ lightly – research on plant consciousness is so far inconclusive (it’s difficult enough for researchers to define consciousness in humans and other animals, let alone plants!). The plant does not mindfully let the unfertilised fruit die and the fertilised fruit flourish. It’s just the way nature works.
By separating the male and female flowers – thus separating the sperm and eggs – the plant increases the likelihood of cross-pollination; that is, the likelihood that a seed will be composed of material from two completely separate plants, thus increasing genetic diversity. (That’s actually the biological reasoning behind all sex, including pumpkin romance.) Increased genetic diversity in seeds increases genetic diversity in future generations and thus increases survival chances of the species.
For the gardener, the separation in time and space of male and female flowers on pumpkins – and all other members of the pumpkin family (zucchini, cucumber, watermelon, rockmelon, squash, gourds) – that means it’s best to grow several plants at once. Not several plants of the broad family, but several plants of a single type. I really need another pumpkin plant or two to provide male flowers when my rambling vine is up to producing female flowers. but the season is late. Too late really for pumpkins. The nights are getting cooler and the days shorter. Even if this pumpkin plant does produce female flowers in abundance and they manage to get fertilised by those busy bees, it is unlikely they will get enough warmth to grow into mature pumpkins. But summer seems to be hanging on, so I’ll let the pumpkin ramble a little longer and see what happens.