Describe Cannas: Rhizomes

It was Dr Nobuyuki Tanaka, the Japanese taxonomist, who created a set of working measurements for Canna rhizomes, and he used them to help him categorize the wild species, resulting in his Taxonomic revision of the family Cannaceae in the New World and Asia in 2001. This revision was the start of bringing order to the chaos we had previously experienced in naming of our Canna species. The categories defined by Tanaka are:

1. thick, up to 3 cm in diameter
2. thick, up to 7 cm in diameter
3. long and thin
4. tuber-like groups
5. no rhizomes
   

To the first four specified by Tanaka, we have added the fifth category. At Claines Canna we have grown C. paniculata that did not have any rhizomatic growth, and Dale McDonnell, in Australia, has had this same experience, having inherited an old Foliage Group specimen that displays the same characteristic.

We have used this classification for some years now, and we cannot find any fault with it.

Wild species tamed

It has long been the practice when writing about Cannas to assert that the species are in total disarray, nobody knows how many there are or what the hundreds of published names are synonyms of. That is no longer the case.

Dr Nobuyuki Tanaka is a botanist at the Tokyo Metropolitan University and at the Makino Botanical Garden in Kochi prefecture, Japan. He has published a full taxonic revision of the Canna species and he has identified 19 species as being distinct and separate.

In addition, the botanists at Kew Gardens have assigned all of the published species names to one of the 19 accepted species, i.e. sorted the synonyms.

References:

• The original Canna checklist at Kew Gardens can be located at: http://www.kew.org/wcsp/.

• The Wikipedia has a separate article for Canna species, containg both the accepted species, plus all of the synonym names linked to the species. That article can be found at: http://en.wikipedia.org/wiki/List_of_Canna_species and reflects both the taxonic revision and the Kew checklist.

• Tanaka, N. 2001. Taxonomic revision of the family Cannaceae in the New World and Asia. Makinoa ser. 2, 1:34–43.

Well done to everyone concerned... now if we can find a source of Canna liliiflora seed, then I'd be totally happy.

The real origins of Canna

The question has often been asked, "How can we be so sure that Cannas originated in South America?" We do know that the first Cannas introduced to Europe were C. indica L., and although they all came to Europe from the East Indies, they originated from the American continent. Charles de l'Ecluse, who first described and sketched C. indica in his Histoire des plantes rare observées en Espagne (history of rare plants observed in Spain), published in 1576, indicates this origin, and states that it was given the name of indica, not because the plant is from India, in Asia, but because this species was originally transported from America: "Quia ex America primum delata sit"; and at that time, one described the tropical areas of that part of the globe as the Western Indies; English speakers still call them the West Indies.

Much later, in 1658, Pison made reference, in his Histoire naturelle du Brésil (natural history of Brasil), to another species which he documented under the vulgar name of 'Albara' and 'Pacivira', and which resided, he said, in the shaded and damp places, between the tropics; this species is Canna angustifolia L., (later reclassified as C. glauca L. by taxonomists).

Without exception, all Canna species that have been introduced into Europe can be traced back to the American continent, and it can be asserted with confidence that Canna is solely an American genus. If Asia and Africa provided some of the early introductions, they were only varieties resulting from C. indica and C. glauca cultivars that have grown for a long time in India and Africa, but not from species growing in a spontaneous state.

The penultimate argument to the assertion that Canna is a South American genus is the fact that it is certain, as it is pointed out by Lamarck, in his Botanical Encyclelopédie, that "Cannas were unknown to the ancients, and that it is only after the discovery of the New World, that they made their appearance in Europe; whereas if the soils of India or Africa had produced some of them, they would not have waited until the 1860’s, to make an entry into the European gardens."

The final argument is that Canna seeds have never been discovered by archeologists in the Old World, and the hard shells of Canna would have ensured that some would have survived.