Wednesday 20 July 2011


Why don’t seedless grapes have seeds?  How do they reproduce if there are no seeds present? Even the term 'seedless fruit' is misleading as a fruit is defined as a swollen ovary of a plant that contains seeds.

Although plants traditionally produce seed in order to reproduce there are some notable exceptions to this rule.  Seedless varieties of fruit are produced when normal fertilisation of plants does not occur. Some plants produce fruit without fertilisation in a process called pathenocarpy, translated literally as virgin fruit. This means that fruit is produced without the fertilisation of ovules and therefore the fruit is seedless. Other 'seedless' fruit may be produced after pollination occurs in a process called stenospermocarpy, where the ovules or embryos abort before they can produce mature seed.  Small seeds are produced in this case, but are immature and lack a hard seed coating.

'Seedless' grapes are a result of stenospemocary and contain small, immature seeds.  The flowers are pollinated but the seeds inside the ovule do not develop to maturity and stop developing at an early stage.

Naturally occurring mutations, genetic selection and manipulation has led to an increased variety of seedless grapes being produced as there is a high commercial demand for these fruits. Botanists and scientists hunt out valuable seedlings that may have a commercial value, looking for disease resistance, taste quality and plants that are easy to grow.

As there is no viable seed to plant most grapes are propagated through vine cuttings, which are grafted onto root stock to form new (identical) plants.  Alternatively, embryo rescue tissue culture may be used where these young seeds are grown on to produce a mature plant. This creates a cloned replica of the parent plant.

For related articles click onto:
How do seedless fruits propagate
Vegetable crop rotation
What is the difference between a vegetable and a fruit?
What is the difference between a marrow and a courgette?
What is the difference between a peach and a nectarine?
What is the difference between a yam and a sweet potato?

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