R. chrysanthum: 1776-1976
B.C. Potter, Port Ewen, New York
The series Ponticum - Subseries Caucasicum, is indeed a questionable series. It would seem that these species were considered unimportant and hard to place, so they were bunched together, with the claim to justification based on type of truss, and even that assumption is not entirely accurate.
Now, if we consider the magnitude of the task undertaken by those famous botanists, who developed all the series, we should be grateful for their dedicated work. Actually, the validity of the series concerned, is not all that important to us, for it is the individual species we are most interested in now.
Let's take a look at the least impressive species, from that bunched together series namely R. chrysanthum , a many named species, that was first recorded in 1776, known mostly by names and descriptions. R. chrysanthum is described in, "The Species of Rhododendron" as a small shrub of 6-12 inch, prostrate or semi-prostrate, with short ascending branches; annual growth short with perulae more or less persistent, a quite accurate description. This species is described in more detail by David Leach in "Rhododendrons of the World". Little value seems to be placed on this species both in England and America. "The stud book" does not indicate its use in breeding. In fact, it could be said R. chrysanthum did not seem to impress anyone.
Strange as it may seem this small species may be a living fossil. It is extremely rugged and can endure extremes in temperature with or without snow cover. It may be the oldest elepidote species, and it flourishes further north than any other elepidote.
Its place of origin is unknown, but there are several known factors that lend reason to the belief that this species migrated from a locale north of its present habitat perhaps during the ice age or during one of the upheavals.
In its trek southward on both sides of the Sea of Okhotsk, down the Kuril islands and traversing the tops of the Siberian and Mongolian mountains, it continues in a seemingly endless chain of R. chrysanthum .
If it were possible to determine the vast acreage covered by R. chrysanthum and the billions of individual plants, the figures would be astronomical.
If we consider the harsh climate R. chrysanthum thrives in, we must be impressed with its hardiness.
During its growing period we can conclude it is exposed to constant moisture due to its altitude, also exposure to long periods of light. One can only speculate on the composition of the medium it grows in, but it would be realistic to assume it provides sharp drainage through countless generations of decayed vegetation.
One could also visualize lush green mats of plant life, similar to bryophytes, forming a living mulch for R. chrysanthum and an ideal surface for wind swept seed to land in.
Some of the above conclusions regarding the growing conditions, found above the timber line of lofty mountains in Russia, are pure imagination.
To test this thesis bryophytes were spotted throughout a bed of R. chrysanthum , growing in a lath house.
It was found to be very successful. Liverworts were the easiest to use and broken pieces of the plants, soon sent down their hair like threads to anchor the plant and take up moisture.
Soon the entire bed was covered with the lush green thallus. Their thick succulent prostrate growth seemed to be able to draw moisture from the earth or cause a condensation sufficient to provide and keep the root zone of R. chrysanthum moist between normal periods of rain fall. During extremely hot weather the bed of liverworts seemed to emit a vapor or moisture that appeared very beneficial.
After several years the liverworts in their expanding growth started to cover the lower leaves of R. chrysanthum to the extent it was damaging both leaves and lower spreading new growth.
It was then decided to kill the liverwort mulch, which was easily accomplished by spraying the bed with a fungicide. Later it was discovered that the dead crop of liverworts had left an inch thick mulch of fibers which holds moisture quite well.
At the start of the experiment the bed contained 160 blooming age R. chrysanthum plants. After the liverwort was destroyed, it was found that 16 of the smaller prostrate type plants had been smothered. While this would seem regrettable, actually it caused a natural thinning out that provided room for the larger plants to expand.
The foremost benefit derived from this experiment was in the steady healthy plant growth, which seemed impossible prior to the experiment.
Flowering of R. chrysanthum has always been a source of constant amazement, starting as it does in late April before the frost is entirely out of the ground. Sometimes it blooms coated with sleet. The bloom ends in early July with considerable blooming in between. In fact it just may be that some bloom twice.
The fact R. chrysanthum is difficult to grow may be the reason why little interest was taken in this rugged species. As a parent it's genetic makeup has only started to be investigated and experimented with. However, preliminary experiments show that its offspring are all easy growers.
Its dwarfing ability is tremendous. Offspring set flower buds during their second year. Its ability to dominate a cross is amazing. Its color, though only a pale yellow, is pure.
There seems no end to its value as a parent, one could go on and on.
R. chrysanthum and R. maximum are destined to become the two purest and most important species in creating hardy and adaptable hybrids for the area east of the Rockies, providing the breeder employs controlled pollination and follows The Laws of Inheritance.
Several members have written the Quarterly describing the flourishing growth and blooming being achieved by B. C. Potter using the method he describes. Editor.