Doubts about Passiflora ×caponii

Leslie A. King

27 Ivar Gardens, Basingstoke, RG24 8YD, UK.

The first reported cross of P. quadrangularis and P. racemosa was made in 1953 [1]. Named P. ×caponii after Mr W. J. Capon, a member of the staff at the John Innes Institute in the UK, this cultivar was also known as P. ‘John Innes’. Cytological examination showed that P. ×caponii was a triploid. The main features of

P. ×caponii, as reported by Beckett [1], are: stems angled, leaves trilobed 13 to 18 cm long by 19 to 25 cm wide occasionally one or both lateral lobes are reduced or missing, petioles 3 to 6 cm long, stipules up to 3 cm long by half as wide, tendrils often more than 35 cm long, flower 11 to 12.5 cm, bracts 3 cm long, sepals 5 cm by 3 cm with short bristle, inner surface sometimes flushed pale claret purple, petals 6.2 cm by 2.5 cm, claret purple inside fading to white at edges, white flushed pale claret purple outside, filaments crimson for 2 cm at base then banded with 2 mm wide zones of purple, white, purple, white with final 2 cm mottled purple, style arms white finely spotted purple, stigma olive green, anther filaments white spotted red.

This hybrid is not widely available, and Vanderplank [2] commented that what is often labelled as P. ×caponii is probably a hybrid of P. alata. During a recent visit to the Hill House Nursery in Devon [3], I saw P. ×caponii for sale. On enquiring about the origin of this plant, I was told that a Mr Jim Jenkins had given it to the nursery ten years ago. He had once been in charge of the Temperate House at the Royal Botanic Gardens, Kew, but had long since retired. This seemed to suggest that it was a genuine example of P. ×caponii. But, although it matched the original description reasonably well, the plant and that published description were much closer in appearance to P. ×belotii (see Figure 1). Unfortunately, Beckett’s paper [1] did not include a coloured image of P. ×caponii, but an early photograph [4] shows a flower that, although looking much redder, is still similar to P. ×belotii and the closely-related P. ×allardii.

The flowers of the hybrid (P. ×decaisneana×P. racemosa) as shown in Figure 2 [5] and of P. ×cardinalis (i.e. P. alata ×P. racemosa) are dark red. It is reasonable to assume that any cross between P. quadrangularis and P. racemosa would be extremely similar [6] regardless of whether it is a diploid or a triploid. But, in Figure 2, the inner surfaces of the sepals could hardly be described as “sometimes flushed pale claret purple” nor could the inner surfaces of the petals be said to be “fading to white at edges”. Some years ago, Vanderplank produced the hybrid P. quadrangularis× P. caerulea [7], which he said was similar to P. ×caponii. This similarity was based on a comparison with the original herbarium specimen of P. ×caponii held by the Royal Horticultural Society at Wisley [8].

I therefore conclude that P. caerulea, and not P. racemosa,is more likely to have been the male parent of P. ×caponii. In other words, P. ×caponii is a triploid form of

P. ×allardii. Although Beckett [1] may well have used pollen from P. racemosa, the resulting hybrid can be explained as a result of contamination with pollen from

P. caerulea [9].

Legends to Figures

Figure 1. The hybrid P. ×belotii. Photograph by Les King

Figure 2. The hybrid (P. ×decaisneana×P. racemosa). Photograph by Johann

Kienbichl

References and Notes

[1] Beckett, K.A., A Hybrid Passion Flower, Journal of the Royal Horticultural

Society, 184 – 186 (1960)

[2] Vanderplank, J., ‘Passion Flowers’, 2nd edition, page 65, National Collection of

Passiflora, 1996

[3]

[4] Harris, C.C.,House Plants and Indoor Gardening, page 57, Octopus Books,

London, 1973

[5] The hybrid (P. ×decaisneana×P. racemosa) was raised by Johann Kienbichl.

See (29 July 2003)

[6] P. ×decaisneana is the hybrid (P. quadrangularis × P. alata)

[7] Vanderplank, J., ‘Passion Flowers’, 2nd edition, page 189, National Collection of

Passiflora, 1996

[8] Vanderplank, J., personal communication

[9] Such contamination seems to be a not-uncommon problem in hybridisation. An

exactly similar event probably gave rise to P. ‘Sapphire’. Although Vanderplank was quite certain that he had used P. quadrifaria to pollinate P. edulis f. flavicarpa, most believe that P. ‘Sapphire’ has P. caerulea as the pollen parent (see Wettges, M. Des Rätsels Lösung. Die wahre Abstammung von Passiflora ‘Sapphire’, Passiflorunde 9 (4), 8, 2001).

German translation by E. Kugler published in Passiflounde 12(1), 12-13 (2004)