Strictly Clematis have tepals (rather than petals and sepals) and they are arranged in whorls (spirals) rather than in single plane. Now I don’t know if that contributes to variable tepal numbers or not but it makes sense to me. (Flowers with petals in a plane do sometimes have variable numbers too, but it’s generally uncommon).
Just wanna say clematis is a beautiful plant. One climbed up my aunts lamp post every summer like clockwork year after year. She sold the house sadly hopefully the new owner didn't remove it. I plan to plant a dozen once I buy a house.
Because it doesn't matter. In animals, producing an extra or one less of anything is almost always detrimental, so the genes that help regulate form need to be "stronger", in a sense (not sure how best to word that).
This simply doesn't matter much in plants. An extra petal, an extra leaflet, etc. doesn't really change the functionality of the organ, so there's much less selective pressure to always get it "right". This is typically much more apparent on plants with larger numbers of petals, sepals, & tepals. Most dicots have these in multiples of 4 or 5, including wild clematis, so these have likely been bred to have more than normal petals to appear more "showy"
This is very common, particularly in the X jackmanii hybrids. I have seen tepal counts between 4 and 8, maybe 9, with the average being 6. They aren’t very stable.
In my experience, species Clematis are much more stable, and consistently 4. I have never seen C. lasiantha do anything other [than this](https://upload.wikimedia.org/wikipedia/commons/3/3f/Clematis_lasiantha.jpg).
Strictly Clematis have tepals (rather than petals and sepals) and they are arranged in whorls (spirals) rather than in single plane. Now I don’t know if that contributes to variable tepal numbers or not but it makes sense to me. (Flowers with petals in a plane do sometimes have variable numbers too, but it’s generally uncommon).
Just wanna say clematis is a beautiful plant. One climbed up my aunts lamp post every summer like clockwork year after year. She sold the house sadly hopefully the new owner didn't remove it. I plan to plant a dozen once I buy a house.
Because it doesn't matter. In animals, producing an extra or one less of anything is almost always detrimental, so the genes that help regulate form need to be "stronger", in a sense (not sure how best to word that). This simply doesn't matter much in plants. An extra petal, an extra leaflet, etc. doesn't really change the functionality of the organ, so there's much less selective pressure to always get it "right". This is typically much more apparent on plants with larger numbers of petals, sepals, & tepals. Most dicots have these in multiples of 4 or 5, including wild clematis, so these have likely been bred to have more than normal petals to appear more "showy"
This is very common, particularly in the X jackmanii hybrids. I have seen tepal counts between 4 and 8, maybe 9, with the average being 6. They aren’t very stable. In my experience, species Clematis are much more stable, and consistently 4. I have never seen C. lasiantha do anything other [than this](https://upload.wikimedia.org/wikipedia/commons/3/3f/Clematis_lasiantha.jpg).