Leaves often blotched with purple in local cultivation. This is possibly an indication that it requires excellent drainage. Likewise, has been photographed growing as epiphyte (perched on larger trees) in wild.
UBC Botanical Garden and Centre for Plant Research
Join Date: May 2004
Location: Vancouver
Posts: 37
No vessels!
Great pictures Daniel!
Trochodendron araliodes can also be seen in the "primitive plants garden" in the inner courtyard of the Dept. of Botany. [Technical note: Botanists today avoid referring to any living plant as "primitive", because all living organisms are recognized as complex mixtures of primitive and advanced features. At some point the Botany garden will definitely have to be renamed!]
One of the apparently primitive *features* of Trochodendron, shared by only a few other flowering plants, is the lack of vessels in its vascular system. It relies instead on specialized xylem cells called tracheids to transport minerals and water throughout the plant body.
However, is this lack of vessels a primitive or advanced character?
Trochodendron belongs to the Asian evergreen tree family Trochodendraceae. Systematists have shown that Trochodendraceae represent a relatively early branch in the so-called eudicots (the large group that includes most species of flowering plant that were previously called "dicots").
But it is by no means near the deepest split in flowering-plant phylogeny. Because of its relatively intermediate position on the flowering-plant tree of life, we can infer that the recent ancestors of Trochodendraceae must have had vessels in their wood, and that these have since been lost. So the lack of vessels is actually an advanced (recent) feature in this family!
The only other species in this family of evergreen trees is Tetracentron sinense. Tetracentron also lacks vessels in its wood.
UBC Botanical Garden and Centre for Plant Research
Join Date: Jun 2001
Location: Burnaby, BC
Posts: 6,929
Sean,
Thanks for the compliment.
Is the move of Tetracentron from Tetracentraceae to Trochodendraceae a relatively recent phenomenon (I know, I'm being lazy, but you're the person to ask!). We still have our Tetracentron accessions listed under the old family name.
UBC Botanical Garden and Centre for Plant Research
Join Date: May 2004
Location: Vancouver
Posts: 37
Re: Trochodendron aralioides
Daniel,
Cronquist (1988) and Takhtajan (1996) both accept these as monotypic families (Trochodendraceae, Tetracentraceae), the sole families in the order Trochodendrales.
APG (Angiosperm Phylogeny Group, 1998, 2003) also recognize the order Trochodendrales, but allow the option of recognizing both families, or both under a single family (Trochodendraceae, as that has priority). This is a good example of the arbitrariness of taxonomic ranks such as 'family' and 'order' -- either scheme works here to provide a perfectly natural (phylogenetic) classification.
My personal preference would be to lump them in the same family (two monotypic families as sole members in an order seems excessively on the splitting side of the taxonomic ledger to me!). Nonetheless, 'officially' you can go either way according to APG, and this might be an easier option re: garden signage!
I'd be inclined to keep them in separate families. Agreed that two monotypic families does look like excessive splitting, but again, about the only similarity between Trochodendron and Tetracentron (apart from the tracheids-only) is the length of their scientific names and both starting with 'T'. They're about as similar as chalk and cheese, and putting them in the same family seems silly
UBC Botanical Garden and Centre for Plant Research
Join Date: Jun 2001
Location: Burnaby, BC
Posts: 6,929
Re: Trochodendron aralioides
In cultivation or in the wild? Flora of China treatment for the Tetracentraceae (PDF)
I'm not meaning to be argumentative - just pointing out that there seem to be differing accounts. I wonder why there is the discrepancy, because the weight of horticultural accounts certainly point to deciduous.
I have two Trochodendron aralioides. This past autumn brought purple blotches to leaves, spot-blotches. Lacking a micronutrient? Fungal? No sign of browning.
Trochodendron seems to get this colouration in winter in colder climates like BC and here in the UK. On my own plant, some leaves flush purple whilst others just sport purple blotches. When growth recommences in Spring, the leaves revert to green. This appears to be the case with a number of growers in the UK and is certainly nothing to worry about.
Colder and damper in winter here. I wouldn't announce it was nothing to worry about until I found out what was causing the blotches. Could be associated with a pathogenic organism, these don't automatically produce a quick collapse or other spectacular occurrence. Chronic water mold infestations, diminishing viruses and other problems that reduce plant performance are not rare. There in UK the Agriculture Ministry once tested Scottish rhubarb stocks for viruses and found dozens of them. Cleaned up plants had triple the vigor of original stock.
