Hi Folks, I am currently looking into the possibility of propagating the Calocedrus decurrens 'Compacta'. According to the Illustrated encyclopedia of conifers by DM van Gelderen and JRP van Hoey Smith, this tree originated at the arboretum I now work at. It is described as a leaderless and compact form. Before taking a look at our own tree I decided to look it up on the net. It is described everywhere as a dwarf and compact tree which is globe shaped and flat topped. 'Nice' I thought, 'I'll take a look at ours to see how it is getting on'. We only have one left, so after a bit of fruitless searching for a small/dwarf conifer I had to resort to looking at more detailed maps to get its exact location. Imagine my surprise when I found our one and only 'Compacta' right next to our staff room, the tree which I used to park my old motorbike under! I'd hazard a guess that it is around 20-25ft high and has a trunk at least 8ft in height before the first branches. Indeed it is leaderless and the crown is compact but a dwarf it is definitly not!! My question is, does C.decurrens 'Compacta' always reach this size or is there another, smaller form propagated worldwide with the wrong name applied? I also noted that there is a form named 'nana'. Have the two been mixed up somewhere along the line?
It is common for slow-growing conifer cultivars to be described as dwarf. How old is the 'Compacta' there? It may have taken a long time to reach the size it is now.
Compacta, Nana and Intricata are not the same in their growth habit. Then again if we look in the van Gelderen Conifers book we will see a major difference in the growth habits of the two principal trees, one being a columnar shape and the native plant for us being a much more pyramidal shape. There has been some doubt among a few people that the Libocedrus and the Calocedrus may not be the same plant anyway. Needle colors of them and the Winter coloration and in some areas trunk bark colors are not quite the same on them. It is going to be tough to sort out from the current published information how Compacta differs from Nana and how Nana differs from Intricata. I've seen Compacta that you know and I've seen Intricata from the Noble collection a few times, twice hands on and I've owned Nana. The larger sized plant of the three is Compacta, the smallest tree is the Intricata, the more pyramidal shape is the Nana. Think of Nana as looking like a native Calocedrus but much smaller in size, can get up to 12 feet, 4 meters in height in 30 years in the ground, considerably smaller still if they are container grown (about 2 meters tall in 30 years). Intricata is only going to be around 2 feet tall in 30 years in the ground and is a much denser growing plant (much shorter nodal length and more twiggy) than Nana. Both Compacta and Intricata make a globe shape and generally are wider than tall. Nana of the ones I've seen are usually slightly taller than they are wide. Can a 20-25 foot tall tree still be considered a dwarf form and that depends on who we learned Conifers from and who they felt had the better reasoning behind what was a dwarf and what was a semi-dwarf. If we look in the Hillier Dwarf Conifers book and the Welch Dwarf Conifers book we may read some differing opinions in what constitutes a dwarf Conifer. One opinion is that to be a dwarf the Conifer had to stay under 6 feet tall, 2 meters, at an age of 20-25 years, whereas the other opinion is that some Conifers can still be a dwarf even when they are 25-30 feet tall after 30-40 years of age. Also, a lot depends on whether the tree was ever grafted and whether seedlings from the selected or found cultivar came from a parent plant that never had been grafted. The issue here is that some Conifers could have come from a parent plant that had always been propagated from rooted cuttings and then germinated seed and lo and behold that 5 foot tall 25 year old specimen could yield seedlings from it that could attain heights of 20-25 feet in 20-25 years. So, if we conclude that the parent plant is a dwarf then the cultivated progeny seedlings from it must be semi-dwarf. Some people feel the so-called pureline seedlings are still a dwarf plant, whereas others felt the seedlings cannot be a dwarf by virtue of their size. Still, the seedlings are much smaller in height than the species form plants are at the same ages. It is like comparing a Fat Albert Blue Spruce to a normal Blue Spruce and then take into consideration one plant may be 20 feet tall at a certain age and the other may be 40 feet tall at the same age. Is the 20 footer a dwarf form compared to the standard and the answer is yes. But, is the 20 footer a true dwarf form and to me it is not but my opinion here does not count for much. Jim
