a). When seeing photos of world maples I sometimes find the similarity between species A from A' region and species B from B' region. So, I would like to refer to the questions.
1. Examples of similar species from different regions
| ssp. caudatum from China to Himalayas ssp. ukurunduense from Northeast China to Japan Acer spicatum from North America | |
| Acer palmatum, Acer japonicum etc. from Japan Acer circinatum from N.America | |
| Acer rubrum from N.America Acer pycnanthum from Japan | |
| Aacer rufinerve from Japan Acer pencylvanicum from N.America | |
| Acer miyabei from Japan Acer campestre from Europe |
Examples mentioned above associate us with the origin of maples and history of the earth, the process up to the present shapes.
2. Examples of different species living together within the same region
This means that "various species live together within each other's range without hybridizing". One of the reasons is regarded as the fact that "the timing of flowering is different between these species" and "apparently are incapable of exchanging genes under natural conditions". In the document No.4 are mentioned the following samples.
| Acer pseudoplatanus and Acer platanoides | |
| Acer saccharum and Acer rubrum | |
| Acer micranthum, A.mono, A.rufinerve, A.sieboldianum | |
| Acer diabolicum, A.nipponicum, A.carpinifolium | |
| Acer japonicum, A.shirasawanum, A.mono, A.palmatum A.argutum, A.crataegigolium |
Of course, there is a possibility of causing the hybrid species between the closely related species in the natural species. Especially in Europe and America a lot of hybrid species and cultivated species have been made by the artificial hybridization.
b). According to the document No.4, the following description can be seen as a character of maple distribution, namely "widely distributed but nowhere abundant".
c). The fact that almost all species of maples are distributed in the Northern Hemisphere. On other plants I don't know at all. According to the document No.4, " in Indonesia they cross the equator on Java and some of the lesser Sunda Islands". Acer laurinum Hasskarl(1843) is found in the mountains, 1000m-2000m above sea level. Leaves of this species are ever green and oblong in shape. This fact is also interesting to me.