Trochodendrales
| Trochodendraceae | |
|---|---|
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| Trochodendron aralioides | |
| Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: |
Trochodendrales Takhtajan ex Cronquist |
| Family: |
Trochodendraceae Eichler |
| Genera | |
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Trochodendraceae is the only family of flowering plants in the order Trochodendrales. It comprises two extant genera, each with a single species found in south east Asia. The two living species (Tetracentron sinense and Trochodendron aralioides) both have secondary xylem without vessel elements, which is quite rare in angiosperms. As the vessel-free wood suggests primitiveness, these two species have attracted much taxonomic attention.
Pollination is probably myiophyllous, even though Tetracentron shows a clear anemophilous syndrome. The pulverulent seeds are dispersed by the wind (anemochory). Trochodendron is present in both protandrous and protogynous forms that are self-compatible.
The plants are found in wooded formations, Trochodendron between 300 m and 2.700 m above sea level and Tetracentron between 1.100 m and 3.600 m above sea level.
Flavonoids (quercetin and kaempferol) and proanthocyanidins (cyanidin and delphinidin) are present. Epicuticular waxes are basically composed of nonacosan-10-ol. Tetracentron contains chalcones or dihydrochalcones. Trochodendron contains myricetin. Ellagic acid is absent.
Trochodendron and the fossil genus Nordenskioldia (to which the leaf fossils called Zizyphoides are also attributed) was present in the Lower Middle Eocene (49-50 Ma), it has been found in the Republic formation of Washington State (USA), demonstrating that the family had a wider distribution than currently.
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Wikipedia