Can someone explain to me why some fruits come true to seeds and others, like avocado and mango, do not? I can't wrap my head around it.
Hi Zafra
The embryo in seeds usually consist of cells which result from fertilization. Means a pollen tube fertilized a egg cell. Most of the fruit however, (and even the seed coat and some tissue within the seed coat, the so called nucellar tissue) have a totaly different origin, as they are formed from cells of the mother plant. This is why a lemon tree always has lemons as fruit. Even when you pollinate it with grapefruit, it will still form lemon-fruit as the fruit tissue is largely maternal, and next generation cells are found within seeds only.
Lets go back to the seed. So the embryo usually consists of cells from the next generation. There are however some cells within the seed that are purely maternal (e.g. the nucellar tissue). In some plants this tissue forms additional embryos within the seeds. These additional embryos consist of pure maternal cells and are therefore clones of the mother plants. This happens in many
Citrus e.g. in most lemons. A single lemon seed will contain many embryos (it's
polyembryonic) and the many clonal embryos will outnumber the other one. Lemon seeds will therefore give you many lemon plants (clones of the mother plant) and only rarely a plant that got some characters of the pollen donor.
A few
Citrus species (e.g. pumelo) and a few cultivars (e.g. Meyers lemon) don't have this trait. They do not form additional embyos from maternal tissue, and they will therefore have regular embryos only. (These
Citrus might have a single embryo per seed only
monoembryonic, or the embryo might divide and form multiple embryos
polyembryonic). these
Citrus do not come true from seeds as the embryos, seedlings and resulting plants will have traits of the pollen donor. This case, while being rare in
Citrus, is generally much more widespead in plants.
See also:
http://en.wikipedia.org/wiki/Nucellar_embryonyAs for more plants that clone themselves via seeds see:
http://en.wikipedia.org/wiki/ApomixisThe
Citrus story in other words:
http://www.ubergardener.com/grow-true-to-type-citrus-from-seed/forum seach and google will give you many more hits.
Also I'd still love a rooting stick of meyer lemon. Does anyone know of a reliable provider?
Official budwood - is the most likely pathogen free source for cuttings in the US. I'd go for no other cuttings, in order to reduce the risks imposed on the
Citrus production of your country. Did you check whether it is legal to import cuttings to Venezuela? Did you check out the variety of other lemon cultivars coming true to seed?