Restricted to an area around 50 kms east to west and maybe 100 kms north to south. Not road kms . . . but crow kms, if of course you could make a crow fly in a straight line. The distribution is centred around the Tropic of Capricorn in central Qld. Major towns near the area are Rockhampton, Yeppoon and Mt Morgan. It reportedly grows within the army land reserve of Shoalwater Bay.
If you are able to find a cliff line or a bunch of big rocks you may be lucky enough to see var. capricornicum in the wild. But do not hold your breath, because this is not an easy one to observe au natural. It is particularly associated with a series of quite daunting volcanic plugs that dot the dry and flat plains country in the district. Tramping around on those peaks is not for the feint hearted and nearly all of them are fenced off behind private property.
Variety capricornicum is, in a nutshell, uncommon simply because available rocky habitat, expansive enough to be safe from bushfires, is in itself quite hard to come by. It does not grow on trees so far as I am aware.
Variety capricornicum is variable in growth forms. Flowering sized pseudobulbs can be as little as 150mms long. At the time of description, around the mid 70s, it was thought that this was a diminutive form in the vane of var. pedunculatum. But I have seen them up to 300mms in the wild. In cultivation, under the spell of a good grower, it will make 350mms. They tend not to have thick bulbs.
The leaves are where var. capricornicum plants are more easily recognised. When considered in relation to the pseudobulb, the leaves are undersized for any variety of D. speciosum. When you stand back and look at a specimen plant, this aspect will be readily seen. Some times the appearance is quite odd, with the leaves looking as if they should adorn a half grown seedling instead of an adult flowering specimen. As well, the leaves are quite brittle as a rule and if you attempt to bend them very much at all they will simply snap or split.
The first thing to comment on regards the flowers of var. capricornicum concerns the flowering season. Under bush house conditions, you are likely to see fully open racemes any time from April through to September. I would assume that this same feature would occur with wild populations as well. Even as I write this piece now in mid November 2012, I have a plant in advanced bud in the bush house. It will be open by the end of this month.
No one can say for certain why var. capricornicum has a haphazard attitude to its flowering season. There is nearly always a capricornicum blooming in my bush house right through winter. There is something of a peak during the spring however.
Shape is mostly unremarkable but I have one or two that are vastly superior to the typical shape. One I call White Caps is just brilliant. There is also the well-known Big Boy clone, which has a HCC award and is truly a good form. Colour ranges from pale yellow which is very uncommon, to off-white to pure white. I have one plant that is a total albino, the only one I have heard of. This one will get special attention in my breeding plans over the years to come.
Raceme length is also surprising. These can be very long; a shade over 2 feet or 600 mms. These look outlandish when seen on the typical shortish canes of var. capricornicum. The flowers can be either typically arranged or quite widely spaced out, but never crammed onto the raceme.
Variety capricornicum is not well known in cultivation. It has not been observed by many people in the wild at all for that matter. The lack of accessible habitat makes it the second least observed variety after var. carnarvonense.
I have used it in my breeding programme because the great hope is to extend the flowering season of D. speciosum. I have specimens of plants in which Big Boy is a parent but these flowered in the spring along with all the other Speciosums. Not a lot of experimentation has taken place but it seems likely to me that some sibling crosses will flower out of season in the future if there is var. capricornicum in the background.
Variety capricornicum is one variety I think it best to pot into smaller grade bark. I have found that it does not perform well when put into course bark. In the wild, it is subject to quite dry conditions and heat. It does not seem to grow in shady areas at all, just sun-baked rock face in the main. Medium grade bark and less watering then you would give to other varieties seems to give me better results with var. capricornicum.
Light plays a big role also. If you give var. capricornicum too much shade it is much less likely to bloom for you. The stronger the light the better your flowering will be. If you live in a locale where frosts do not occur then very strong light is the best way to go. Almost full sun would be what I would provide if I had my way. Alas, I live in a frost-plagued environment and cannot do this. But flowering is achieved with reasonable regularity.
Variety capricornicum is worth cultivating simply because it is a bit quirky and has a widely extended flowering season, giving you a splash of colour when there is no other speciosums around.