Friday, 25 May 2007

The tiger wins the stripe award

Canna 'Bengal Tiger' is a variegated Italian Group canna cultivar; plant height 190 cm; foliage height 140 cm; upright stems and gently spreading leaves; ovoid foliage, background of green (RHS 137A); veins variegated yellow (mostly 13B), but paler in places (13D); maroon edge to leaf; staminodes, labellum and stamen bright orange (28B) blushed a darker, reddish (32A) in places; yellow (15A) on edges; stigma deep orange-red; petals strongly flushed red. The flower has a crumpled silk appearance; seed and pollen has very low fertility levels; rhizomes thick, up to 3 cm in diameter. It is a mutation, as are all variegated Cannas, believed to be a sport of C. 'Wyoming'.

There were also a large number of very similar cultivars, many were obviously identical and just synonyms. But synonyms of what?

In 2005, at Claines Canna, we decided to grow as many of these plants as we could obtain alongside each other, to establish once and for all if they were different. We obtained specimens of:
  1. Canna 'African Yellow' from Holland
  2. Canna 'Bengal Tiger' from Philippines
  3. Canna 'Pallida Variegata' from Holland
  4. Canna 'Panaché' from France
  5. Canna 'Pretoria' from UK
  6. Canna 'Pretoria Dwarf' from USA
  7. Canna 'Striata' from RHS, Wisley
  8. Canna 'Striped Wonder' from USA
  9. Canna 'Tropicanna Gold'TM from UK
All of the participants in the trial were grown in identical conditions in 20 litre pots filled with Murphy's peat based, general puropose compost. They were grown alongside each other but moved around regularily to allow direct comparisons with each other, and they were all on the same automatic watering system. None enjoyed any growing advantage over the others.

It was noted that all of the individual specimens had variations in colours, both foliage and blooms. Not normally noticed, but when closely examined they became obvious. The colours in the foliage varied, and the size of the stripes was also variable. The flower colours varied considerably, having a base of bright orange, and some with orange-red blush or even markings and many had a yellow rim or even a widish border.

What was also noted was that the variations were not only across different specimens, but on the same plant! The size of the staminodes was also variable, even on the same stem!

Although claims for C. 'Tropicanna Gold'TM are for a large amount of golden yellow around the edges of the blooms, we never noticed enough yellow to justify the claim that it was different from the others, but C. 'African Yellow' was impressive on that score, and had a a yellow rim on all the flowers it produced. Canna 'Pretoria Dwarf' was the same height as all of the other trial participants, and that name seems to be misleading.

Our conclusion was that they were all the same plant, just many different names and a propensity to be variable, as are so many of the Italian Group, where the introduction of the wild species C. flaccida created a volatile mix. As this is reputed to be a mutation of C. 'Wyoming', it is not surising that it is a little unstable. The other possibility was that it may be vulnerable to the quantity and quality of sunlight and water when the foliage and flowers were being formed.

Next, we examined Canna history to establish what was the correct name for this cultural wonder. Investigation revealed the cultivar originated as C. 'Bengal Tiger' at the Agri Horticultural Society of India, Bengal in the 1950s, probably as a result of the Radiation experiments that took place at that time.

It was later transported to the African continent, by Sydney Percy-Lancaster, the Secretary of the Society, when he retired to Rhodesia, taking with him the Alipore Canna collection, originally founded by his father in 1890. Hence the synonym of C. 'Pretoria' when it was later discovered by US plant collectors in the late 1960's growing in that contintent; in spite of having already been imported directly to the USA from Bengal, India in 1963 by Glasshouse Works, again as C. 'Bengal Tiger'.

Under the synonym of C. 'Striata' it was awarded the 'Award of Garden Merit' (AGM) in the 2002 Canna trials held at RHS Wisley, but that name belongs to an early Foliage Group cultivar dating from 1868, and still being grown under that name in Europe.

The list of synonyms (probably incomplete) that we have discovered for for this cultivar are:
  • Canna 'African Yellow' - confined to Europe
  • Canna 'americanallis var. variegata' - confined to USA
  • Canna 'aureo-striata'
  • Canna 'Damascus Road' - confined to Southern USA
  • Canna 'Imperialis'
  • Canna 'Kapit'
  • Canna 'malawiensis variegata'
  • Canna 'Pallida Variegata' - confined to Europe
  • Canna 'Panach'
  • Canna 'Panaché' - confined to France.
  • Canna 'Pretoria'
  • Canna 'Pretoria Dwarf'
  • Canna 'Striata' - this name belongs to an early cultivar from 1868, still being grown in Europe.
  • Canna 'Striped Wonder'
  • Canna 'Tropicanna Gold''™
  • Canna 'Zebra Summer'
  • Canna 'Zebra Sunset'

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