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Vol. 11(7), pp. 11-16The McAllen International Orchid Society JournalJuly 2010

Cypripedium calceolus and A Few Close Relatives

F. Campbell & R. J. Ferry

Fig. 1. Cypripedium parviflorum var. pubescens. R. Ferry; USA; Georgia; White County; in mixed oak-pine forest. (mis-identified and filed as Cyp. calceolus var. pubescens) Photo: 35mm transparency; 26 April, 1981

In late April, 1981, one of us (RJF) was botanizing in the woods of White County, in northern Georgia, and photographed a large plant (Fig. 1). At the time was identified (actually mis-identified!) as Cypripedium calceolus var. pubescens (Willd.) Correll, Bot. Mus. Leafl. 7: 14 (1938), and confirmed as such by the literature at hand (Hawkes, 1965; Luer, 1976). Accordingly, a herbarium specimen was duly filed at North Georgia College in Dahlonega, Georgia. The plant was described by Linnaeus as Cypripedium calceolus L., Sp. Pl.: 951 (1753), and as more was learned about the range of this species it was determined that although it had relatives in the Western hemisphere, they were not the same species! Salisbury had recognized a different species in 1791, but this had been modified by Hultén in 1938, and Hultén's identification had been widely accepted in the US. The situation was confusing, but as references became more easily accessed (partly due to technological advances including the increased employment of computers), Correll's 1938 identification based on Hultén's mistake was reduced to being a synonym. Thus the US species became properly recognized as Salisbury had published in 1791. To paraphrase Dr. Greig Russell, botany is, indeed, a long conversation!

Fig. 2. Map showing the frequency of Cypripedium species in Scandanavia. Map #140610-3; Fred Campbell

So what, in reality, is the situation? In Europe, Cypripedium calceolus is often called the European/Eurasian Lady's Slipper Orchid. The most northern colony is in Sweden at 67° 32' N. which is above the Arctic Circle (66° 33' N.), and as far south as the Pyrenees and French/Swiss Alps and Italian Dolomites, around 42° N.; on the same latitude as the northern parts of the Great Lakes, as well across Russia. It was first recorded around 1568. The two American relatives; Cypripedium parviflorum var. parviflorum and var. pubescens are regarded as distinct species from the European relative. The distribution latitudes of C. parviflorum var. parviflorum does somewhat coincide with the European Ladies Slipper although C. parviflorum var. parviflorum extends down to the Southern US States and somewhat southwest. The distribution of Cypripedium parviflorum var. pubescens is more to the Mid West and northeastern parts of the US. One of us (FC), living in Sweden, supplied a map showing sites of Cyp. calceolus in Sweden, and the countries of Norway on the North Sea, and Finland, much of which is on the east side of the Gulf of Bothnia (Fig. 2).

Fig. 3. Distribution of Cyp. calceolus in Russia & adjacent countries.

A map of the Soviet Socialist State of Russia, prior to its breakup, shows the distribution of Cyp. calceolus from what is now Estonia, Lithuania and Latvia clear across Russia to the Sakhalin Island north of Hokkaido, Japan, and to the Kamchatka Peninsula and the Kurile Islands (Fig. 3).

Fig. 4. Polar projection map showing ranges of four Cypripedium species. Map #140610-4; Fred Campbell

Fig. 5. Digital labeled Cypripedium calceolus 'group 294.' Fred Campbell; Kristianstad, Sweden

Cypripedium calceolus is a Eurasian species. Cyp. parviflorum var. parviflorum is basically Canadian and in part of the northern US. Cyp. parviflorum var. pubescens is essentially in the northeastern US, but it extends into some southern and western states. A polar projection map is probably one of the best ways to illustrate the ranges and overlap areas of each of these three species (Fig. 4) (Fig. 5).

Fig. 6. The large yellow lady's slipper. Cypripedium parviflorum var. pubescens. 35mm transparency; The Bruce & Grey Counties, Ontario, Canada; June, 2003.

Fig. 7. The northern small yellow lady's slipper. Cypripedium parviflorum var. makasin. 35mm transparency; The Bruce & Grey Counties, Ontario, Canada; June, 2003.

Both the large and small yellow lady's-slippers are known in both Manitoba and Ontario, Canada (Fig. 6) (Fig. 7). The large has a delicate rose-like fragrance and its pouch is wider ( shallower) for its depth than its smaller relative.

Ripe seeds of Cypripedium calceolus have a period of dormancy that can be interrupted by chilling them. In nature they may germinate as much as a year after ripening. Mamaev et al (2004) found that about 1% of the seeds germinated about 11 months after sowing under natural conditions.

Development is slow. During the first year , the protocorm has a roundish shape, and then the mycorhizome appears, consisting of two internodes, each bearing a scale leaf and two adventitious roots. The third root grows out in the second year. The first foliage leaf appears in spring of the third or fourth year, and the rhizome growth becomes sympodial. A two-year-old root may have a length of up to 50 cm with a diameter of about 0.6 cm. Two or more large leaves appear in the fifth year, and the rhizome becomes thicker. In nature, flowering begins after the eleventh year, but may be delayed for as long as the 15th to the 17th year. Under optimum cultural conditions, more rapid development has been experienced, with plants maturing and flowering at about the eighth year.

Given the foregoing lengthy period for development of a mature plant, and its widespread root system, it is obvious that relocating these plants is not only a difficult task, but one that is more likely to result in the plant's death rather than its survival. This brings to mind the obvious need for preservation of the habitat! There is, of course, the option of culturing plants and transplanting large "plugs' of plants-and-substrate, but this is a long-term operation!


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Copyright © 2010 F. Campbell & R. J. Ferry