I would like to grow certain plants in a self contained habitat (like cattails, fireweed, thistle, and other edible plants that are semi easy to maintain) but I read that siblings can’t pollinate each other. Which means that I can’t just grow a garden out of two of the same plant. How many plant families would it take to make sure all plants has a pollination partner?

  • You'll want to note that thistles are commonly regulated as noxious weeds, depending on species. If the species you want to eat are indeed considered to be noxious weeds, then it will be illegal for you to plant them in your garden. If a neighbor complains, you will possibly be liable for fines and/or costs for the city/town to "clean up" (i.e. RoundUp) your garden. Also ------- this sounds like a school assignment, so you may not get any answers (we, as a community, prefer that students do their OWN work). – Jurp Feb 19 '20 at 0:20
  • Thank you for that information. I am not a student, though. Too old. – user11937382 Feb 19 '20 at 0:23

Either you are using terms like "family" incorrectly or there is a basic misunderstanding here.

Plants from one species are (normally) only pollinated by other plants of the same species. Edible plants, and cultivated garden flowers, often have many different varieties within the same species - for example all the named varieties of tomatoes or roses will pollinate each other.

You may be confused by the fact that some individual plants (e.g. apple trees) can not pollinate themselves, and in some species each plant only has male or female flowers. Some other species have different male and female flowers on the same plant.

In some self-pollinating plants (for example peas) the flowers are actually pollinated before the flower buds open.

The idea of a "species" can be confusing though. For example many the commonly grown types of brassica (cabbage, cauliflower, brussels sprout, kale, kohl-rabi, etc) are actually the same biological species (Brassica oleracea) and can cross-polliate each other, even though they look quite different. But when they are grown as vegetables, you don't want them to flower and set seed at all, so that is irrelevant in practice.

To summarize all that, unless you want to grow only one single plant of a particular species, you are unlikely to have anything to worry about. Any plants that are usually classed as "weeds" will be prolific at reproducing themselves, without your help.

  • Thank you for responding. I was trying to say that I read that if two plants pollinate each other and their seeds grow, then none of their seeds can pollinate each other because the dna is too similar. Are you saying that cattails and other plants like them have both male and female organs and do not need pollination? Also, why do you not want vegetables to flower or set seed? – user11937382 Feb 19 '20 at 1:16
  • Plant reproduction is complicated compared with animals! But as a general rule, for flowering plants, the part of the flower that develops into the seeds is the female sex organ, and the pollen is equivalent to sperm. You don't want vegetables to flower if you want to eat the leaves (e.g. cabbage) and not the seeds or fruit. If a cabbage flowers, you get a flower stalk and the plant then dies, having completed its purpose in life, which is to reproduce itself, without ever producing a cabbage-sized collection of leaves for humans to eat. – alephzero Feb 19 '20 at 2:57
  • --- some plants can also reproduce asexually, by budding, growing new plants from the roots, physically breaking apart and the resulting "cuttings" rooting in the ground where they fall, etc, etc. Some species even produce things that act like "seeds" asexually, to add to he general confusion. – alephzero Feb 19 '20 at 3:01
  • Then how do farmers keep growing vegetables each year without getting the seeds? – user11937382 Feb 19 '20 at 3:02
  • Seed producers grow the plants in the ideal conditions to flower and produce seed (which are different from the ideal conditions to harvest the plants for food) and farmers buy new seed every year. Of course gardeners can do that themselves on a small scale, but for commercial growers it isn't worth the risk of the "seed plants" getting infected with viruses etc which are transferred through the seeds and reduce the quality or quantity of the crop. – alephzero Feb 19 '20 at 3:05

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