I was out with my camera today (central Spain near Madrid) and a small yellow flower caught my eye because I didn't think I'd seen it before. When I started photographing it, I noticed something odd. Three of the flowers had 7 petals but one had 8. At first I though the 7 petal flowers had maybe lost a petal each but close examination showed them to have clear 7-fold symmetry with each petal being opposide a gap between petals on the other side while the 8 petal flower had clear 8-fold symmetry.
Indeed. if you look at photo "flower7" you can see a stem in the bottom right corner with two buds on it, one with 7-fold symmetry and one 8-fold. Even more bizarre, if you look at "flower8", there is a bud to the left which appears to have 6-fold symmtery!
"flower group" showes the whole plant or plant group. I just wonder, how common is it for a plant to produce flowers with different numbers of petals like this?
Also, if you know the identity of the plant please let me know.
Just to add to the confusion, I have no idea what your plant is (Stonecrop?), or why it should produce such odd flowers but, . . . .
The Purple Mangosteen of Southeast Asia produces fruits that have varying numbers of segments. On the bottom of the fruit are raised ridges that are remnants of the stigma and they are arranged like the spokes of a wheel, The spokes correspond to the number of segments inside the fruit. I'm sure there must be plenty of other examples out there. Let's not forget the four leaf clover for example.
Have a read of this article. . . http://www.sciencenews.org/view/generic/id/7395/description/Fibonaccis_Missing_Flowers
Hope that adds something to your querey
Your plant smacks of Sempervivum/Jovibarba/Rosularia, but I can't find a match.
There are a bunch of other genera in the Iberican Crassulaceae
but of the ones with star-shaped flowers most have 5-petalled flowers (Sedum, Crassula, Villadia...)
I'd lean towards Aichryson laxa, but it has a green calyx (with 9-12 segments) and I think it is found in the Canaries and Portugal but not Spain.
I'd suggest Aeonium, but the shape of the inflorescence isn't right.
Aeonium and Monanthes are two of many genera whose species have polymerous (many-parted) flowers.
Pentamerous seems to be the base level in the Crassulaceae, but it goes up to plenty more than in your specimen, Alan. For instance, still in the Crassulaceae, have a look at this Greenovia dodrantalis - http://commons.wikimedia.org/wiki/File:Greenovia_dodrantalis_(BG_Zurich)-02.JPG
I suspect the higher the 'merous' number, the more prone the plants are to variation in the number.
There's a discussion including the evolutionary aspects of floral polymerism here
Why the number of petals varies, I have no idea. Maybe they are L'Oreal flowers - having a polymerous corolla 'because they're worth it'?
Thanks for your reply. I've tried reading the discussion at the final link but it is somewhat beyond me - I have no education in botany and I cannot read a text where every tenth word has to be looked up!
Your first link (house leeks) talks about flowers within a single genus having flowers with different numbers of petals. There is nothing in that page to suggest that the same species within a genus can have varying numbers of flowers.
Looking at the third link - A laxa - I couldn't find anything about the number of petals, only their length.
The succulent-plant.com link seemed to have all flowers with 8 petals. Did I miss something? Apart from the complete lack of succulent leaves (see my photo of the group) the flowers are very similar.
When you provided your answer with respect to polymorphism, were you thinking of plant species that can produce flowers with a different number of petals on the same individual plant?
It was this feature that I thought was most odd. My impression (and no more than that because I haven't studied the links in depth) is that the polymorphism relates to plants that have flowers with the same number of petals on any individual plant but with differences within the species.
My posting was by no means thought through; I was just sharing some thoughts.
My first three paragraphs were just trying to identify your plant.
Only the rest related to the polymorphism.
I hadn't pondered the issue of different numbers of petals on flowers of a single plant.
In a related vein, maybe there can be different numbers of petal on the flowers of a single plant as it goes through the season, though the same number at any one time.
I went back to the flowers yesterday. There was an extensive patch about 10m x 3m and all the flowers were 7 petalled. Then I found the small patch of half a dozen plants a bit further down the path. I took this photo.
In terms of identification, my wife - who is the flower expert in our family - says it is some sort of stone crop so I think your suggestions, Mike, are correct. Frustratingly she found the plant in one of her books but when I Googled the Genus and species it led to images of a very different plant.
But back to the new image. There is clearly one stem which splits into two stalks and one stalk has a 6 petal flower and the other a 7 petal flower. I find this very disturbing. Surely the two stalks have identical DNA but in that case how does the same DNA give rise to flowers that are morphologically so different. It's like finding identical twins, one of whom has 6 digits on each hand. I would really like some explanation from an expert. Can the two stalks have different DNA in which case how? If not how can identical DNA produce such different flowers?
DNA is only part of the story...
What plant looks like is controlled also by expression of genes; factors which can sometimes be influenced by particular stimuli but at other times seem rather random.
Abnormalities of plants have been studied extensively. There's a classic book on it:
Worsdell, Wilson Crosfield, 'The principles of plant-teratology', 1915
(You might also look up teratology more generally - https://en.wikipedia.org/wiki/Teratology).
From personal experience, I have seen:
- Streptocarpus with laminar enations on the leaves (platy outgrowths)
- fasciated stems on Salix and Stepahnotis
- twin-flower stems (like yours) on violets
- violets producing multiple flowers from one stem (on sub-pedicels from the bracts)
- violets and foxgloves with peloric flowers (see peloria)
- violets seed pods with just two valves (rather than three)
- maples with leaves in whorls of 3 and 4 (rather than the normal two)
- monstrous growth on cacti
With all those, there is no obvious reason for it.
But there are other situations: many insects can cause a plant to develop galls - which are the plants own cells, just abnormally developed. The insects tamper with the plant's metabolism; I don't think the DNA itself is affected.
In most of those cases, the rest of the plant has been normal.
With the sycamores, the main stem may have many-whorled leaves, but side branches may be normal.
What you are seeing with your succulent is similar.
In my list above, I mention a few perhaps unsual terms, intentionally.
If you look them up, it may open-up a world of variation to you.