It’s just a pity that the seven-petaled lotus (Trientalis europaea) is actually a double-petaled flower, not a seven-petaled flower, nor a lotus.
To be fair, the seven-petaled lotus plant is quite worthy of its name. Its white or light pink flowers usually have 7 calyxes, 7 corolla lobes, and 7 stamens. , although you can add brackets after these 7 to write 5-8, but compared to the more talkative horse chestnuts, horse chestnuts, etc., it is still very moral. Please forgive me for the obsessive-compulsive disorder.
However, seven is a somewhat auspicious number, otherwise why would the Calabash Kids have seven (crossed out). It is the largest prime number within ten. This means that if a flower wants to have seven petals, it cannot simply double any number. It can only honestly add petals one by one through accumulated mutations. Therefore, there are not many flowers with a base number of seven in the plant world, and even fewer flowers can keep the promised number of seven.
We know that for plants, flowers are (metamorphosis) short branches with reproductive functions. The number of leaf primordia in each whorl on the branch determines the number of each flower part. Although most of its relatives and friends are five-flowered flowers, the fact that the seven-petaled lotus has seven leaf primordia in each round is basically genetically stable. But the larger the number, the more space these organs occupy in the flower bud, making it harder for each round to maintain a stable and consistent number. During the development of flowers, environmental differences and random changes in meristem size will affect the actual number of flowers grown, which may be more or less. This seems to be consistent with the Poisson distribution.
Because the Primrose family is a sympetal flower, that is, all the petals will be united at the base to form a complete corolla, so the seven-petaled lotus should actually be called the seven-petaled lotus. However, because the seven-petaled lotus has very few joined parts, it still looks like separate petals. Seven-petal lotus and its better-known relatives - such as loosestrife (Lysimachia) and cyclamen (Cyclamen) - are classified together in the APGIII subfamily of the generalized Primrose family in the APGIII system
(Myrsinoideae). It's not a lotus at all, but it's not a water lily or anything like that. Maybe the Chinese word "lotus" symbolizes some kind of circular arrangement of petals.